[Senate Hearing 111-703]
[From the U.S. Government Publishing Office]
S. Hrg. 111-703
FLOODING IN BISMARCK/MANDAN AREAS OF NORTH DAKOTA
=======================================================================
HEARING
before a
SUBCOMMITTEE OF THE
COMMITTEE ON APPROPRIATIONS UNITED STATES SENATE
ONE HUNDRED ELEVENTH CONGRESS
FIRST SESSION
__________
SPECIAL HEARING
NOVEMBER 11, 2009--BISMARCK, ND
__________
Printed for the use of the Committee on Appropriations
Available via the World Wide Web: http://www.gpo.gov/fdsys
__________
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COMMITTEE ON APPROPRIATIONS
DANIEL K. INOUYE, Hawaii, Chairman
ROBERT C. BYRD, West Virginia THAD COCHRAN, Mississippi
PATRICK J. LEAHY, Vermont CHRISTOPHER S. BOND, Missouri
TOM HARKIN, Iowa MITCH McCONNELL, Kentucky
BARBARA A. MIKULSKI, Maryland RICHARD C. SHELBY, Alabama
HERB KOHL, Wisconsin JUDD GREGG, New Hampshire
PATTY MURRAY, Washington ROBERT F. BENNETT, Utah
BYRON L. DORGAN, North Dakota KAY BAILEY HUTCHISON, Texas
DIANNE FEINSTEIN, California SAM BROWNBACK, Kansas
RICHARD J. DURBIN, Illinois LAMAR ALEXANDER, Tennessee
TIM JOHNSON, South Dakota SUSAN COLLINS, Maine
MARY L. LANDRIEU, Louisiana GEORGE V. VOINOVICH, Ohio
JACK REED, Rhode Island LISA MURKOWSKI, Alaska
FRANK R. LAUTENBERG, New Jersey
BEN NELSON, Nebraska
MARK PRYOR, Arkansas
JON TESTER, Montana
ARLEN SPECTER, Pennsylvania
Charles J. Houy, Staff Director
Bruce Evans, Minority Staff Director
------
Subcommittee on Energy and Water Development
BYRON L. DORGAN, North Dakota, Chairman
ROBERT C. BYRD, West Virginia ROBERT F. BENNETT, Utah
PATTY MURRAY, Washington THAD COCHRAN, Mississippi
DIANNE FEINSTEIN, California MITCH McCONNELL, Kentucky
TIM JOHNSON, South Dakota CHRISTOPHER S. BOND, Missouri
MARY L. LANDRIEU, Louisiana KAY BAILEY HUTCHISON, Texas
JACK REED, Rhode Island RICHARD C. SHELBY, Alabama
FRANK R. LAUTENBERG, New Jersey LAMAR ALEXANDER, Tennessee
TOM HARKIN, Iowa GEORGE V. VOINOVICH, Ohio
JON TESTER, Montana
DANIEL K. INOUYE, Hawaii, (ex
officio)
Professional Staff
Doug Clapp
Roger Cockrell
Franz Wuerfmannsdobler
Carolyn E. Apostolou (Minority)
Tyler Owens (Minority)
Administrative Support
Molly Barackman-Eder
C O N T E N T S
----------
Page
Statement of Senator Byron L. Dorgan............................. 1
Statement of Colonel Robert J. Ruch, District Commander, Omaha
District, Corps of Engineers--Civil, Department of the Army,
Department of Defense--Civil................................... 3
Prepared Statement........................................... 6
Statement of Hon. John Warford, Mayor, Bismarck, North Dakota.... 8
Prepared Statement........................................... 10
Statement of Hon. Timothy A. Helbling, Mayor, City of Mandan,
North Dakota................................................... 11
Prepared Statement........................................... 12
Statement of Ken Royse, Chairman, Missouri River Joint Water
Resource Board................................................. 13
Prepared Statement........................................... 16
Statement of Michael Gunsch, District Engineer, Burleigh County
Water Resource District........................................ 17
U.S. Army Corps of Engineers Omaha District--Oahe-Bismarck Area
Stud-
ies............................................................ 19
Summary of the Flood Potential................................... 20
Existing Conditions.............................................. 21
Future Conditions................................................ 23
The Alternatives................................................. 27
Channel Dredging................................................. 28
Channel Cutoffs.................................................. 29
Bank Stabilization............................................... 30
Levees........................................................... 31
Garrison Operational Changes..................................... 32
Oahe Operational Changes......................................... 34
Land Acquisition................................................. 35
Flood Plain Management........................................... 35
Impacts of Siltation of the Missouri River in the State of North
Dakota Summary Report.......................................... 41
Appendix A--Identification of Sources and Deposits and Locations
of Erosion and Sedimentation................................... 57
Appendix B--Economic Impact of Sedimentation and Erosion Along
the Missouri River, North Dakota............................... 90
Appendix C--Impacts of Siltation of the Missouri River on
Recreation in North Dakota..................................... 114
Appendix D--Impact of Siltation on Hydropower Generation,
Missouri River, North Dakota................................... 128
Appendix E--Impact of Silation of the Missouri River on Fish and
Wildlife in North Dakota....................................... 179
Appendix F--Impact of Siltation on Flood Control Missouri River,
North Dakota................................................... 196
Appendix G--Impacts of Siltation of the Missouri River on Indian
and Non-Indian Historical and Cultural Sites in North Dakota... 218
Exhibit 1--Legal Sections in Files and Literature Search......... 242
Exhibit 2--Glossary of Archaeological Terms...................... 243
Exhibit 3--Environmental Compliance Requirements................. 243
Missouri River Flood Hazard Mitigation--Bismarck/Mandan Project
Summary and Risk Assessment--Deadfall Tree Removal Grant
Application.................................................... 245
Project Description.............................................. 245
Project Purpose.................................................. 246
Opinion of Probable Cost......................................... 246
Benefit--Cost Ratio Determination................................ 246
Summary Notes.................................................... 248
Acknowledgments of Data Sources.................................. 248
Appendix A--Aerial and Field Reconnaissance Photo Record......... 249
Prepared Statement of Michael Gunsch............................. 264
Appendix F--Impact of Siltation on Flood Control, Table 3.1--
Flood Elevation Comparison..................................... 265
Statement of Dale Frink, State Engineer, North Dakota State Water
Commission..................................................... 275
FLOODING IN BISMARCK/MANDAN AREAS OF NORTH DAKOTA
----------
WEDNESDAY, NOVEMBER 11, 2009
U.S. Senate,
Subcommittee on Energy and Water Development,
Committee on Appropriations,
Bismarck, ND.
The subcommittee met at 7:15 p.m., in the Bismarck City
Commission Room, Bismarck, ND, Hon. Byron L. Dorgan (chairman)
presiding.
Present: Senator Dorgan.
statement of senator byron l. dorgan
Senator Dorgan. Ladies and gentlemen, we'd like to begin
the hearing. This is a hearing of the United States Senate
Energy and Water Appropriations Subcommittee. I'm Senator Byron
Dorgan, chairman of that subcommittee.
I'm joined by Roger Cockrell, who is the professional staff
member on the water side of that subcommittee and works on the
water issues across the United States and knows more about
water than most anybody in the United States Senate.
Justin Schardin is also with me, who works on my personal
staff on water and other related issues.
I wanted to indicate as well representatives of Senator
Conrad's staff and Congressman Pomeroy's staff are with us,
Russ Keys is in the back of the room. Russ, could you stand?
And Marty Beckell is here from Senator Conrad's office.
I appreciate both of them being with us today. Obviously on
North Dakota issues I work very closely with Congressman
Pomeroy and Senator Conrad.
This is a field hearing of the Energy and Water
Subcommittee. What we will do is take testimony, and following
that testimony we will also accept in the permanent hearing
record any submissions for 2 weeks following tonight. You may
submit them to the United States Senate, care of my office or
to the Senate Energy and Water Appropriations Subcommittee.
They will be made a part of the permanent record.
I want to explain to you what we're trying to do and why
I'm here. After what happened last spring in North Dakota with
a very substantial amount of flooding many parts of our State,
we, of course, became very active on the Red River,
particularly in the Fargo/Moorhead area and other related areas
of flooding on the Red River. I'm sure it was not lost on
everybody in North Dakota that we came very close to having a
significant, significant devastation of the largest population
center as a result of a record flood. But the levees held.
Through a heroic flood fight, much less damage was done than
could have been.
So we've spent a lot of time thinking about and working on
and working with local government officials with respect to
flood control on the Red River. We have also now, as a result
of the chronic flooding that happened in Valley City and
Jamestown and in other areas on the Sheyenne and the James,
we've initiated certain studies with respect to both the
Sheyenne River system and the James River system. And with the
Corps of Engineers we are working through a reconnaissance
study on both river systems right now.
I just put the money in the appropriations bill. The
President just signed my legislation the Energy and Water
Appropriations bill just days ago. And that includes sufficient
funding for a reconnaissance study on the James River system
and the Sheyenne River system. Obviously that's because
substantial flooding events occurred in some very large cities,
especially on both river systems.
The questions today are what happened with respect to
flooding in and around Bismarck, North Dakota last spring.
What happened?
What caused it?
What were the consequences?
Was it a once in a lifetime event that was a perfect storm
or was it something that could happen again?
If so, what are the odds of it happening again?
If so, what kinds of things can be done to minimize the
chances of it happening again?
I was here, along with my colleagues during that period.
And I understood that the folks here in the Bismarck/Mandan
region spent a lot of sleepless nights trying to figure out
what on earth was happening. And how do you respond to it? Ice
jams and a whole series of things on this Missouri River that
were very significant and could have had a devastating impact
on these communities. Now it had an impact on some people's
houses and so on, but the impact was less than it could have
been had the worst fears been imagined.
So the questions for this hearing tonight are, what were
the causes of the flooding this spring?
What was done to mitigate the flooding during the event?
What can be done in the future to prevent this type of
flooding from happening again here in the Bismarck/Mandan area?
The flood control process, if in fact the conclusion of
this hearing is that there needs to be some mechanism by which
some flood control projects are developed or some means of
flood control would be achieved, is a bottom up process. By
that I mean just as in Fargo and Moorhead, the Federal
Government doesn't come in and say to them here's the kind of
project you ought to have. What happens is the local people
decide here's the kind of project that we think we need.
Then we begin a reconnaissance study then a feasibility
study to determine whether or not there is a Federal interest.
If so, do we meet the cost benefit ratio? There has to be a
number of criteria that are met.
If there is a project that is seen to benefit a region that
would reduce the prospect of flooding, it has to be three
things.
It has to be technically sound. In other words, it has to
be buildable, No. 1. It must be operable by a non-Federal
entity once it's built.
No. 2, it has to be environmentally sustainable. That means
that the environment of the impacted area is not degraded by
the construction of a project.
No. 3, it has to be economically viable. That is, for the
Federal Government to participate in any kind of a project, the
plan the Corps would recommend would have to have a minimum of
$1 of benefit for every dollar that is invested.
So all of those things are part of a discussion that we
will hear tonight, again, what happened?
What do we think caused it?
What are the consequences or what is the likelihood of it
happening again?
What kinds of things can be done to minimize the chance of
it happening again?
With that we have Colonel Ruch, the Commander of the Corps
of Engineers Omaha District, who has come up to join us.
Colonel, we appreciate your being here.
We will hear from the Honorable John Warford, the mayor of
Bismarck, North Dakota.
We will also hear from the Honorable Tim Helbling, the
mayor of Mandan.
We'll also hear from Ken Royse, the Chairman of the
Missouri River Joint Water Resources Board and Mike Gunsch, the
engineer for the Burleigh County Water Resource District.
I appreciate very much all of you being here on time and
ready to go. We will begin with you, Colonel Ruch and then
we'll go down the line. I intend to ask a series of questions.
Hopefully we can get on the record all that we need to have on
the record.
I will, depending on time, be willing to entertain some
comments from the audience following the statements and my
questions. I would do that on the basis that you would give us
your name and put your statement on the record. I would want to
do that with a minimum number if we can.
But I'm here because I want to hear all of you. We've
selected the witnesses that I think will represent the opinion
and the interest of the region.
Colonel Ruch, thank you. You may proceed. Your entire
statement, as will be the case with all witnesses, will be part
of the permanent record, so you may summarize.
STATEMENT OF COLONEL ROBERT J. RUCH, DISTRICT
COMMANDER, OMAHA DISTRICT, CORPS OF
ENGINEERS--CIVIL, DEPARTMENT OF THE ARMY,
DEPARTMENT OF DEFENSE--CIVIL
Colonel Ruch. Thank you, Senator. Chairman Dorgan, my name
is Colonel Robert J. Ruch, Commander of the Omaha District,
U.S. Army Corps of Engineers. Thank you for the opportunity to
testify today on 2009 flooding in central and south----
Senator Dorgan. Is your microphone turned on, Colonel?
Colonel Ruch. It is.
Senator Dorgan. It is? Ok. Would you pull it a little
closer?
Colonel Ruch. I wanted to show you that emergency
operations in disaster response have the utmost importance at
the Corps of Engineers. It was identified by the Chief of
Engineers as our number one campaign goal. And we stand ready
to respond on a moment's notice to contingency operations
worldwide in support of natural disasters as well as combat and
stabilizing operations.
I'd like to give you a brief run down on the conditions
leading to this year's floods.
How the Corps responded to the request for assistance.
And the summary to post flood coordination.
This year's flooding in North Dakota was a direct result of
historic snow over the winter of 2008-09. Many communities in
the central part of the State, including Bismarck, recorded
more than 100 inches of snow. Rapid melting and spring rains
resulted in widespread flooding on the Missouri River, the
Knife River, the Cannonball and Beaver Creek as well as other
streams and tributaries.
With forecasts for high tributary runoff below Garrison
Dam, the Missouri River Water Management Office in Omaha began
with close coordination with the State of North Dakota and
managers of water supply intakes, powerplants and other
interest along the river upstream from Bismarck. A substantial
ice jam in the Missouri River south of Bismarck on March 23,
2009 prompted a request for Corps technical assistance. We
deployed ice jam experts from both the Omaha District and the
Cold Regions Research and Engineering Laboratory in Hanover,
New Hampshire to advise North Dakota emergency management
officers on blasting the jam and other measures to relieve
flooding.
Concurrently another significant ice jam formed upstream
from Bismarck raising concerns that this jam could break free
and move downstream to join the other one. To alleviate the
threat, the Corps collaborated with the State to make the
unprecedented decision to cut all releases from the Garrison
Dam, while the downstream jam was blasted and allowed to break
up.
One hundred miles east of Bismarck rapid snow melt
exacerbated by spring rains resulted in projected runoff in the
James River in excess of the 1997 record pool elevation of both
Pipestem and Jamestown reservoirs. Engineers from the Corps,
the Bureau of Reclamation and the National Weather Service
analyzed mountain runoff scenarios. The forecast predicted that
both dams would see elevations which would overtop the spillway
crests resulting in unregulated releases downstream and the
potential for significant flooding.
Due to early coordination with the State, the city of
Jamestown and other communities in North Dakota officially
requested assistance from the Corps in early March. In response
we constructed advance measures in Jamestown, LaMoure and
Ludden. These measures consisted of temporary levees and flood
walls, interior drainage pumps and 24 hour surveillance and
monitoring on both of the dams.
Forecasts for combined releases from both reservoirs were
projected to exceed 4,000 cubic feet per second which was more
than double the record of 1,800 cubic feet per second set
during the 1997 event. Releases were gradually increased to a
maximum of 3,200 cubic feet per second in late April. They were
held steady at that level due to serious infiltration problems
with the city's sewer system at higher levels. Releases
remained at 3,200 for approximately a month. And then were
gradually reduced back to normal levels.
After the flood threat had passed and the reservoirs were
sufficiently drawn back down to more normal levels, all the
temporary measures were removed. Reservoir storage evacuation
was completed by late August. The event lasted 133 days.
Overall the Omaha District committed 177 personnel and
expended $7.7 million in emergency funding, $2.4 million in
FEMA debris funding, constructed 4.5 miles of temporary levees
and floodwalls in Jamestown and 4,600 feet of temporary
structures in LaMoure.
We deployed more than 1.35 million sandbags, 10 pumps, and
14,000 feet of Hesco Bastions, 3,300 feet of Rapid Deployable
Floodwall, and Portadam products as well.
These efforts prevented an estimated $70 million in
damages.
Homes and businesses in Jamestown and LaMoure were not
flooded.
As the reservoirs dropped and the James River receded,
personnel from our Garrison and Oahe projects were instrumental
in opening the lines of communications regarding Corps
authorities and programs, which could address flood risks on a
long-term basis. The Corps has an array of authorities and
programs that may assist local communities with addressing
flood risks. As a result of this year's flooding, the Omaha
District has received numerous requests from communities in
North Dakota, Jamestown, Stutsman County, Emmons County and
Mercer County. We have initiated coordination meetings with
these communities and have already conducted site visits to a
few with more scheduled in the weeks to come.
Also the State of North Dakota, FEMA, and the Corps have
been developing a charter to establish a Silver Jackets Program
for the State. The Silver Jackets Program will establish a
coordinating committee to help maintain communications and
serve as a clearinghouse for prioritizing activities among the
various agencies. I want to commend the State for taking this
initiative. I believe that the visibility that comes with this
designation will position the various projects within the State
to better compete for the limited State and Federal resources.
The Energy and Water Development Appropriations Act of 2010
includes $150,000 for the Upper James River. We will soon begin
coordination with State and local officials to decide how best
to proceed with the study.
Also on the James, the Corps allocated $127,000 from the
American Recovery and Reinvestment Act funding, which has been
used to develop a new hydrologic forecasting model for the
James River upstream from the Jamestown and Pipestem Dams and
downstream to LaMoure.
The dam safety program has received funding for detailed
topographic mapping of the shorelines of the two reservoirs and
along the entire James River floodplain from the dams
downstream to the North Dakota/South Dakota State line. The new
mapping is scheduled for acquisition this fall with final
delivery of the maps in June 2010.
In addition we continue to work with the North Dakota Task
Force on Missouri River Restoration initiatives. Under that
authority we completed an assessment report this past June to
help identify sedimentation issues and concerns along the
Missouri River. We are currently working with the Task Force to
develop a plan for moving forward with projects.
Finally on October 1, 2009 we initiated a new study to re-
examine the original authorized purposes of the Missouri River
of the Flood Control Act of 1944, also known as the Pick-Sloan
Plan. The study was authorized by section 108 of the Omnibus
Appropriations Act of 2009. It is anticipated that the cost
will be $25 million to complete.
prepared statement
The overall purpose of the study is to ``review the
original project purposes based on the Flood Control Act of
1994 . . . to determine if changes to the authorized project
purposes and existing Federal water resource infrastructure may
be warranted.'' We are currently developing a Project
Management Plan and are in the midst of collecting preliminary
stakeholder and public input on the engagement strategies in
order to develop a comprehensive, public involvement plan.
Formal scoping of the project is scheduled to commence in April
2010. This study will be a major Corps undertaking, co-led by
the Omaha and Kansas City Districts. And we plan to work with
State, local, tribal and public interests throughout its
duration.
Chairman Dorgan, I appreciate the opportunity to be here
today. And I'd be happy to answer any questions.
[The statement follows:]
Prepared Statement of Colonel Robert J. Ruch
Chairman Dorgan, my name is Colonel Robert J. Ruch, Commander of
the Omaha District, U.S. Army Corps of Engineers. Thank you for the
opportunity to testify today on the 2009 flooding in central and
southeastern North Dakota.
I want to assure you that emergency operations and disaster
response are of upmost importance to the Corps of Engineers. It was
identified by the Chief of Engineers as our No. 1 Campaign Goal, and we
stand ready to respond on a moments notice to contingency operations
worldwide in support of natural disasters as well as combat and
stabilizing operations.
I would like to give a brief rundown of the conditions leading to
this year's floods, how the Corps responded to requests for assistance,
and a summary of post flood coordination.
This year's flooding in North Dakota was a direct result of
historic snow over the winter of 2008-2009. Many communities in the
central part of the State, including Bismarck, recorded more than 100
inches of snow.
Rapid melting, exacerbated by spring rains, resulted in widespread
flooding on the Missouri River, the Knife River, Cannonball River, and
Beaver Creek as well as many other streams and tributaries. With
forecasts for high tributary runoff below Garrison Dam, the Missouri
River Water Management Office in Omaha began close coordination with
the State of North Dakota and managers of water supply intakes, power
plants, and other interests along the river upstream from Bismarck.
A substantial ice jam in the Missouri River south of Bismarck on
March 23, 2009 prompted a request for Corps technical assistance. We
deployed ice jam experts from both the Omaha District and the Cold
Regions Research and Engineering Laboratory in Hanover, New Hampshire
to advise North Dakota Emergency Management officers on blasting the
jam and other measures to relieve flooding.
Concurrently, another significant jam formed upstream from
Bismarck, raising concerns that this jam could break free and move
downstream to join the other one. To alleviate the threat, the Corps
collaborated with the State to make the unprecedented decision to cut
all releases from Garrison Dam while the downstream jam was blasted and
allowed to break up.
A hundred miles east of Bismarck, rapid snow melt, exacerbated by
spring rains, resulted in projected runoff in the James River in excess
of the 1997 record pool elevations of both Pipestem and Jamestown
Reservoirs. As engineers from the Corps, Bureau of Reclamation, and
National Weather Service analyzed melt and runoff scenarios, the
forecasts predicted that both dams could see elevations, which would
overtop their spillway crests resulting in unregulated releases
downstream and the potential for significant flooding.
Through early coordination with the State, city of Jamestown, and
other communities, North Dakota officially requested assistance from
the Corps in early March. In response, we constructed Advanced Measures
in Jamestown, LaMoure, and Ludden. These measures consisted of
temporary levees and floodwalls, interior drainage pumps, and 24-hour
surveillance and monitoring on both dams.
Forecasts for combined releases from both reservoirs were projected
to exceed 4,000 cubic feet per second (cfs), more than double the
record of 1,800 cfs set during the 1997 event. Releases were gradually
increased up to a maximum of 3,200 cfs in late April. They were held
steady at that level due to serious infiltration problems with the
city's sewer system at higher levels.
Releases remained at the 3,200 cfs level for approximately a month
and then were gradually reduced back to normal levels. After the flood
threat had passed and the reservoirs were sufficiently drawn back to
more normal levels, all the temporary measures were removed. Reservoir
storage evacuation was completed by late August.
The event lasted 133 days. Overall, Omaha District committed 177
personnel and expended $7.7 million in emergency funding, $2.4 million
in FEMA debris funding, constructed 4.5 miles of temporary levees and
floodwalls in Jamestown and 4,600 feet of temporary structures in
LaMoure. We deployed more than 1.35 million sandbags, 10 pumps, and 232
rolls of plastic sheeting, as well as 14,000 feet of Hesco Bastions,
3,300 feet of Rapid Deployable Floodwall, and 1,250 linear feet of
Portadam products. These efforts prevented an estimated $70 million in
damages.
Homes and business in Jamestown and LaMoure were not flooded.
As the reservoirs dropped and the James River receded, personnel
from our Garrison and Oahe projects were instrumental in opening the
lines of communications regarding Corps authorities and programs, which
could address flood risks on a long-term basis. The Corps has an array
of authorities and programs that may assist local communities with
addressing flood risks. As a result of this year's flooding, the Omaha
District has received numerous requests from communities in North
Dakota (Jamestown, Stutsman County, Emmons County and Mercer County).
We have initiated coordination meetings with these communities and have
already conducted site visits to a few with more scheduled in the weeks
to come.
Also the State of North Dakota, FEMA, and the Corps have been
developing a charter to establish a Silver Jackets Program for the
State. The Silver Jackets Program will establish a coordinating
committee to help maintain communications and serve as a clearinghouse
for prioritizing activities among the various agencies. I want to
commend the State for taking this initiative. I believe that the
visibility that comes with Silver Jackets designation will position the
various projects within the State to better compete for limited State
and Federal resources.
The Energy and Water Development Appropriations Act of 2010
includes $150,000 for the Upper James River. We will soon begin
coordination with State and local officials to decide how best to
proceed with the study.
Also on the James River, the Corps allocated $127,000 from the
American Recovery and Reinvestment Act funding, which has been used to
develop a new hydrologic forecasting model for the James River upstream
from the Jamestown and Pipestem Dams and downstream to LaMoure.
The dam safety program has received funding for detailed
topographic mapping of the shorelines of the two reservoirs and along
the entire James River floodplain from the dams downstream to the North
Dakota--South Dakota State line. The new mapping is scheduled for
acquisition this fall with final delivery of the maps in June 2010.
In addition, we continue to work with the North Dakota Task Force
on Missouri River Restoration initiatives. Under that authority we
completed an Assessment Report this past June to help identify
sedimentation issues and concerns along the Missouri River. We are
currently working with the Task Force to develop a plan for moving
forward with projects.
Finally, on October 1, 2009 we initiated a new study to re-examine
the original authorized purposes (Missouri River) of the Flood Control
Act of 1944 also known as the Pick-Sloan Plan. The study was authorized
by section 108 of the Omnibus Appropriations Act of 2009 and is
anticipated to cost $25 million to complete. The overall purpose of the
study is to ``review the original project purposes based on the Flood
Control Act of 1944 . . . to determine if changes to the authorized
project purposes and existing Federal water resource infrastructure may
be warranted.'' We are currently developing a Project Management Plan,
and are in the midst of collecting preliminary stakeholder and public
input on engagement strategies in order to develop a comprehensive
public involvement plan. Formal scoping of the project is scheduled to
commence in April 2010. This study will be a major Corps undertaking,
co-led by Omaha and Kansas City Districts, and we plan to work with
State, local, tribal, and public interests throughout its duration.
Chairman Dorgan, I appreciate the opportunity to be here today and
I will be happy to answer any questions you may have.
Senator Dorgan. Colonel, thank you very much.
The study of the Missouri River in section 108 is a study
that I wrote and have funded. I look forward to substantial
results from that study. I know it's going to take several
years, but at last, at long, long last we need to understand
what the management of this river should be given the realities
of the use of the river.
I would just observe that in circumstance and at times when
we've been short of water and we're moving water out of the
upstream dams in order to support one barge that's floating
downstream hauling sand and gravel. You scratch your head and
ask yourself, you know, where's the common sense here? So
that's a study that I wrote and am funding. I look forward to
have some results for the next several years.
Mayor Warford, welcome. It's good to see you. You may
proceed.
STATEMENT OF HON. JOHN WARFORD, MAYOR, BISMARCK, NORTH
DAKOTA
Mr. Warford. Thank you very much, Senator Dorgan and
members of the subcommittee, I want to thank you for allowing
me to share Bismarck's spring 2009 Missouri River flooding
experiences with you this evening.
I'm proud to tell you that Bismarck's emergency responders
performed well during our flood crisis. They used their
training and abilities to deal effectively with our emergency.
Invaluable assistance was also received throughout the flood
event from North Dakota Disaster Response and Water Management
agencies. However since the subject of this hearing is the
Federal response to the event my comments will be directed
primarily for the Federal resources utilized in dealing with
the flood.
Bismarck benefitted greatly from superb communication
between the North Dakota State Water Commission and the U.S.
Army of Corps of Engineers. This communication resulted in a
very timely decision by the Corps to hold releases from
Garrison Dam to an absolute minimum for several days to allow
ice jams in the Bismarck/Mandan area of the Missouri River to
clear. This quick response potentially saved lives and
unquestionably averted major property damage.
Bismarck and its citizens benefitted from the quick
attention of the Federal Emergency Management Agency also who
arrived as soon as the flood emergency was evident. They came
ready to help with expertise and financial resources. The
National Weather Service and the Army Corps of Engineers gave
Bismarck immediate assistance in those most difficult days when
the river and the weather were foremost in everyone's minds.
Bismarck benefitted greatly from the assistance of the
Congressional delegation of the Governor. Several times each
day phone calls were received from political leaders offering
to help. Senators Dorgan and Conrad, Congressman Pomeroy and
Governor Hoeven and yes, President Obama were available,
although the President did require the use of a cell phone. The
attention given to our citizens of our city at that time by our
political leaders was greatly appreciated and showed concern
and support during some pretty tough days.
The superb report of the North Dakota National Guard is
worthy of special recognition. Given the opportunity to utilize
Federal and State resources the National Guard was invaluable
in our flood response. The Guard's presence was visible,
accommodating and steady throughout the disaster. From sandbag
operations to evacuation to aerial recognizance to bringing in
an explosives team, the Guard provided for many pressing needs.
In the time available I cannot begin to thank everyone who
went out of their way to assist us in this most difficult time.
They helped pave the way for the recovery we have enjoyed. This
was an amazing team effort, one that I'm intensely proud of to
claim on behalf of our city.
As in the case with every crisis, part of our
responsibility is to look at what might have been done to
lessen the severity of the crisis and to prevent a
reoccurrence. This is always done in 20/20 hindsight. But it is
a necessary part of a disaster autopsy.
So the spring 2009 Missouri flood in the Bismarck area was
largely caused by ice jamming and heavy spring runoff, much of
it from the Missouri River tributaries such as the Heart and
Knife Rivers. Apple Creek, though not a factor in 2009 could
potentially impact an ice jam crisis. If the ice conditions in
the tributaries could be more closely monitored and their
impacts on the Missouri anticipated and possibly mitigated. I
think we could avoid an ice jam event of this proportion.
If the tributary contribution to Missouri were able to be
managed more completely an additional advantage would be
gained. However, if no physical event were changed. A more
thorough monitoring of tributary conditions would allow an
earlier warning of problems that could affect the Missouri.
A second recommendation of an aide might be the addition of
a Missouri River State Management Device or devices. So an ice
jam in the headwaters of the Oahe stretch of the river could
more quickly be detected. Lowland flood warnings could be given
on a more accurate and timely basis. Since ice jams are very
difficult and hard to predict additional river condition
monitoring systems may allow officials to issue earlier
warnings to residents.
Another recommendation would involve the preparation and
testing of an ice jam response plan. The city would be a very
willing contributor to the development of this plan. But it
lacks the expertise in ice jam fighting or response to rapid
river stage increases caused by flooding associated with ice
jams. The assistance of Federal and State resources would aid
greatly in this planning effort.
A fourth suggestion would involve a study of the vulnerable
areas south of Bismarck and ways in which either a temporary or
permanent dike system might aid in the prevention of flooding
from the Missouri River or Apple Creek. This study should focus
on a catastrophic ice jam on the Missouri similar to the spring
of 2009 event and consider the additive effect of a high Apple
Creek flow that might not be able to discharge into the
Missouri River.
A final recommendation recognizes that prevention of a
disaster is a proven desire of everyone who has experienced the
pain and loss caused by such an event. While this is never
entirely possible, it is reasonable to consider actions that
will eliminate the event or make it less costly. It would be
desirable to consider dredging the headwaters of the Oahe.
Chronic bank erosion and resulting siltation of the quiet
waters of the Oahe have caused many sandbars and a winding
river channel. This makes ice jamming an increasingly frequent
phenomenon.
PREPARED STATEMENT
Senator Dorgan, again, thank you once again for the
opportunity to discuss this spring 2009 flood event in the
Bismarck area. The resources you have provided to us have done
a great deal to mitigate the problem. And your willingness to
assist with further mediation of the threat is deeply
appreciated. Thank you.
[The statement follows:]
Prepared Statement of Hon. John Warford
Thank you for allowing me to share Bismarck's spring 2009 Missouri
River flood experiences with you this evening.
I am proud to tell you that Bismarck's emergency responders
performed well during our flood crisis. They used their training and
abilities to deal effectively with our emergency. Invaluable assistance
was also received throughout the flood event from North Dakota disaster
response and water management agencies. However, since the subject of
this hearing is the Federal response to this event, my comments will be
directed primarily toward the Federal resources utilized in dealing
with the flood.
Bismarck benefitted greatly from superb communication between the
North Dakota State Water Commission and the Army Corps of Engineers.
This communication resulted in a very timely decision by the Corps to
hold releases from the Garrison Dam to an absolute minimum for several
days to allow ice jams in the Bismarck-Mandan area of the Missouri
River to clear. This quick response potentially saved lives and
unquestionably averted major property damage.
Bismarck and its citizens benefitted from the quick attention of
the Federal Emergency Management Agency who arrived as soon as the
flood emergency was evident. They came ready to help with expertise and
financial resources. The National Weather Service and the Army Corps of
Engineers gave Bismarck immediate assistance in those most difficult
days when the river and the weather were foremost in everyone's minds.
Bismarck benefitted greatly from the assistance of the
congressional delegation and the Governor. Several times each day phone
calls were received from political leaders offering to help. Senators
Dorgan and Conrad, Representative Pomeroy, Governor Hoeven and yes,
President Obama, were available for press briefings, although the
President did require the use of a cell phone. The attention given to
the citizens of our city at this time by our political leaders was
greatly appreciated and showed concern and support during some pretty
tough days.
The superb support of the North Dakota National Guard is worthy of
special recognition. Given the opportunity to utilize Federal and State
resources, the National Guard was invaluable in our flood response. The
Guard's presence was visible, accommodating and steady throughout the
disaster. From sandbag operations to evacuation, to aerial
reconnaissance, to bringing in an explosives team; the Guard provided
for many pressing needs.
In the time available I cannot begin to thank everyone who went out
of their way to assist us in this most difficult time. They helped pave
the way for the recovery we have enjoyed. This was an amazing team
effort; one that I am intensely proud to claim on behalf of the city.
As is the case with every crisis, part of our responsibility is to look
at what might have been done to lessen the severity of the crisis and
to prevent a recurrence. This is always done with 20 by 20 hindsight,
but it is a necessary part of a disaster autopsy.
The spring 2009 Missouri River flood in the Bismarck area was
largely caused by ice jamming, much of it from Missouri River
tributaries such as the Heart and Knife Rivers. Apple Creek, though not
a factor in 2009, could potentially impact an ice jam crisis. If the
ice conditions in the tributaries could be more closely monitored and
their impacts on the Missouri anticipated and possibly mitigated, I
think we could avoid an ice jam event of this proportion. If the
tributary contribution to the Missouri were able to be managed more
completely, an additional advantage would be gained. However, if no
physical event were changed, a more thorough monitoring of tributary
conditions would allow an earlier warning of problems that could affect
the Missouri.
A second aid might be the addition of a Missouri River stage
measurement device or devices so an ice jam in the headwaters of the
Oahe stretch of the river could be more quickly detected. Lowland flood
warnings could be given on a more accurate and timely basis. Since ice
jams are very hard to predict, additional river condition monitoring
systems may allow officials to issue earlier warnings to residents.
Another recommendation would involve the preparation and testing of
an ice jam response plan. The city will be a very willing contributor
to the development of this plan, but it lacks expertise in ice jam
fighting or response to rapid river stage increases caused by flooding
associated with ice jams. The assistance of Federal and State resources
would aid greatly in this planning effort.
A fourth suggestion would involve a study of the vulnerable areas
of south Bismarck and ways in which either a temporary or permanent
dike system might aid in the prevention of flooding from the Missouri
River or Apple Creek. This study should focus on a catastrophic ice jam
on the Missouri, similar to the spring 2009 event, and consider the
additive effect of a high Apple Creek flow that might not be able to
discharge into the Missouri.
A final recommendation recognizes that prevention of a disaster is
the fervent desire of everyone who has experienced the pain of loss
caused by such an event. While this is never entirely possible, it is
reasonable to consider actions that will eliminate the event or make it
less costly. It would be desirable to consider dredging the headwaters
of Oahe. Chronic bank erosion and resulting siltation in the quiet
waters of Oahe have caused many sand bars and a winding river channel.
This makes ice jamming an increasingly frequent phenomenon.
Thank you once again for the opportunity to discuss the spring 2009
flood event in the Bismarck area. The resources you have provided to
help us deal with this problem and your willingness to assist with
further remediation of this threat are deeply appreciated.
Senator Dorgan. Mayor Warford, thank you. And thank you for
allowing us to use this facility here in Bismarck. I know you
spend a fair amount of time here.
The mayor of Mandan, Mr. Tim Helbling, you may proceed.
STATEMENT OF HON. TIMOTHY A. HELBLING, MAYOR, CITY OF
MANDAN, NORTH DAKOTA
Mr. Helbling. Good evening. Thank you, Senator Dorgan for
this opportunity to provide testimony on the importance of
flooding issues in the Mandan/Bismarck area. There continue to
be after effects of the spring flooding along the Missouri
River.
The city of Mandan has spent over $100,000 in the past 3
months on a temporary rock protection of our storm and sanitary
sewer outfall pipes. The cause appears to be a failure in a
rock jetty directly north of these outfall pipes. Until this
situation is rectified the river current will continue to erode
the river bank.
And we will, in turn, spend thousands more in attempts to
stabilize our infrastructure. In discussions with the Corps of
Engineers in Omaha it appears funding is very limited for this
type of project. We are asking for funding assistance as the
damage appears to be a result of a failure in the rock jetty
caused by the flooding and ice jams earlier this spring.
Flooding along the Missouri River in part was caused by
tremendous amounts of water, ice and debris flowing from the
Heart River. The Lower Heart Water Resource District feels
there are several levee areas of concern that should be
considered for structural concerns versus general maintenance
items. We have lost several feet of bank protection and
significant stretches of the river leaving the levee directly
exposed to the water current right at its toe.
Any future washouts will directly impact the levee system
in several areas. Up to this point these areas of concern have
been categorized by the Corps of Engineers as general
maintenance issues. If the vulnerable areas continue to be
considered to be general maintenance items for the Lower Heart
Water Resource District to contend with the finances of the
Lower Heart Water Resource District will not be adequate.
We have identified areas we feel are structural concerns
requiring repairs to protect the city of Mandan's
infrastructure that could total $4 to $6 million. Typically the
Lower Heart Water Resource District can reserve $15,000 to
$30,000 per year for general maintenance. At that rate, even
with a typical cost share program, a 25 percent match, our
ability to repair the structural concerns cannot realistically
be done with any reasonable time.
The value of a developed real estate in the protected areas
of Mandan can easily be considered some of the highest value
real estate in the area. The Memorial Highway, Marina Bay,
Borden Harbor, Lakewood Harbor and the entire southside of
Mandan from Highway 6 east has increased in both development
and value since the construction of the levees.
We want to recognize the assistance from the Corps of
Engineers has provided to date. As there are several projects
that are currently underway. That assistance is greatly
appreciated.
However, structural concerns should be considered for grant
programs and fast track approvals. Again, these areas of
concern have been categorized by the Corps of Engineers as
general maintenance issues. And we respectfully disagree.
PREPARED STATEMENT
I'd like to thank you for this opportunity to provide
input. And thank you for all that you have done to help the
cities of Mandan and Bismarck during the spring flooding.
[The statement follows:]
Prepared Statement of Hon. Timothy A. Helbling
Thank you for this opportunity to provide testimony on the
importance of flooding issues in the Bismarck-Mandan areas.
There continue to be the after effects of the spring flooding along
the Missouri River. The city of Mandan has spent over $100,000 in the
past 3 months on temporary rock protection of our storm and sanitary
sewer outfall pipes. The cause appears to be a failure in a rock jetty
directly north of these outfall pipes. Until this situation is
rectified the river current will continue to erode the river bank and
we in turn will spend thousands more in attempts to stabilize our
infrastructure. In discussions with the Corps of Engineers in Omaha, it
appears funding is very limited for this type of project.
We are asking for funding assistance as the damage appears to be
the result of a failure in the rock jetty caused by the flooding and
ice jams this spring.
Flooding along the Missouri River in part was caused by the
tremendous amount of water, ice and debris flowing from the Heart
River. The Lower Heart Water Resource District (LHWRD) feels there are
several levee areas of concern that should be considered for
``structural concerns'' versus general maintenance items. We have lost
several feet of bank protection in significant stretches of the river
leaving the levee directly exposed to the water current at its toe. Any
future washouts will directly impact the levee system in several areas.
Up to this point, these areas of concern have been categorized by the
Corps of Engineers as ``general maintenance'' issues.
If the vulnerable areas continue to be considered ``general
maintenance'' items for LHWRD to contend with, the finances of LHWRD
will not be adequate. We have identified areas we feel are ``structural
concerns'' requiring repairs to protect the city of Mandan's
infrastructure that could total $4 to $6 million. Typically the LHWRD
can reserve $15,000-$30,000 per year for general maintenance. At that
rate, even with the typical cost share program (25 percent match) our
ability to repair these ``structural concerns'' cannot realistically be
done in any reasonable time.
The value of the developed real estate in the protected areas of
Mandan can easily be considered some of the highest value real estate
in the area. The Memorial Highway, Marina Bay, Borden Harbor, Lakewood
Harbor and the entire south side of Mandan from Highway 6 east has
increased in both development and value since the construction of the
levees.
We want to recognize the assistance the Corps of Engineers has
provided to date, as there are several projects that are currently
underway. That assistance is greatly appreciated.
However, structural concerns should be considered for grant
programs and fast track approvals. Again, these areas of concern have
been categorized by the Corps of Engineers as ``general maintenance''
issues and we respectfully disagree.
The city of Mandan provides treated water to Missouri West Water
Systems for its rural customers and we also share our water intake
structure with Tesoro Refinery. Our intake structure rests along the
bank of the Missouri River. During the period in which water was not
being released from Garrison Dam, we kept around the clock watch to
ensure we had adequate flow into our intake. At one point we were hours
away from having no water. The Corps of Engineers and North Dakota
Department of Emergency Services worked quickly and decisively in
allowing a controlled release from Garrison Dam to ensure our intake
would continue to function.
This situation could easily present itself again, not only to the
citizens of Mandan, its rural residents, Tesoro Refinery the other
communities and power plants that rely upon water in the Missouri River
for their livelihood. Horizontal collector wells, that are now being
installed as part of the Bismarck water treatment plant, have been
explored in Mandan, however, the geology does not support this
alternative.
We believe a comprehensive review of available options should be
done if releases from Garrison Dam are significantly reduced or cut off
completely.
Thank you for the opportunity to provide input.
Senator Dorgan. Well, Mayor, thank you very much. And now
we will hear from Mr. Ken Royse, the chairman of the Missouri
River Joint Water Resource Board. Mr. Royse.
STATEMENT OF KEN ROYSE, CHAIRMAN, MISSOURI RIVER JOINT
WATER RESOURCE BOARD
Mr. Royse. Senator Dorgan, thank you for this opportunity
to provide testimony regarding the issue of flooding in the
Bismarck/Mandan area was caused or contributed to by the
Missouri River.
My name is Ken Royse. I'm a resident of Bismarck, North
Dakota. And I currently serve as chairman of the Missouri River
Joint Water Resource Board. The Missouri River Joint Water
Resource Board is a legally organized joint water board
authorized under the statute of the State of North Dakota. Our
membership are those individual county water boards which
border either Lake Sakakawea, Lake Oahe or the Missouri River.
Before I offer my testimony I would like to offer sincere
thanks to you for arranging this hearing and elevating this
issue to this level of discussion. We understand that this
hearing allows us to formally place our concerns into a
Congressional Record and provide a possible means for
improvements and changes to be implemented in the river and
reservoir management methods.
I am confident that the panel that you have assembled today
will provide you very specific discussions on the issues of
flooding which Mandan and Bismarck faced this past spring.
However my testimony to you will be in broader terms of how
several selected Federal programs are affecting the use of the
Missouri River system in our State. And how those selected
programs relate particularly to the issue of flooding in the
Bismarck/Mandan area.
The Federal programs I would like to address, each of which
have a relationship to the flooding issues we're discussing
here today, are No. 1 the work and efforts as authorized and
conducted under title VII of the Missouri River Protection and
Implementation Act of 2000.
No. 2, the Corps managed program commonly referred to as
the Emergent Sandbar Habitat Program, which is a program
implemented due to the Missouri River biological opinion for
recovery.
And No. 3, the recently passed and pending effort referred
to as a MRAPS process which is a Missouri River Authorized
Purposes Study as authorized under section 108 of the Omnibus
Appropriations Act of 2009.
The common thread of all these programs relates to the
elements of sediment siltation and bank and land erosion. All
these elements had a direct impact on the flooding which
occurred in March 2009. Relative to the title VII program as
you are aware this program has provided for a comprehensive
study to be conducted for the Missouri River system for the
State of North Dakota to identify issues and effects of
sedimentation and siltation.
The study was recently completed under the direction of the
Omaha Division of the Corps of Engineers. In this study an
attempt was made to quantify the effects siltation has had and
is having on the issues of economics, recreation, hydropower
production, fish and wildlife resources, flood control and
Indian and non-Indian historical and cultural sites. In the
section of the report under flood control the following
discussion is provided.
``Flood control issues within the Missouri River for the
Bismarck, North Dakota area are caused or affected by one, open
water seasonal flooding from Garrison Dam operations.
``Two, open water seasonal flooding from tributaries and
other residue drainage areas below Garrison Dam combining with
releases from Garrison Dam.
``Three, flooding resulting from ice jams and ice
conditions.
``And four, flooding caused by aggradation in the upper
reaches of Lake Oahe.''
And additionally it says, ``Siltation in the reach between
Garrison Dam and Lake Oahe has resulted in increased risk of
flooding in the downstream reach between the Dam and the
headwater of Lake Oahe. Because of this sediment aggradation
the impact of ice dams on seasonal flooding has increased and
is expected to increase.''
Relative to the Emergent Sandbar Habitat Program, I think
it first important to inform you that the Missouri River Joint
Board has placed itself on the record of opposing this program.
We opposed it based on the intent to the program to place or
maintain sediment deposits and sandbars within the river
system. The North Dakota Water Users and the North Dakota Water
Resource Association have also adopted similar resolutions in
opposition to this program.
While we oppose creating or enhancing sandbars for bird
habitat, we do recognize the importance of achieving ecological
balance in the river and reservoir system. Water managers and
folks that use and enjoy our river system are not anti-
environmental. We simply believe that a balance of all needs,
including a need for adequate river management for flood
protection needs to be on equal footing as fish and wildlife
and environmental needs.
Our opposition is based primarily on the damages that
siltation and sedimentation can do to the various uses of the
river.
Silt and sediment provide obvious disadvantages to the
river use in terms of excess in the channel for water and
irrigation supply and in terms of lessening the life of the
empowerment structures.
And in terms of decreasing power generation ability.
And in terms of limiting and disrupting an accessible river
system for recreation.
Sedimentation can and does contribute to flooding
conditions as we have seen this past year where a large sand
bar or sand bars acted as a restriction to the ice movement and
flow from the Heart River into the Missouri River. It was that
backed up and blocked ice which created the conditions by which
the flooding of South Bismarck and South and East Mandan
occurred.
Relative to the Missouri River authorized purposes study we
believe this effort can and should provide a means for our area
to influence a river management system which will further
secure flood protection for our area. This is an effort, as you
are aware, which is now in its infancy. The first scoping
meeting was held on this issue in early October in Pierre,
South Dakota.
At that meeting I would estimate that approximately 150
people attended. Of which, perhaps, up to one-third to one-half
were from downstream States. Even though the Corps had
conducted a scoping meeting in Kansas City supposedly for the
benefit of those users and stakeholders of the downstream
States, these downstream stakeholders apparently felt the need
to attend the Pierre, South Dakota meeting, an apparent
demonstration of the importance of this issue to them.
PREPARED STATEMENT
I think the MRAPS program allows all the States a platform
and structure to revisit a long outdated plan of management and
benefit allocation of the Missouri River system. It should be
viewed as a means where all parties upstream and downstream
interest included, can have an opportunity to have objective
discussion on the best basin wide use of that system. And it
should be a means by which the issue of the Missouri River and
reservoir system management and operations can be modified to
address flooding issues in the Bismarck/Mandan area.
Senator, thank you for holding this hearing and accepting
this testimony, if you have any questions I would be happy to
answer them.
[The statement follows:]
Prepared Statement of Ken Royse
Dear Senator Dorgan and subcommittee, thank you for this
opportunity to provide testimony regarding the issue of flooding in the
Bismarck and Mandan, North Dakota area as caused or contributed to by
the Missouri River.
My name is Ken Royse. I am a resident of Bismarck, North Dakota and
I currently serve as chairman of the Missouri River Joint Water
Resource Board. The MRJWRB is a legally organized joint water board
authorized under the statutes of the State of North Dakota; our
membership are those individual county water boards which border either
Lake Sakakawea, Lake Oahe, and/or the Missouri River.
Before I offer my testimony I would like to offer sincere thanks to
you for arranging this hearing and elevating this issue to this level
of discussion. We understand that this hearing allows us to formally
place our concerns into a Congressional Record and provides a possible
means for improvements and changes to be implemented in the river and
reservoir management methods.
I am confident that the panel you have assembled today will provide
you with a very specific discussion on the issues of flooding which
Bismarck and Mandan faced this past spring. However my testimony to you
will be in broader terms of how several selected Federal programs are
affecting the use of the Missouri River system in our State and how
those selected programs relate particularly to the issue of flooding in
the Bismarck and Mandan area.
The Federal programs I would like to address, each which have a
relationship to the flooding issues we are discussing here today, are
(1) the work and efforts as authorized and conducted under title VII of
the Missouri River Protection and Improvement Act of 2000, (2) the
Corps managed program commonly referred to as the Emergent Sandbar
Habitat Program, which is a program implemented due to the Missouri
River Biological Opinion for Recovery, and (3) the recently passed and
pending effort referred to as the MRAPS process, which is the Missouri
River Authorized Purposes Study, as authorized under section 108 of the
Omnibus Appropriations Act of 2009. The common thread of all these
programs relates to the elements of sediment, siltation, and bank and
land erosion. All these elements had a direct impact on the flooding
which occurred in March 2009.
Relative to the Title VII Program.--As you are aware this program
has provided for a comprehensive study to be conducted for the Missouri
River system of the State of North Dakota to identify issues and
effects of sedimentation and siltation. This study was recently
completed under the direction of the Omaha Division of the Corps of
Engineers. In this study an attempt was made to quantify the effects
siltation has had and is having on issues of economics, recreation,
hydropower production, fish and wildlife resources, flood control and
Indian and non-Indian historical and cultural sites. In the section of
the report under Flood Control the following discussion is provided:
``Flood control issues within the Missouri River for the Bismarck,
North Dakota area are caused or affected by (1) open-water seasonal
flooding from Garrison Dam operations, (2) open-water seasonal flooding
from tributaries, and other residual drainage areas below Garrison Dam,
combining with releases from Garrison Dam, (3) flooding, resulting from
ice jams and ice conditions, and (4) flooding.''
And additionally,
``Siltation in the reach between Garrison Dam and Lake Oahe has
resulted in increased risk of flooding in the downstream reach between
the dam and the headwater of Lake Oahe. Because of this sediment
aggradation, the impact of ice dams on seasonal flooding has increased
and is expected to increase.''
Reference Page 14, Impacts of Siltation of the Missouri River in
the State of North Dakota, Summary Report, U.S. Army Corps of
Engineers, June 2009.
Relative to the Emergent Sandbar Habitat Program.--I think it first
important to inform you that the MRJWB has placed itself on the record
of opposing this program; we oppose it based on the intent of the
program to place or maintain sediment deposits and sandbars within the
river system. The North Dakota Water Users and the North Dakota Water
Resource Association have also adopted similar resolutions in
opposition to this program.
While we oppose creating or enhancing sandbars for bird habitat, we
do recognize the importance of achieving ecological balance in the
river and reservoir system. Water managers and the folks that use and
enjoy our river system are not anti-environmental; we simply believe
that a balance of all needs, including the need for adequate river
management for flood protection needs to be on equal footing as fish
and wildlife and environmental needs.
Our opposition is based primarily on the damages that siltation and
sedimentation can do to the various uses of the river. Silt and
sediment provide obvious disadvantages to the river use in terms of
accessing the channel for water and irrigation supply, and in terms of
lessening the life of the impoundment structures, and in terms of
decreasing power generating ability and in terms of limiting and
disrupting an accessible river system for recreation. Sedimentation can
and does contribute to flooding conditions as we have seen this past
year, where a large sandbar or sandbars acted as a restriction to the
ice movement and flow from the Heart River into the Missouri River. It
was that backed up and blocked ice which created the conditions by
which the flooding of south Bismarck and south and east Mandan
occurred.
Relative to the Missouri River Authorized Purposes Study.--We
believe this effort can and should provide a means for our area to
influence a river management system which will further secure flood
protection for our area. This is an effort which, as you are aware, is
now in its infancy. The first area scoping meeting was held on this
issue in early October in Pierre, South Dakota. At that meeting I would
estimate that approximately 150 people attended, of which perhaps up to
one-third to one-half, were from downstream States. Even though the
Corps of Engineers had conducted a scoping meeting in Kansas City,
supposedly for the benefit of the users and stakeholders of the
downstream States, those downstream stakeholders apparently felt a need
to attend the Pierre, South Dakota meeting in an apparent demonstration
of the importance of this issue to them.
I think the MRAPS program allows all the States a platform and
structure to revisit a long outdated plan of management and benefit
allocation of the Missouri River system. It should be viewed as a means
where all parties, upstream and downstream interests included, can have
the opportunity to have objective discussion on the best basin wide use
of that system.
And it should be a means by which the issue of Missouri River and
Reservoir system Management and Operations can be modified to address
flooding issues in the Bismarck and Mandan areas.
Senator and subcommittee, thank you for hearing and accepting this
testimony. If you have any questions I would be happy to answer them.
Senator Dorgan. Mr. Royse, thank you very much. Let me
observe as well the meeting that was held in Pierre, South
Dakota came following a meeting that had been held in Kansas
City, Missouri. In as much as the sponsor of this study and the
person that wrote the legislation is from North Dakota, it will
be advisable at some moment for the Corps of Engineers to
decide to hold a hearing here in North Dakota. I expect that
would happen.
Let me next call on Mr. Mike Gunsch, the Houston
Engineering witness today from Bismarck, North Dakota. We
appreciate very much your being here, Mr. Gunsch. You may
proceed.
STATEMENT OF MICHAEL GUNSCH, DISTRICT ENGINEER,
BURLEIGH COUNTY WATER RESOURCE DISTRICT
Mr. Gunsch. Thank you, Senator for the opportunity to
provide testimony today regarding the flooding concerns in the
Bismarck/Mandan area. I'm currently the District Engineer for
the Burleigh County Water Resource District, also an
Engineering Consultant for the Morton County Water Resource
District. My remarks today are twofold.
One, I've got a separate set relative to the Fox Island
issue which is strictly the Burleigh County Water Resource
District.
But first I want to start with a joint statement for the
Burleigh County Water Resource Board, the Morton County Water
Resource Board and the Lower Heart Board. And it will be
primarily technical in nature. In July 2009, Houston was
retained by those three boards to take a look at the flood
issues and the alternatives associated with what's happening
with the flood issues on the Missouri River.
Senator Dorgan. Just so that I understand you. You're
employed by Houston Engineering, but testifying on behalf of
these boards?
Mr. Gunsch. Correct.
Senator Dorgan. Thank you.
Mr. Gunsch. Yes.
The cost for the effort in reviewing the alternative of the
flood mitigation issues is underwritten in part through a cost
share grant for the North Dakota State Water--or North Dakota
State Engineers, excuse me. The primary focus of that effort
that we're looking at for those boards is to define pre-
disaster mitigation alternatives that can be implemented to
reduce the existing and projected flood risks for Burleigh and
Morton County. After evaluating the March 2009 ice jam flood
event and reviewing prior studies the following objectives were
developed for further consideration.
One was a sediment debris removal from within the upper
reaches of the Oahe delta formation below the Heart River
confluence to mitigate the impacts and risks associated with
ice jam flood events and future sediment deposition.
Two, evaluate the status of potential aggradation and
ongoing changes in the stream channel conveyance downstream
from Bismarck/Mandan and its impact on the risks associated
with the ice jam and open water flood elevations.
Three is evaluate the feasibility of alternatives to lower
the current base flood elevations through Burleigh and Morton
Counties to those documented in the 1995 flood insurance study.
And there's a particular focus area. The alternatives for these
shall include, but not limited to, dredging, channel
improvements, reservoir operations, structural measures or a
combination thereof.
Four is define existing and future land uses within and
proposed bank stabilization measures along the Missouri River
correctional facility's property as necessary to achieve the
first three objectives. There is a nexus between project
construction or dredging within and along the river and the
need for access for potential use of adjacent properties for
the placement of dredged materials. So that's why that's
included.
Five is to complete an assessment to determine the
potential economic flood damages or impacts associated with
future increases in the Missouri River base flood elevations
and flood risks in Burleigh and Morton County. This effort to
include a GIS based analysis of existing and potential flood
impacts.
The tax and potential costs associated with these
objectives will include State, Federal and local issues, but
are still under development. So we do not have a number on
those at this time.
Kind of a history, concerns regarding the Oahe delta have
been around for many years. The 2009 event was just an eye
opener. I mean, it raised significant awareness that that issue
was there. There have been ice jams in the past. And there will
be ice jams in the future.
In 1985 the Corps of Engineers studied this particular
situation in a report entitled, Oahe Bismarck Area Studies,
Analysis of Missouri River Flood Potential in Bismarck, North
Dakota. They evaluated numerous alternatives in which to
mitigate the flood impacts. And we are providing a copy of that
report for the record for your use and reference.
[The information follows:]
U.S. Army Corps of Engineers Omaha District--Oahe-Bismarck Area Studies
analysis of missouri river flood potential in the bismarck, north
dakota area, august 1985
Department of the Army,
Omaha District Corps of Engineers,
Omaha, Nebraska, August 7, 1985.
To All Interested Parties: The Omaha District, Corps of Engineers
has completed its study of the residual Missouri River flood potential
at Bismarck, North Dakota, and the alternative measures for alleviating
the problem. The study conclusions were presented at a meeting of the
Coordinating Committee of the Bismarck-Mandan Missouri River
Improvement Association on May 23, 1985. Two documents--an information
paper and a more detailed technical summary--have been prepared on the
study and its conclusions.
The information paper, which is enclosed, is entitled ``Analysis of
Missouri River Flood Potential in the Bismarck, North Dakota, Area.''
Its purpose is to provide the general public with a summary of the
flood potential and an evaluation of the alternative measures for
alleviating this flood potential.
Additional copies of the information paper are available at the
Corps' Bismarck office in room 342 of the Federal Building at 3rd and
Broadway. Or, a copy will be mailed to anyone requesting it by calling
the Corps' Bismarck office at 255-4011, Extension 612.
The North Dakota State Water Commission has been furnished copies
of the technical summary and the information paper. The Commission will
be conducting a detailed technical review of this material; the review
is to be completed by November 15, 1985.
A public information meeting will be held in Bismarck after the
State Water Commission has completed its review. The purpose of the
meeting will be to answer any further questions you may have on the
study. I have invited the State Water Commission to participate in the
meeting to help answer questions. A public notice of the meeting will
be sent to those receiving this notice and to anyone who contacts the
Corps' Bismarck office and asks to be added to the current mailing
list.
Comments on the information paper may also be sent to me at the
Omaha District, Corps of Engineers, ATTN: MROPD-P, 215 N. 17th Street,
Omaha, Nebraska 68102-4910. The comment period will remain open until
December 15, 1985.
Following the Commission's review of the material, the public
information meeting, and receipt of all public comments, will consider
all views and comments and make my final recommendations.
Roger B. Whitney,
Lieutenant Colonel, Corps of Engineers, Acting District Engineer.
summary
A residual flood potential exists for the south Bismarck area along
the Missouri River upstream from the Lake Oahe project. Based on a
damage analysis of existing and projected future development, potential
flood damages could average about $900,000 per year. Also, during
future years, discharges from the upstream Garrison Reservoir will need
to be gradually reduced from the current 20,000 c.f.s. during the
winter ice-in period at Bismarck to reduce the possibility that stages
do not increase above the current target ice-in stage. This constraint
on winter hydropower generation at Garrison Dam is projected to
increase the cost of providing power to the upper Midwest region by
about $500,000 per year.
Eight alternatives for reducing the potential flood damages and
hydropower constraints were evaluated. Most were not economically
feasible; therefore, they could not be considered for implementation by
the Corps of Engineers. The Corps will, therefore, continue to reduce
releases from Garrison Reservoir at critical high discharge periods at
Bismarck--when flows from tributaries downstream from Garrison Dam
could cause flooding at Bismarck and during winter ice-in. The criteria
for ice-in, therefore, will be to continue to target ice-in at 13 feet
at the Bismarck gage. The city of Bismarck, Burleigh County, and those
developing in the flood plain should also consider additional flood
plain management measures in the form of raising new development more
than the required 1 foot above the potential existing-conditions 100-
year flood elevation and raising access roads to areas of extensive
development. These flood plain management measures would reduce future
flood damages and provide greater safety to persons living in the flood
plain. Also, those persons living or having businesses in the flood
plain should continue to take advantage of the Federal Flood Insurance
Program to minimize flood damage losses.
introduction
Since the construction of the Missouri River main stem dams,
flooding at Bismarck, North Dakota, has been limited to low-lying lands
adjacent to the Missouri River. The last major flood, the flood of
record, occurred at Bismarck in 1952--1 year before closure of Garrison
Dam, which is located 75 miles upstream. Even though the main stem
system has dramatically reduced flooding in the Bismarck area, a
residual flood potential still exists because of runoff from the
uncontrolled Missouri River drainage area between Garrison Dam and
Bismarck, the influence of sediment deposition in and upstream from
Lake Oahe, and ice affected river stages.
The Corps of Engineers has evaluated the potential for residual
flooding since 1954, when lands were first delineated for inclusion in
the downstream Lake Oahe project. At that tine, it was projected that
lands as far upstream as the Bismarck Memorial Bridge (1960 river mile
1314.2) could be influenced by the deposition of sediments in the
Missouri River channel. Development in the low-lying lands adjacent to
the river at Bismarck has increased the potential for flood damages if
a flood were to occur. Since construction of the Garrison project, the
Corps of Engineers has limited discharges from the Garrison Reservoir
during critical periods to minimize flooding of these low-lying lands
and to minimize damages to the development.
This information paper summarizes (1) the flood potential at
Bismarck before the construction of the main stem system, (2) the flood
potential as it currently exists, and (3) the projected future flood
potential. It also summarizes the technical evaluation of eight
alternatives that would reduce the flood potential, and it presents a
summary of the feasibility of these various alternatives.
summary of the flood potential
Before Construction of Main Stem Dams
Prior to the construction of the main stem dams, flood plain areas
on both sides of the Missouri River south of Bismarck were frequently
flooded to significant depths. Records dating back to 1881 indicate
that major flooding occurred on an average of once every 6 or 7 years;
however, no significant urban flood damages occurred before the 1939
flood. Because of the recurrent flooding, the south Bismarck area was
generally unsuitable for urban development. Beginning in the 1930s,
however, some people were willing to take the risk, and Bismarck
extended into the Missouri River flood plain at some points.
Fort Peck Dam in Montana was the first of six dams to be
constructed on the main stem of the Missouri River. Fort Peck Dam began
to impound water in 1937, and the project became fully operational for
flood control in 1940. Because it controlled 31 percent of the Missouri
River basin drainage area upstream from Bismarck, it reduced the
frequent flood threat at Bismarck to some degree. However, the flood
threat was not eliminated; the 1952 flood of record at Bismarck
demonstrated the continued existence of the likelihood of significant
flood events in the area. The maximum stage at the Bismarck gage (1960
river mile 1314.6) reached 27.9 feet, with an estimated discharge of
500,000 cubic feet per second (c.f.s.). Based on a gage datum of zero
equalling 1618.4 feet mean sea level (m.s.l.) (became 1618.3 feet
m.s.l. in 1979), the flood reached an elevation of 1646.3 feet m.s.l.
at the gage. The entire south Bismarck area was under up to 20 feet of
water.
Table 1 presents estimated discharges for a range of flood events--
from the 5-year up through the 500-year--at the Bismarck gage for the
period prior to the construction of Garrison Dam. Only limited gage
discharge data are available for the pre-Fort Peck Dam period;
therefore, the values presented in table 1 are based on a limited
period prior to 1953, when Garrison Dam began impounding water. As
shown in table 1, pre-system discharges approaching 1 million c.f.s.
could have occurred at Bismarck. It should also be noted that the 1952
flood of record was less than a 100-year flood event. Even though it is
a very remote flood event, the 500-year flood was included in table 1
because such events have occurred at other locations within the
Missouri River basin and the 500-year flood is commonly the basis for
the design of flood control projects in urban areas.
Table 1 also includes the estimated flood stages and the
corresponding flood elevations for the 5- through 500-year events.
These stages are based on the presystem all-seasons stage-frequency
curve for the Bismarck gage, which is a probabilistic combination of
stages for the complete range of open-water (spring, summer, and fall)
and ice-affected (winter) events.
TABLE 1.--PRESYSTEM FLOODING POTENTIAL AT THE BISMARCK GAGE
----------------------------------------------------------------------------------------------------------------
Flood
Recurrence Internal (years) Discharge Stage (feet) Elevation
(c.f.s.) (feet m.s.l.)
----------------------------------------------------------------------------------------------------------------
5............................................................... 180,000 21.6 1640.0
10.............................................................. 250,000 24.2 1642.6
25.............................................................. 360,000 26.3 1644.7
50.............................................................. 460,000 28.7 1647.1
100............................................................. 583,000 30.3 1648.7
500............................................................. 990,000 33.5 1651.9
----------------------------------------------------------------------------------------------------------------
To place the presystem flooding in perspective, potential flood
depths at the Kirkwood Shopping Center, located south of the downtown
area, were estimated. Although the parking lot varies in elevation, it
averages 1636 feet m.s.l. Floodwaters from a 10-year event would have
been about 6.5 feet deep; 50-year flood waters would have been over 11
feet deep, and 100-year flood waters would have been almost 13 feet
deep. Table 2 presents pre-system flood elevations for the 5-, 10-,
50-, and 100-year floods at five locations along the river in the
Bismarck area. These elevations are based on historical stage data for
the Bismarck gage that were obtained prior to the construction of
Garrison Dam. Based on the range of ground elevations near these
locations, flood depths of from 11 to 20 feet could have occurred along
the river with the 100-year flood. A 50-year flood would have ranged
from 9 to 17 feet in depth, and a 10-year flood would have had depths
generally from 5 to 14 feet.
TABLE 2.--POTENTIAL PRESYSTEM FLOOD ELEVATIONS IN THE BISMARCK AREA
----------------------------------------------------------------------------------------------------------------
Flood Elevations (feet m.s.l.)
Location 1960 River ---------------------------------------------------------------
Mile 5-year 10-year 50-year 100-year
----------------------------------------------------------------------------------------------------------------
Square Butte Creek.............. 1,322.5 1,645.0 1,647.3 1,651.9 1,653.5
Bismarck Gage................... 1,314.6 1,640.0 1,642.6 1,647.1 1,648.7
Heart River..................... 1,311.0 1,637.5 1,640.2 1,644.7 1,646.3
General Sibley Park............. 1,307.0 1,635.0 1,637.5 1,641.9 1,643.5
Cabe Project Boundary........... 1,303.0 1,632.5 1,634.8 1,639.4 1,641.0
----------------------------------------------------------------------------------------------------------------
existing conditions
The potential for significant flooding at Bismarck was reduced in
1953 when Missouri River flows were first controlled by Garrison Dam,
which is located about 75 river miles upstream. Estimated flood
discharges at the Bismarck gage for a range of events under existing
conditions are presented in table 3. A comparison of these discharges
with the presystem discharges shows that Garrison Dam has provided a
significant reduction in Bismarck flood discharges--a reduction of from
71 to 85 percent.
TABLE 3.--EXISTING-CONDITIONS MISSOURI RIVER DISCHARGES AT THE BISMARCK
GAGE
------------------------------------------------------------------------
Reduction in
Recurrence Interval (years) Discharge Discharge \1\
(c.f.s.) (percent)
------------------------------------------------------------------------
5....................................... 52,000 71
10...................................... 57,000 77
25...................................... 71,500 80
50...................................... 81,500 82
100..................................... 94,000 83
500..................................... 148,000 85
------------------------------------------------------------------------
\1\ As compared to the presystem discharges presented in table 1.
Even with the dramatic reduction in discharges, residual Missouri
River flooding could still be a problem at Bismarck because of
increased occupation of the 100-year flood plain. Minor lowland
flooding has occurred on a few occasions since the closure of Garrison
Dam in 1953. The greatest amount of flooding occurred in the summer of
1975, when heavy spring rains in Montana caused high discharges from
Garrison Reservoir. Although stages reached 14.2 feet at the Bismarck
gage (discharge equaled 68,900 c.f.s.), this flooding inundated only
the low-lying lands along the river. No significant economic damages
occurred in the south Bismarck area as a result of that event. A
recurrence of that flood event today could cause some damage because
many additional homes have been constructed in the area. Similar
flooding also occurred in January 1983 as the result of an ice jam in
the vicinity of the Heart River. These flood events showed that some
flooding can still occur in the south Bismarck area, although not of
the magnitude of those that occurred before construction of the main
stem system of dams.
Based on cross-sectional data obtained in 1981 and 1982, potential
flood depths have been determined for existing conditions. (The term
``existing conditions'' describes the conditions which could occur only
if the assumptions underlying the hydrologic analysis in fact occur.)
Table 4 presents the potential existing-conditions all-seasons flood
elevations for the 5-, 10-, 50-, and 100-year floods in the Bismarck
area. Flooding from major events would occur most often in the spring
and summer because of the large flows from the Knife River and Heart
River basins--the two major tributaries between Garrison Dam and Lake
Oahe. Because the effects of discharges from the Heart River are
somewhat greater than those from the Knife River and because the mouth
of the Heart River is at Bismarck, the Heart River has a greater effect
on the peak discharges and stages at Bismarck than the Knife River.
Even though the upstream half of the Heart River basin is controlled by
Heart Butte Dam, runoff from the lower, uncontrolled half of the basin
would reach Bismarck in 1\1/2\ to 2 days, the same amount of time it
takes for Garrison Reservoir releases to reach Bismarck. It, therefore,
would be impossible to cut releases from Garrison Reservoir in time to
reduce the coincident peak at Bismarck. The flood elevations presented
in table 4 represent those that would result from high flows from the
Knife River and Heart River basins coincident with Garrison Reservoir
releases. The Corps, however, will continue to reduce Garrison releases
to limit flooding at Bismarck at times of increased flood potential
because, under certain circumstances, flooding could be reduced when
the high discharges are primarily from the Knife River and some minor
tributaries upstream from Bismarck. Table 5 shows how much lower
existing-conditions stages are than those presented in table 2 for the
presystem flooding conditions. Briefly, the potential existing-
conditions flooding in the south Bismarck area would be is from about 7
feet lower for the 5-year event to about 13 feet lower for the 100-year
event.
TABLE 4.--POTENTIAL EXISTING-CONDITIONS ALL-SEASONS FLOOD ELEVATIONS IN THE BISMARCK AREA
----------------------------------------------------------------------------------------------------------------
Flood Elevations (feet m.s.l.)
Location 1960 River ---------------------------------------------------------------
Mile 5-year 10-year 50-year 100-year
----------------------------------------------------------------------------------------------------------------
Square Butte Creek.............. 1,322.5 1,637.8 1,638.0 1,638.9 1,640.0
Bismarck Gage................... 1,314.6 1,632.7 1,633.3 1,634.5 1,635.7
Heart River..................... 1,311.0 1,630.4 1,631.2 1,632.7 1,633.9
General Sibley Park............. 1,307.0 1,628.0 1,629.0 1,630.5 1,631.7
Oahe Project Boundary........... 1,303.0 1,625.6 1,626.5 1,628.0 1,629.2
----------------------------------------------------------------------------------------------------------------
TABLE 5.--REDUCTION IN POTENTIAL FLOOD ELEVATIONS FROM PRESYSTEM TO EXISTING CONDITIONS
----------------------------------------------------------------------------------------------------------------
Flood Elevation Reduction (feet)
Location 1960 River ---------------------------------------------------------------
Mile 5-year 10-year 50-year 100-year
----------------------------------------------------------------------------------------------------------------
Square Butte Creek.............. 1,322.5 7.2 9.3 13.0 13.5
Bismarck Gage................... 1,314.6 7.3 9.3 12.6 13.0
Heart River..................... 1,311.0 7.1 9.0 12.0 12.4
General Sibley Park............. 1,307.0 7.0 8.5 11.4 11.8
Oahe Project Boundary........... 1,303.0 6.9 8.3 11.4 11.8
----------------------------------------------------------------------------------------------------------------
The reduced flooding since closure of Garrison Dam in 1953
encouraged considerable residential development to take place in the
south Bismarck area--most of it occurring on the Bismarck side of the
river--even though this area has been designated as the 100-year flood
plain by the Federal Emergency Management Agency (FEMA). About 220
homes are now located in the south Bismarck area. Most of these homes--
and all of the newer homes--were constructed with their first floor
elevations at least 1 foot above the existing-conditions 100-year
flood, as required by FEMA for flood insurance purposes. They would,
therefore, be significantly affected by only the very exceptional flood
events such as the existing-conditions 100-year flood, which could
cause floodwaters about 5 feet deep in some residential areas.
The potential for economic flood damages was analyzed in December
1984. Using land use data obtained in 1980 and 1984 and the flood
depths from the existing-conditions hydraulic analysis, potential flood
damages for various flood events and, subsequently, the potential
annual damages were estimated. The estimated potential existing-
conditions flood damages in the south Bismarck area for the 5-, 10-,
100-, and 500-year events are presented in table 6. These damages are
based on damages to structures and contents; no damages were estimated
for roads, streets, utilities, lands, cleanup, or other categories.
Potential annual damages were computed based on a probabilistic
analysis. Even though the relatively infrequent events between the 100-
and 500-year events have a very low likelihood of occurring each year,
they result in about 75 percent of the existing-conditions potential
annual damages. The potential annual damages to structures and contents
for existing-conditions flooding in the south Bismarck area total about
$300,000. This is an average figure based on all damages listed in
table 6, including the 500-year event.
TABLE 6.--POTENTIAL EXISTING-CONDITIONS FLOOD DAMAGES
------------------------------------------------------------------------
Estimated
Recurrence Interval (years) Flood Damages
------------------------------------------------------------------------
5....................................................... $69,000
10...................................................... 140,000
50...................................................... 670,000
100..................................................... 1,800,000
500..................................................... 47,000,000
------------------------------------------------------------------------
Hydropower releases from Garrison Reservoir are normally reduced to
about 20,000 c.f.s. each December just prior to ice formation through
the Bismarck area. This reduction in flow is made to ensure that ice-
affected stages do not increase to the point of flooding lands adjacent
to the river at Bismarck. After the initial ice-in, discharges can be
gradually increased to an average daily discharge of about 33,000
c.f.s.; this gradual increase occurs as the streambed adjusts and the
underside of the ice becomes smoother. The short-term release reduction
limits the quantity of winter energy which can be produced. Subsequent
increased releases provide greater freedom in meeting the hydropower
needs because the Garrison powerplant can be peaked a larger part of
the day without exceeding the higher daily average release rates. The
river reaches downstream from Garrison Dam limit its full hydropower
potential; however, the Missouri River main stem system was designed
and the power is marketed in accordance with all of these conditions,
which have been maintained throughout the early life of the project.
future conditions
There are two processes occurring that will reduce the capacity of
the river in the study reach. First, as the sediment-carrying-water
moves down the Missouri River into Lake Oahe, the flow velocities
decrease and the sediment in suspension is deposited along the bottom
of the channel, thereby reducing its capacity. Second, the river is
responding to the new regulated flow regime by adjusting its sandy bed
and banks to form a generally narrower and deeper channel. This also
tends to reduce the channel capacity.
The Missouri River will continue to adjust its cross section in
response to the above two processes until a quasi-state of equilibrium
between the regulated flow regime and the river channel has been
attained. After this adjustment is completed, the channel will remain
about the same size in the Bismarck area while the delta-building
process proceeds farther into the Lake Oahe pool. Fluctuations in
channel size will occur as the flows and Lake Oahe pool levels vary
from year to year.
A baseline condition for the future operation of the Garrison
project had to be identified before the potential future-conditions
residual flooding elevations could be computed for the south Bismarck
area. The all-seasons flood elevations for the more frequent events are
closely related to the ice-in criteria. Currently, ice-in is targeted
at a 13-foot Bismarck gage stage, and this criteria will be continued.
The all-seasons flood elevations for the less frequent events are
affected by the assumed coincident Garrison releases during high
downstream tributary inflows to the Missouri River. Garrison releases
will continue to be reduced during high downstream inflow from the
tributaries whenever such action would reduce peak flows at Bismarck,
and the combined Garrison releases and tributary inflows will continue
to be the same as assumed for the existing-conditions analysis.
Table 7 presents the flood elevations that are expected to occur
once the future equilibrium condition is reached. It also presents the
increases in flood elevations over the existing-conditions flood
elevations. As shown, ultimate future flood elevations could be from
0.3 foot to 1.0 foot higher than those that currently could occur at
locations from the Bismarck gage downstream to the current Lake Oahe
project boundary.
TABLE 7.--POTENTIAL FUTURE-CONDITIONS FLOOD ELEVATIONS
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Flood Elevations (feet m.s.l.) Change from Existing conditions (feet)
Location -------------------------------------------------------------------------------------------------------------------------------
5-year 10-year 50-year 100-year 5-year 10-year 50-year 100-year
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Square Butte Creek.............................................. 1,638.0 1,638.2 1,639.4 1,640.6 +0.2 +0.2 +0.5 +0.6
Bismarck Gage................................................... 1,633.1 1,633.9 1,635.9 1,637.0 +0.4 +0.6 +1.4 +1.3
Heart River..................................................... 1,630.7 1,631.7 1,633.5 1,634.7 +0.3 +0.5 +0.8 +0.8
General Sibley Park............................................. 1,628.3 1,629.4 1,631.3 1,632.5 +0.3 +0.4 +0.8 +0.8
Oahe Project Boundary........................................... 1,626.0 1,627.0 1,629.0 1,630.1 +0.4 +0.5 +1.0 +0.9
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Table 8 shows the differences between the presystem flood
elevations for various events and the potential future-conditions flood
elevations. Significant reductions in stages from those that could have
occurred before the main stem dams were constructed have occurred and
will continue to occur in the future. The potential 5-year flood
elevations would be about 6 to 7 feet lower and the potential 100-year
flood elevations would be about 11 to 13 feet lower than they could
have been without the construction of the main stem dams.
TABLE 8.--REDUCTION IN POTENTIAL FLOOD ELEVATIONS FROM PRESYSTEM TO FUTURE CONDITIONS
----------------------------------------------------------------------------------------------------------------
Flood Elevation Reductions (feet)
Location ---------------------------------------------------------------
5-year 10-year 50-year 100-year
----------------------------------------------------------------------------------------------------------------
Square Butte Creek.............................. 7.0 9.1 12.5 12.9
Bismarck Gage................................... 6.9 8.7 11.2 11.7
Heart River..................................... 6.8 8.5 11.2 11.6
General Sibley Park............................. 6.7 8.1 10.6 11.0
Oahe Project Boundary........................... 6.5 7.8 10.4 10.9
----------------------------------------------------------------------------------------------------------------
Plate 1 shows the 5-year flood outlines for presystem, existing,
and future conditions. Plates 2 and 3 show the same comparison for the
10- and 100-year flood events, respectively.
The flooded areas shown on these plates were developed by
determining the flood elevation from the water surface profiles for a
given area and then locating the limit of flooding in that area through
the use of 2-foot contour interval topographic mapping. The flood
outlines were then transferred from the topographic mapping onto aerial
photographs; the blue shaded area represents the potential existing-
conditions flooded areas. Since most of the homes in the south Bismarck
area are built on mounds of earth which are elevated above the 100-year
flood elevation, these homes may only be surrounded by water during a
major flood event, with little or no damage resulting to the structure
itself. (The means of access to many of these, however, could be
flooded.) Because of the small scale of the aerial photography, it was
impossible to show the area flooded around each individual residence.
Therefore, the flooded areas represent only the outside limit of the
flooded area, and they do not include small islands within the flooded
area.
Flood elevations shown on a water surface profile under open-water
conditions normally apply laterally over most of the flood plain width.
However, ice along the banks of the river will generally act as a
barrier to floodwater entering some of the overbank areas under ice-
affected conditions. Thus, the flooded area corresponding to a given
ice-affected water surface elevation may not extend landward as far as
for open-flow conditions. The extent of the area flooded for a given
ice-affected stage depends to a great extent on how the river ices in.
As the river ices in and the head of the ice moves through the Bismarck
area, the river stages will normally shift upward because of the
additional roughness of the ice cover. After the initial ice-in period,
the release from Garrison Reservoir can be gradually increased. Because
of the smoothing of the streambed and the underside of the ice cover,
this increase in discharge can normally be made without a corresponding
increase in stage in the Bismarck area. Field observations made during
past ice-in periods indicate that if the river ices in as described
above, then the ice which forms along the riverbanks will act as a
barrier to floodwater entering scene overbank areas. However, it is
possible for a small ice jam to occur during the ice-in process, and
this would result in an increase in stage. If this happens, the
floodwater would flow into the overbank areas in much the same manner
as it would for open-flow conditions. The flood of January 1983 is an
example of this type of flood event. This event was the result of an
ice jam downstream from the Heart River that caused the inundation of
much of the lower portion of Fox Island. For the purposes of this
study, therefore, the flooded areas were drawn with the intent of
showing the maximum area that could be affected for a given flood
event. The flooded areas for the 5- and 10-year events were drawn by
extending the channel water surface elevation laterally across the
flood plain. However, it is recognized that, for ice-affected flood
events, this assumption may not apply.
A review of table 8 and plates 1 through 3 demonstrates that the
main stem dams will continue to significantly reduce the amount of
flooding from that which could have occurred without the construction
of the rain stem dams. As aggradation continues in the future, flood
stages would be expected to gradually increase above the existing-
conditions stages; flood damages may also increase. Additional
development is expected to occur in the south Bismarck area. This
development would also result in an increase in damages for most storm
frequencies and in an increase in potential annual damages. The
potential future-conditions flood damages presented in table 9 are
based on continued development of the south Bismarck area over the next
50 years. (Population projections were used as a basis for the rate of
development.) The potential annual damages would also increase over the
next 100 years. Two additional assumptions were made in order to
compute the flood damages. The future-conditions channel size was
assumed to occur in 20 years, and the potential annual damages were
discounted over the next 100 years. The potential annual flood damages
were estimated to increase from $300,000 under existing conditions to a
long-term average of $910,000.
TABLE 9.--POTENTIAL FUTURE-CONDITIONS FLOOD DAMAGES
------------------------------------------------------------------------
Estimated
Recurrence Interval Flood Damages
------------------------------------------------------------------------
5-Year.................................................. $93,000
10-year................................................. 310,000
50-year................................................. 2,700,000
100-year................................................ 12,200,000
500-year................................................ 129,000,000
------------------------------------------------------------------------
Although current contractual hydropower agreements will continue to
be met when future discharges are reduced during the winter months,
there will be an increase in the regional power system cost. Some of
the power that would have been generated with the more economical
hydropower units at the dam sites has to be generated by utilities
using more costly generating facilities, such as coal- or oil-fired
units. The value of this constraint in terms of increased operating
costs to the region's utilities is estimated to be about $500,000 per
year. This value is in terms of 1985 dollars, and it was determined by
discounting the increased costs over the next 100 years at an 8.375
percent discount rate. The hydropower constraint was assumed to
increase from zero currently to the full value by the year 2005 (20
years). There may also be a cost in terms of reduced reliability of the
main stem hydropower generating capabilities; however, the value of
this cost cannot be readily determined.
Table 10 presents an economic summary of the residual flood problem
at Bismarck, based on a continuation of the ice-in at a 13-foot stage.
Combined potential annual flood damages and increased power costs total
$1,410,000 per year. The magnitude of this annual cost warrants a
formulation and evaluation of alternative solutions to reduce the
impacts of the residual flood problem at Bismarck.
TABLE 10.--ECONOMIC SUMMARY OF THE POTENTIAL RESIDUAL FLOOD PROBLEM
------------------------------------------------------------------------------------------------------------------------------------------------
Potential Annual Flood Damages:
Existing Conditions................................. $300,000
Future Conditions (2085)............................ 1,370,000
Composite Annual Value.............................. 910,000Reduced Hydropower Capacity:
Average Annual Value................................ 500,000
---------------
Total............................................. 1,410,000
------------------------------------------------------------------------
the alternatives
Eight basic alternatives to the continuation of the current 13-foot
ice-in stage criteria--the baseline condition--have been evaluated as
measures to reduce the potential residual flood problem in the south
Bismarck area and to ensure the continuation of the current level of
Garrison hydropower generation in the future. These alternatives
include (1) channel dredging, (2) channel cutoffs, (3) bank
stabilization, (4) levees, (5) Garrison operational changes, (6) Oahe
operational changes, (7) land acquisition, and (8) flood plain
management. All of these alternatives do not provide a complete
solution to the flood potential and the continuation of the current
level of Garrison hydropower generation. These alternatives were
selected jointly by the Corps of Engineers and the Bismarck-Mandan
Missouri River Improvement Association--a local coordinating
committee--primarily because each alternative had possibilities for
reducing the residual flooding potential at Bismarck. A detailed
evaluation of the alternatives determined that several of them had very
limited effectiveness in reducing the residual potential for further
floods, the future hydropower constraint, or both.
The economic evaluation of the alternatives was based on a 100-year
project life at a discount rate of 8.375 percent. All costs and
benefits are in terms of 1985 dollars. As with the computation of flood
damages and increased power needs, the existing conditions were assumed
to occur in 1985 and the future conditions would first occur in the
year 2005.
A brief discussion of each of the alternatives follows. Each
discussion includes a description of the alternative, its effectiveness
in addressing the problems, and the costs, benefits, and feasibility of
the alternative.
channel dredging
Dredging the Missouri River between river miles 1315 and 1299--
refer to plate 4--was evaluated because it would provide a larger
channel through the south Bismarck area. Options 1 and 2 were designed
to convey the 5- and 10-year all-seasons flood events, respectively,
past the Bismarck gage at a 12-foot stage. The channel would be
redredged when the stages for these events would exceed 14 feet.
Options 3 and 4 are similar; however, redredging would be conducted
when stages for the 5- and 10-year events reach 13 feet. Implementation
of options 1 or 3 would initially reduce existing-conditions stages
about 2.4 feet, and implementation of options 2 or 4 would initially
reduce the existing-conditions stages 3.0 feet.
All four options would require frequent redredging to regain the
design channel capacity. Disposal areas ranging from 220 to 660 acres,
for disposal at a 10-foot depth, would be required each time redredging
is necessary. Table 11 presents information on each of the four
dredging options.
TABLE 11.--PERTINENT DATA--DREDGING
----------------------------------------------------------------------------------------------------------------
Options
Item ---------------------------------------------------------------
1 2 3 4
----------------------------------------------------------------------------------------------------------------
Design Flood.................................... 5-year 10-year 5-year 10-year
Stage Before Dredging (feet) \1\................ 14.4 15.0 14.4 15.0
Stage after Dredging (feet) \1\................. 12.0 12.0 12.0 12.0
Maximum Stage Reduction for the 5-year event \2\ 2.4 3.0 2.4 3.0
Stage Before Redredging (feet) \1\ \3\.......... 14.4 14.2 13.0 13.0
Minimum Stage Reduction for the 5-year event \2\ .............. 0.8 1.4 2.0
Redredging Frequency (years).................... 5 3 1.5 1
Disposal Areas (acres):\4\
Initial..................................... 1,250 1,400 1,250 1,400
Redredging.................................. 660 530 260 220
Total \5\................................... 14,500 18,900 18,400 23,400
----------------------------------------------------------------------------------------------------------------
\1\ All-seasons flood stage at Bismarck gage.
\2\ As compared to the existing-conditions 5-year, all-seasons flood stage.
\3\ Expected river stage for the design flood before redredging.
\4\ Disposal area estimates based on 10-foot disposal depth.
\5\ Total disposal area for 100-year period of analysis.
As shown in table 11, a sizeable area would be needed for disposal
areas. The disposal of the dredged material would affect more land than
would be flooded by a relatively large flood, and it would have
significant adverse environmental impacts.
Initially, as shown in table 11, the 5- or 10-year flood stages
would be reduced by 2.4 or 3.0 feet, respectively, for the four options
that were evaluated. However, the channel would fill in following each
dredging; this would require frequent redredging to restore the dredged
channel to its design capacity. The highest stages prior to each
redredging would be equal to or lower than the existing-conditions
flood elevations (refer to table 11--minimum stage reduction for the 5-
year event).
The costs for the four dredging options, including land acquisition
costs, are presented in table 12. The initial dredging costs exceed $30
million for all four options, while the redredging costs range from
$5.8 million to $17.2 million. Based on the varying redredging
intervals presented in table 11, the average annual costs range from
$6.1 million to $8.6 million.
TABLE 12.--ECONOMIC SUMMARY--DREDGING
----------------------------------------------------------------------------------------------------------------
Dredging Options
Item ---------------------------------------------------------------
1 2 3 4
----------------------------------------------------------------------------------------------------------------
Costs:
Initial..................................... $32,100,000 $32,900,000 $32,100,000 $32,900,000
Redredging.................................. $17,200,000 $13,400,000 $6,700,000 $5,800,000
Average Annual.............................. $6,100,000 $7,200,000 $7,200,000 $8,600,000
Average Annual Benefits:
Flood Damage Reduction...................... $670,000 $800,000 $800,000 $860,000
Hydropower.................................. $500,000 $500,000 $500,000 $500,000
Fill Reduction.............................. $40,000 $70,000 $70,000 $80,000
---------------------------------------------------------------
Total..................................... $1,210,000 $1,370,000 $1,370,000 $1,440,000
===============================================================
Net Benefits.................................... -$4,890,000 -$5,830,000 -$5,830,000 -$7,160,000
Benefit-Cost Ratio.............................. 0.2 0.2 0.2 0.2
----------------------------------------------------------------------------------------------------------------
The flood damage reduction and hydropower benefits for dredging the
channel are included in table 12. Dredging would result in a channel
that is as large or larger than the existing channel--depending on the
option and the length of time between dredgings--and always larger than
the projected future-conditions channel. The expected reduction in
potential annual flood damages would be from $670,000 to $860,000 per
year. This alternative would reduce the 100-year flood elevations by up
to 3 feet. The requirement for fill material to elevate structures in
the 100-year flood would be reduced, thereby reducing building costs by
up to $80,000 per year. The larger channel would result in no future
hydropower constraints; therefore, average annual hydropower benefits
of $500,000 would be expected with all four dredging options. The total
benefits for the dredging alternatives, therefore, range from
$1,210,000 to $1,440,000 per year.
Based on the annual costs and benefits. presented in table 12, the
benefit-cost ratio for each of the dredging options is 0.2.
channel cutoffs
Channel cutoffs, like channel dredging, would reduce flood stages
by providing better conveyance of floodflows through the south Bismarck
area. Two potential cutoff sites, one located within (upper) and the
other downstream (lower) from the south Bismarck area, are shown on
plate 5. Three options were initially considered. Only two of these
options were effective in reducing stages--option 1, the upper cutoff,
and option 2, both cutoffs; the lower cutoff, option 3, alone would not
be effective. Therefore, only options 1 and 2 were evaluated.
Both cutoffs would require extensive modifications. The upper
cutoff would require the excavation of 9,200,000 cubic yards and the
lower cutoff would require the excavation of 10,300,000 cubic yards.
The cutoff channels would be riprapped to protect against erosion, and
channel blocks would be required across the existing channel at the
upstream ends of the cutoffs. Each cutoff would require about 600 acres
for disposal of excavated material to a depth of 10 feet. The upper
cutoff would eliminate access to the remainder of Sibley Island.
Option 2 would be more effective than option 1. At Fox Island,
option 2 would initially reduce stages by 2.0 feet for the 5- and the
10-year floods; option 1 would initially reduce those stages by 1.5
feet. Over the next 15 to 20 years, both options would lose much of
their effectiveness. After 15 to 20 years, the upper cutoff would
result in a net increase above the baseline-conditions stages of 0.1
foot for the future-conditions 5-year event and a net decrease of 0.1
foot for the 10-year event. Both cutoffs would result in a net decrease
from the baseline conditions stages of 0.7 and 0.9 foot for the 5- and
10-year future-conditions events, respectively. With option 1, the
future-conditions flood stages at Fox Island, therefore, would be 0.4
foot above the existing-conditions stages. Future-conditions flood
stages would be 0.4 foot below the existing-conditions stages with
option 2.
Table 13 presents an economic summary of the channel cutoff
options. The first cost of option 1 would be $24.1 million, including
$600,000 for acquisition of the cutoff and disposal areas. Option 2
would have a first cost of $48.7 million, which also includes $600,000
for land acquisition. The lower cutoff area is on existing Lake Oahe
project lands; acquisition of additional lands would not be required.
These costs do not include land acquisition for the remainder of Sibley
Island, which would be inaccessible. The estimated annual costs to
maintain the cutoffs is about 1 percent of the first costs of
construction, or about $240,000 and $480,000 for options 1 and 2,
respectively. The estimated average annual costs of options 1 and 2 are
$2,300,000 and $4,600,000, respectively.
TABLE 13.--ECONOMIC SUMMARY--CHANNEL CUTOFFS
------------------------------------------------------------------------
Cutoff Options
Item -------------------------------
1 2
------------------------------------------------------------------------
Costs:
Construction........................ $24,100,000 $48,700,000
Operation and Maintenance........... $240,000 $480,000
Average Annual...................... $2,300,000 $4,600,000
Average Annual Benefits:
Flood Damage Reduction.............. $400,000 $580,000
Hydropower.......................... .............. $500,000
Fill Reduction...................... .............. ..............
-------------------------------
Total............................. $400,000 $1,080,000
===============================
Net Benefits............................ -$1,900,000 -$3,520,000]
Figure 3-1.--Watershed Delineation, Weather Station Locations, and USGS
Stations
TABLE 3-2.--INVENTORY OF THE ACQUIRED VARIOUS DATA AND SOURCE
------------------------------------------------------------------------
Type Description Source(S)
------------------------------------------------------------------------
Physiographic data............ Watershed boundary (8- USGS, NRCS
digit and 10-digit
HUCs).
Land use/land cover... NLCD 2001
Soil data (STATSGO/ NRCS
SSURGO).
Topographic data...... 30m DEM (NED)
Slopes................ Berger (Based on
DEM)
Stream network and NHD
water bodies.
River Mile Marker..... USACE
Flow data............. USGS
Stage Height.......... USGS
Bluff to bluff........ Berger (Based on
DEM)
Areas of Aggradations. Berger (From
USACE and USGS
Reports)
Weather data.................. Weather Station NCDC
Location.
Precipitation......... NCDC
Temperature........... NCDC
Flow data..................... Daily flow from USGS USGS
gaging stations in
North Dakota.
Administrative Boundaries..... Federal Lands (FWS, ESRI, Agency
USACE, BLM, NPS, BIA). Sources
County/State US Census
Boundaries.
Tribal Lands.......... US Census
Municipal Areas....... USACE
Recreation.................... State Park and North Dakota
Recreational Areas.
Boat Ramps............ USACE
Mitigation/Recovery USACE
Site.
Cultural...................... Lewis and Clark USACE
Campsites.
Cemetery Sites........ USACE
Transportation................ Major Highways........ US Census
Railroad.............. USACE
Soil Loss Data................ 1997 site-specific NRCS
revised soil loss
data.
Water Quality Data............ Total Suspended Solids USGS
Measurements.
------------------------------------------------------------------------
BLM--Bureau of Land Management
BIA--Bureau of Indian Affairs
DEM--Digital Elevation Model
FWS--Fish and Wildlife Service
NCDC--National Climatic Data Center
NHD--National Hydrography Dataset
NPS--National Park Service
NRCS--Natural Resources Conservation Service
USACE--United States Army Corps of Engineers
USGS--United States Geologic Survey
3.3 Land Use Distribution
Sediment can be delivered to the river from point sources located
in the watershed and it can be carried in the form of non-point source
runoff from non-vegetated or protected land areas. In addition,
sediment can be generated in the river through the processes of scour
and deposition, which are primarily a function of river flow. During
periods of high flow, erosion of the river channel occurs. The eroded
materials are deposited downstream in areas where the bed material load
exceeds the transport capacity. As a result, sources of sediment are
mainly related to the type of land use within the watershed. As such,
Berger focused on collecting the most recent information on land use
for the study area as described below.
The land use characterization for the study area of the Missouri
River was based on land cover data from the 2001 National Land Cover
Data (NLCD). Figure 3-2 displays a map of the land uses of watersheds
draining into the Missouri River within North Dakota. The drainage area
of the study area represents the entire Yellowstone River watershed and
17 HUC-8 sub-watersheds.
Table 3-3 presents the Yellowstone River and the 17 HUC-8 sub-
watersheds, as shown in Figure 3-2, with their two predominant land
uses. A detailed break-down of land uses for each watershed is
presented in Exhibit A.
TABLE 3-3.--WATERSHEDS LOCATED IN THE STUDY AREA
------------------------------------------------------------------------
Predominant Land Use
-----------------------------
Watershed HUC-8 \1\ Fraction
Category (percent)
------------------------------------------------------------------------
Yellowstone River.............. ( \2\ ) Shrub............ 41.2
Grassland/ 31.5
Herbaceous.
Lake Sakakawea................. 10110101 Cultivated Crops. 41.4
Grassland/ 37.5
Herbaceous.
Little Muddy River............. 10110102 Cultivated Crops. 68.4
Grassland/ 21.9
Herbaceous.
Upper Little Missouri River.... 10110201 Grassland/ 57.8
Herbaceous.
Shrub............ 32.0
Boxelder Creek................. 10110202 Grassland/ 64.2
Herbaceous.
Shrub............ 26.8
Middle Little Missouri River... 10110203 Grassland/ 62.9
Herbaceous.
Cultivated Crops. 14.5
Beaver Creek................... 10110204 Grassland/ 49.9
Herbaceous.
Cultivated Crops. 31.6
Lower Little Missouri River.... 10110205 Grassland/ 55.7
Herbaceous.
Deciduous Forest. 12.5
Painted Woods-Square Butte..... 10130101 Grassland/ 41.7
Herbaceous.
Cultivated Crops. 31.9
Upper Lake Oahe................ 10130102 Grassland/ 66.3
Herbaceous.
Cultivated Crops. 16.7
Apple Creek.................... 10130103 Grassland/ 56.9
Herbaceous.
Cultivated Crops. 19.3
Beaver Creek Oahe.............. 10130104 Grassland/ 57.2
Herbaceous.
Cultivated Crops. 24.2
Knife River.................... 10130201 Grassland/ 57.3
Herbaceous.
Cultivated Crops. 28.0
Upper Heart.................... 10130202 Cultivated Crops. 42.6
Grassland/ 40.1
Herbaceous.
Lower Heart River.............. 10130203 Grassland/ 51.3
Herbaceous.
Cultivated Crops. 33.5
Upper Cannonball River......... 10130204 Cultivated Crops. 48.2
Grassland/ 32.9
Herbaceous.
Cedar Creek.................... 10130205 Grassland/ 42.5
Herbaceous.
Cultivated Crops. 38.1
Lower Cannonball River......... 10130206 Grassland/ 77.0
Herbaceous.
Cultivated Crops. 15.3
------------------------------------------------------------------------
\1\ HUC-8 = Hydraulic Unit Code describing the drainage area at sub-
basin level.
\2\ This includes the entire Yellowstone River watershed.
The overall distribution of land uses in the study area by land
area and percentage is presented in Table 3-3 and a brief description
of land use classifications are presented in Table 3-4. Overall,
grassland represents the dominant land use type (43.1 percent) followed
by shrub and agriculture (both 21 percent). Cultivated crops showed
greatest fraction in agriculture lands (16.6 percent). Forested land
comprises 8.3 percent of the land cover in the study area. The smallest
percentage of land cover is for perennial ice/snow that is only part of
the land use distribution in the Yellowstone River (0.04 percent).
TABLE 3-4.--LAND USE CATEGORY AND DISTRIBUTION WITHIN THE STUDY AREA
----------------------------------------------------------------------------------------------------------------
Fraction of
Watershed's
Land Use Category NLCD Land Use Type Hectare Land Use Area
(percent)
----------------------------------------------------------------------------------------------------------------
Water/Wetland................................. Open Water...................... 423,736 2.20
Woody Wetlands.................. 189,262 0.98
Emergent Herbaceous Wetlands.... 205,991 1.07
-------------------------------
Subtotal................................ ................................ 818,989 4.25
===============================
Developed..................................... Developed, Low Intensity........ 47,078 0.24
Developed, Medium Intensity..... 7,105 0.04
Developed, High Intensity....... 1,275 0.01
-------------------------------
Subtotal................................ ................................ 55,457 0.29
===============================
Agriculture................................... Pasture/Hay..................... 740,443 3.84
Cultivated Crops................ 3,203,883 16.62
-------------------------------
Subtotal................................ ................................ 3,944,326 20.46
===============================
Grassland (Prairie)........................... Grassland/Herbaceous............ 8,301,537 43.07
===============================
Forest........................................ Deciduous Forest................ 177,801 0.92
Evergreen Forest................ 1,412,006 7.33
Mixed Forest.................... 17,412 0.09
-------------------------------
Subtotal................................ ................................ 1,607,220 8.34
===============================
Shrub......................................... Shrub........................... 4,044,607 20.98
===============================
Other......................................... Developed, Open Space........... 316,051 1.64
Barren Land (Rock/Sand/Clay).... 178,444 0.93
Perennial Ice/Snow.............. 8,417 0.04
-------------------------------
Subtotal................................ ................................ 502,911 2.61
===============================
Total................................... ................................ 19,275,047 100.00
----------------------------------------------------------------------------------------------------------------
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 3-2.--Land Use Distribution of the Study Area in the Missouri
River (ND)
TABLE 3-5.--DESCRIPTIONS OF 2001 NLCD LAND USE TYPES
------------------------------------------------------------------------
Land Use Type Description
------------------------------------------------------------------------
Open Water.............................. All areas of open water,
generally with less than 25
percent cover of vegetation
or soil.
Woody Wetlands.......................... Areas where forest or shrub
land vegetation accounts for
greater than 20 percent of
vegetative cover and the soil
or substrate is periodically
saturated with or covered
with water.
Emergent Herbaceous Wetlands............ Areas where perennial
herbaceous vegetation
accounts for 75-100 percent
of the cover and the soil or
substrate is periodically
saturated with or covered
with water.
Developed, Open Space................... Includes areas with a mixture
of some constructed
materials, but mostly
vegetation in the form of
lawn grasses. Impervious
surfaces account for less
than 20 percent of total
cover. These areas most
commonly include large-lot
single-family housing units,
parks, golf courses, and
vegetation planted in
developed settings for
recreation, erosion control,
or aesthetic purposes.
Developed, Low Intensity................ Includes areas with a mixture
of constructed materials and
vegetation. Impervious
surfaces account for 20-49
percent of total cover. These
areas most commonly include
single-family housing units.
Developed, Medium Intensity............. Includes areas with a mixture
of constructed materials and
vegetation. Impervious
surfaces account for 50-79
percent of the total cover.
These areas most commonly
include single-family housing
units.
Developed, High Intensity............... Includes highly developed
areas where people reside or
work in high numbers.
Examples include apartment
complexes, row houses and
commercial/industrial. Total
cover is 80-100 percent
impervious surfaces.
Pasture/Hay............................. Areas of grasses, legumes, or
grass-legume mixtures planted
for livestock grazing or the
production of seed or hay
crops, typically on a
perennial cycle. Pasture/hay
vegetation accounts for
greater than 20 percent of
total vegetation.
Cultivated Crops........................ Areas used for the production
of annual crops, such as
corn, soybeans, vegetables,
tobacco, and cotton, and also
perennial woody crops such as
orchards and vineyards. Crop
vegetation accounts for
greater than 20 percent of
total vegetation. This class
also includes all land being
actively tilled.
Grassland............................... Areas dominated by upland
grasses and forbs. In rare
cases, herbaceous cover is
less than 25 percent, but
exceeds the combined cover of
the woody species present.
These areas are not subject
to intensive management, but
they are often utilized for
grazing.
Deciduous Forest........................ Areas dominated by trees
generally greater than 5
meters tall, and greater than
20 percent of total
vegetation cover. More than
75 percent of the tree
species shed foliage
simultaneously in response to
seasonal change.
Evergreen Forest........................ Areas dominated by trees
generally greater than 5
meters tall, and greater than
20 percent of total
vegetation cover. More than
75 percent of the tree
species maintain their leaves
all year. Canopy is never
without green foliage.
Mixed Forest............................ Areas dominated by trees
generally greater than 5
meters tall, and greater than
20 percent of total
vegetation cover. Neither
deciduous nor evergreen
species are greater than 75
percent of total tree cover.
Shrub................................... Areas characterized by natural
or semi-natural woody
vegetation with aerial stems,
generally less than 6 meters
tall, with individuals or
clumps not touching to
interlocking. Both evergreen
and deciduous species of true
shrubs, young trees, and
trees or shrubs that are
small or stunted because of
environmental conditions are
included.
Barren Land............................. Barren areas of bedrock,
desert pavement, scarps,
talus, slides, volcanic
material, glacial debris,
sand dunes, strip mines,
gravel pits and other
accumulations of earthen
material. Generally,
vegetation accounts for less
than 15 percent of total
cover.
------------------------------------------------------------------------
Source.--National Land Cover Data (NLCD) (http://www.epa.gov/mrlc/
definitions.html).
3.4 Flow and Sediment Data
Environmental monitoring efforts in the study area include flow and
total suspended solid (TSS) measurements at three monitoring stations
on the mainstem of the Missouri River and six monitoring stations at
tributaries flowing into the Missouri River. Additionally, monitoring
stations located at the Montana/North Dakota border (USGS 06185500) and
the Yellowstone River in Montana (USGS 06329500) were included as
boundary stations. Monitoring efforts presented in this section were
conducted by the USGS.
Figure 3-1 shows the location of the USGS stations. Table 3-6
presents an inventory of available flow and TSS data at USGS monitoring
stations in the study area including the data range, number of samples,
minimum, maximum, standard deviation, and average of the data type at
each USGS station. Overall, historic and recent flow measurements were
available for the majority of the stations. On average, the Yellowstone
River delivered the largest amount of flow to the Missouri River within
North Dakota followed closely by the amount of flow delivered from
Montana. The remaining major tributaries discharging into the Missouri
River within North Dakota had a relatively small impact on the flow
budget in the Missouri River. As for TSS measurements, data were
limited and no current measurements have been taken. Nonetheless, for
comparison reason, the available TSS concentrations were graphed with
the corresponding flow in Figures A-1 through A-7 of Exhibit A. In
general, spikes of TSS levels were a direct response to high flow
events.
TABLE 3-6.--INVENTORY OF FLOW (m3/sec) AND TOTAL SUSPENDED SOLIDS (mg/L) MONITORING STATIONS IN THE STUDY AREA
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
USGS
Station River/Station Name Data Type Data Range \1\ Number of Min Max Mean STDEV
Number Samples
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ Missouri River 6185500 Missouri River near Culbertson, MT Flow............. 07/01/1941-12/31/1951 04/01/1958-present............. 22,020 16.3 1,959.5 281.0 144.0
TSS.............. 10/01/1971-09/30/1976................................ 1,826 30.0 2,900.0 365.1 350.7
06330000 Missouri River, Williston, ND Flow............. 10/01/1928-07/31/1965................................ 13,453 37.4 5,097.0 577.8 422.8
06338490 Missouri River, Garrison Dam Flow............. 10/01/1969-09/30/2007................................ 13,876 116.1 1,846.3 606.3 224.7
06342500 Missouri River, Bismarck, ND Flow............. 10/01/1927-present................................... 29,323 51.0 10,279.0 628.7 368.7
TSS.............. 10/01/1971-09/30/1981................................ 3,653 14.0 2,800.0 173.7 180.1 Tributaries06329500 Yellowstone River near Sidney MT Flow............. 10/01/1910-12/31/1931 10/01/1933-present............. 34,888 16.1 4,021.0 349.4 358.7
TSS.............. 06/18/1965; 10/03/1971-05/28/08...................... 426 10.0 15,500.0 900.0 1596.0
06340500 Knife River, at Hazen, ND Flow............. 04/01/1929-present................................... 28,798 ......... 634.3 4.3 19.6
TSS.............. 03/08/1946-07/31/1946 04/23/1948-09/30/1948.......... 292 29.0 6,900.0 441.4 882.3
06341410 Turtle Creek, above Washburn Flow............. 10/01/1986-09/30/2003................................ 6,209 ......... 21.7 0.4 0.9
06342260 Square Butte Creek, below Center, ND Flow............. 06/01/1965-present................................... 15,675 ......... 75.6 0.3 2.5
06342450 Burnt Creek, near Bismarck, ND Flow............. 10/01/1967-present................................... 11,656 ......... 110.4 0.3 2.1
06349000 Heart River, near Mandan, ND Flow............. 04/01/1924-present................................... 27,822 ......... 804.2 7.2 27.4
TSS.............. 10/01/1971-09/30/1976................................ 1,826 1.0 3,460.0 124.1 358.7
06349500 Apple Creek, near Menoken, ND Flow............. 03/01/1905-present................................... 22,891 ......... 158.3 1.2 4.9
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Data were retrieved from begin of record until June 15, 2008; Flow were continuous measured and TSS instantaneous. TSS--Total Suspended Solids
4.0 IDENTIFICATION OF AGGRADATION LOCATIONS IN THE MAINSTEM OF THE
MISSOURI RIVER
Prior to the identification of sources of erosion and sedimentation
(described in Section 5), Berger conducted an analysis of aggradation
areas within the main stem of the Missouri River using information from
three available key documents. Sediment deposit sites located upstream
from Garrison Dam were identified based on information from the
Aggradation, Degradation, and Water Quality Conditions report by USACE
(1993). Sediment deposit sites located between the Garrison Dam and the
city of Bismarck were identified based on information from the Missouri
River--Fort Peck Dam to Ponca State Park Geomorphological Assessment
Related to Bank Stabilization report by USACE (December 2001). Sediment
deposit sites located between the city of Bismarck and the downstream
boundary of this study (Figure 3-1) were identified based on
information from the Lake Oahe Aggradation Study by USACE (June 1993).
However, these reports were used to identify aggradation areas only in
longitudinal direction. As a result, the latitudinal extent of the
aggradation areas was randomly defined between bluff to bluff of the
Missouri River. The aggradation areas were classified in low, moderate,
and high in order to show qualitatively the magnitude of aggradation
(the classification was based on narrative and numeric description of
the magnitude of aggradation reported in the above quoted literature).
Sediment Aggregation Between ND-MT State Line and Garrison Dam
The USACE (1993) report compiled a record of available sediment-
related data and information that were collected at least 30 years ago
(between 1946 and 1989) by the USACE (Omaha District) and USGS on the
Missouri River in Montana, North Dakota, South Dakota, and Nebraska.
The report also provided an evaluation of changes in channel geometry
(channel width, average bed profile, thalweg profile, and cross-
sectional area) in order to analyze reservoir volume, bed material
gradation, stream bank erosion, and tailwater trends in terms of
aggradation and degradation.
Specifically, the thalweg profiles and the average bed profiles
developed between the North Dakota and Montana State line for 4
representative years (1956, 1964, 1978, and 1987) presented in the
USACE report were used by Berger to locate and estimate qualitatively
aggradation sites in this area. Based on this analysis, the largest
continuous area of sediment aggradation were found in the upstream ends
of Lake Sakakawea extending approximately over 94 miles between river
mile 1564 (approximately 22 miles downstream from the Yellowstone
River) and river mile 1470 (approximately 4 miles downstream from
Clarks Creek) (Figures 4-1 and 4-2). The highest level of aggradation
in this area were located between river mile 1534 and river mile 1521
shown in red in Figure 4-1. It should be noted that the presented
location of the aggradation areas needs to be verified with more
current measurements.
Sediment Aggradation Between Garrison Dam and the City of Bismarck
The USACE (Dec. 2001) report evaluated the potential impacts of
bank stabilization on the morphologic processes in the Missouri River.
The report analyzes four open stretches on the main stem of the
Missouri River (Fort Peck to vicinity of Yellowstone River, Garrison
Dam to Lake Oahe, Fort Randall Dam to the Niobrara River, and Gavins
Point Dam to Ponca). The analysis is based on an extensive field
investigation and data collection for sediment from banks, bars,
islands, and tributaries, and includes the establishment of
relationships between channel width and bars and islands, bar and
island density analysis, sediment gradation analysis, bank erosion
analysis, and sediment budget.
Specifically, the calculated net sediment transport presented in
the USACE (Dec. 2001) for the Garrison Reach was used by Berger to
locate and estimate qualitatively aggradation sites in this area. The
reported net sediment transport volumes were calculated for six
geomorphic reaches and were based on estimated volumes for erosion and
deposition at banks and beds between 1976 and 1998. Overall, the
Garrison reach is dominated by erosion with stream bed erosion playing
the major role. The largest erosion was found in the upper section of
the Garrison reach between Garrison Dam and river mile 1363. Downstream
from this section between river mile 1362 and 1363 (geomorphic reach
GR3), erosion decreased considerably which led to the only aggradation
area located within the Garrison Reach. Figure 4-3 depicts the location
of this aggregation area. The erosion in the remaining downstream
section between river mile 1352 and 1315 increased again and reached a
dynamic equilibrium in the last 24 miles (river mile 1339 to 1315) of
the Garrison Reach.
Sediment Aggradation Between the City of Bismarck and the Downstream
Boundary of This Study (Upper end of Lake Oahe)
The USACE (June 1993) compiled information on morphologic
conditions and trends for Lake Oahe using historic survey data
(profiles of the aggradation ranges, bed and suspended sediment data,
density of sediment deposits, pool elevation records, capacity and
sediment depletion data, and shoreline erosion information) collected
during eight surveys between 1958 and 1989.
Specifically, the profiles for average bed elevation profiles,
thalweg elevation, and average depth of sediment deposit presented in
the USACE report were used by Berger to locate and estimate
qualitatively aggradation sites in this area. Except for an
approximately 10 mile stretch downstream of the city of Bismarck,
aggradation areas were identified along the entire section (Figures 4-3
and 4-4). High amount of aggradation were found in four relatively
small stretches of approximately 5 miles long located at approximately
20 miles downstream from the city of Bismarck and upstream and
downstream of the confluence with the Grand River (RM 1190--1205). A
stretch of 31 miles located between RM 1248 and 1217 showed the largest
extent of medium aggradation (Figure 4-4).
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 4-1.--Aggradations Area Map--Lake Sakakawea upstream from
Garrison Dam through Williston, ND
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 4-2.--Aggradations Area Map--Lake Sakakawea upstream from
Garrison Dam through Ft. Berthold Indian Reservation
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 4-3.--Aggradations Area Map--Mainstem between Garrison Dam and
RM 1279
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 4-4.--Aggradations Area Map--Mainstem between RM 1279 and 1180
5.0 SEDIMENT SOURCE ASSESSMENT
Berger conducted an assessment of potential sediment sources for
the mainstem Missouri River in North Dakota. The purpose of this
assessment is to estimate approximate sediment loads of each potential
source delivered to the mainstem Missouri River in North Dakota and
approximate sediment loads produced within the mainstem Missouri River
in North Dakota (instream erosion loads from bed and banks). Potential
sediment sources are delivered from Missouri River in Montana, the
Yellowstone River watershed (largest watershed draining into the
Missouri River within North Dakota), from the remaining watersheds in
North Dakota draining into the Missouri River, and produced within the
area between Garrison Dam and the city of Bismarck of the Missouri
River. The delivered sediment loads from Montana and from the
Yellowstone River were obtained from sediment load estimates by USACE.
The delivered sediment loads from the remaining watersheds within North
Dakota were estimated using the planning-level tool Generalized
Watershed Loadings Functions (GWLF). The instream erosion loads were
estimated using USGS gaging data and the estimates from GWLF.
5.1 Delivered Sediment Load From Montana and the Yellowstone River
Based on Wuebben and Gagnon (1995), the USACE in 1978 estimated an
annual long-term sediment load for Missouri River at Culbertson,
Montana (USGS gage number 06185500, located approximately 20 miles
upstream from the Montana--North Dakota border) of approximately 13.5
million tons and for the Yellowstone River at Sidney, Montana (USGS
gage number 06329500, located approximately 20 miles upstream from the
confluence with the Missouri River) of approximately 41.5 million tons.
Both sediment loads are delivered into Lake Sakakawea. However, as
mentioned in Wueben and Gagnon (1995), based on a preliminary study by
the USGS, these loads may have been overestimated by 30-percent. The
USACE (1993a) estimated that the gross storage loss for all of Lake
Sakakawea since closure of the dam in 1953 and the survey date in 1988
was 907,000 acre-feet or 25,900 acre-feet/year. Using a bulk density of
1.4 g/cm3, based on values provided by Geiger (1963) for sand and silt,
this volume translates into a sediment supply of 45 million tons/year.
This volume is similar to the volume discussed above in Wuebben and
Gagnon (1995), after allowing for a 30 percent reduction as suggested.
Therefore, using this 30-percent reduction, the approximate annual
delivered sediment load from the Missouri River at Culbertson, Montana,
is 9.5 million tons and from the Yellowstone River at Sidney, Montana,
29.1 million tons.
5.2 Delivered Sediments From the Remaining Watersheds Within the Study
Area
Berger evaluated sediment sources for the remaining watersheds
draining into the Missouri River in North Dakota using a planning level
tool. The remaining watersheds included the HUC-8 watersheds Lake
Sakakawea, Little Muddy River, Upper Little Missouri River, Boxelder
Creek, Middle Little Missouri River, Beaver Creek, Lower Little
Missouri River, Painted Woods-Square Butte, Upper Lake Oahe, Apple
Creek, Beaver Creek Oahe, Knife River, Upper Heart, Lower Heart River,
Upper Cannonball River, Cedar Creek, and Lower Cannonball River. The
planning-level tool is the Generalized Watershed Loadings Functions
(GWLF). It is a time-variable simulation model that simulates hydrology
and land-based sediment loadings on a watershed basis. The objective
was to combine the data collected for these watersheds and to assess
and rank the land-based loads of sediments.
The following outlines the overall procedure used to assess the
sources of erosion in the remaining watersheds within the study area:
--The watershed was divided into HUC-10 segments (Figure 3-1). These
sub-watersheds served as the basis for developing the erosion
sources thematic map which shows the land-based sediment loads
for each sub-watershed.
--The planning tool was applied to the Knife River watershed to
estimate the delivered land based sediment unit-loads (tons per
hectare) to the Missouri River. The Knife River watershed
served as a prototype to verify the hydrology and generate the
reference land-based sediment loads by land use category. As a
result, the planning tool was validated for hydrology and
sediment loads.
--The reference land-based delivered sediment unit-loads, specific to
the Knife River; serve as a basis to develop the unit-loads in
each of the sub-watersheds. The Knife River unit-loads were
adjusted using the following HUC10 specific factors:
--Land use distribution in each of the HUC10 watersheds (Exhibit A)
--Soil erodibility (K factor)
--Field slope length and steepness (LS factor)
--Land cover management factor (C factor)
--Conservation practice factor (P factor)
--Sediment delivery ratios based on drainage area and total
delivered sediment load
5.2.1 Description of the Planning Tool--GWLF
The GWLF planning tool is a time variable model that simulates
hydrology and sediment loadings on a watershed basis. Observed daily
precipitation data is required in GWLF as the basis for water budget
calculations. Surface runoff, evapotranspiration and groundwater flows
are calculated based on user specified parameters. Stream flow is the
sum of surface runoff and groundwater discharge and was computed using
the Soil Conservation Service's Curve Number Equation. Curve numbers
are a function of soils and land use type. Evapotranspiration is
computed based on the method described by Hamon (1961) and is dependent
upon temperature, daylight hours, saturated water vapor pressure, and a
cover coefficient. Groundwater discharge to the stream was calculated
using a lumped parameter for unsaturated and shallow saturated water
zones. Infiltration to the unsaturated zone occurs when precipitation
exceeds surface runoff and evapotranspiration. Percolation to the
shallow saturated zone occurs when the unsaturated zone capacity is
exceeded. The shallow saturated zone is modeled as a linear reservoir
to calculate groundwater discharge. In addition, the model allows for
seepage to a deep saturated zone.
Erosion and sediment loading is a function of the land source areas
present in the watershed. Multiple source areas may be defined based on
land use type, the underlying soils type, and the management practices
applied to the lands. Sediment loads from each source area are summed
to obtain a watershed total. The Universal Soil Loss Equation (USLE) is
used to compute erosion for each source area and a sediment delivery
ratio is applied to determine the sediment loadings to the stream
(Wischmeier and Smith, 1978), and is expressed as:
A = R*K*LS*C*P
Where:
A = Average annual soil loss in tons per hectare per year
R = Rainfall/runoff erosivity
K = Soil erodibility
LS = Field slope length and steepness
C = Cover/management factor
P = Conservation practice factor.
The R factor is an expression of the erosivity of rainfall and
runoff in the area of interest; the R factor increases as the amount
and intensity of rainfall increases. The K factor represents the
inherent erodibility of the soils in the area of interest under
standard experimental conditions. The K factor is expressed as a
function of the particle-size distribution, organic-matter content,
structure, and permeability of the soils. The LS factor represents the
effect of topography, specifically field slope length and steepness, on
rates of soil loss at a particular site. The LS factor increases with
field slope length and steepness due to the resulting accumulation and
acceleration of surface runoff as it flows down slope. The C factor
represents the effects of surface cover and roughness, soil biomass,
and soil-disturbing activities on rates of soil loss at the area of
interest. The C factor decreases as surface cover and soil biomass
increase. The P factor represents the effects of supporting
conservation practices, such as contouring, buffer strips, and
terracing, on soil loss at the area of interest.
5.2.2 Application of the Planning Tool to the Knife River
This section presents and describes the setup and calibration of
the GWLF planning tool and the sediment loading estimates generated for
the Knife River. The tool was set up and validated for hydrology and
sediment by comparing model output to observed stream flow data and
published sediment loading data.
5.2.2.1 Model Set-Up
The GWLF planning tool requires two input files: a weather input
file (Weather.dat) and a transport input file (Transport.dat). The
weather input file requires daily precipitation data expressed in
centimeters and daily temperature data expressed in degrees Celsius.
The transport input file requires specification of input parameters
relating to hydrology, erosion, and sediment yield. Runoff curve
numbers and USLE erosion factors are specified as an average value for
a given source area. The existing and projected land cover
classifications present in the study area (Section 4) were used to
define model source areas. A total of 16 source areas were defined in
modeling the land cover conditions in the study area. As necessary, GIS
analyses were employed to obtain area-weighted parameter values for
each given source area.
Runoff curve numbers were developed for each model source area in
the study area based on values published in the NRCS Technical Release
55 (NRCS, 1986). STATSGO soils GIS coverages were analyzed to determine
the dominant soil hydrologic groups for each model source area.
Evapotranspiration cover coefficients were developed based on values
provided in the GWLF manual (Haith et al., 1992) for each model source
area. Average watershed monthly evapotranspiration cover coefficients
were computed based on an area-weighted method. Initialization of
groundwater hydrology and other parameters were set to default values
recommended in the GWLF manual.
USLE factors for soil erodibility (K), length-slope (LS), cover and
management (C), and supporting practice (P) were derived from multiple
sources based on data availability. KLSCP factors were obtained from
the revised 1997 National Resources Inventory (NRI) database provided
by the NRCS. Otherwise, average K, LS, C, and P values for model source
areas were determined based on GIS analysis of soils and topographic
coverages, and literature review. The rainfall erosivity coefficient
was determined from values given in the GWLF manual. The sediment
delivery ratio was computed directly in the GWLF model interface.
Developed lands include impervious surfaces that are not subject to
soil erosion. Therefore, sediment loads from developed lands were not
modeled using the USLE. Instead, sediment loads from developed lands
were computed based on typical loading rates from developed lands
(Horner et al., 1994).
5.2.2.2 Hydrology Calibration in the Knife River Watershed
GWLF was originally developed as a planning tool for estimating
nutrient and sediment loadings on a watershed basis. Designers of the
model intended for it to be implemented without calibration.
Nonetheless, comparisons were made between predicted and observed
stream flow collected in the study area to ensure the general validity
of the model.
Daily stream flow data were available at one USGS station
(06340500) located in the study area (Figure 3-1). The groundwater
seepage coefficient, base flow recession coefficient, and unsaturated
zone available water capacity were adjusted using an iterative approach
in order to obtain a best fit with observed data.
Results of the hydrology verification are presented in Figures 5-1
and 5-2. Figure 5-1 depicts the monthly observed and simulated flows
and Figure 5-2 shows the stream flow verification statistics. Total
flow volume was under-predicted by approximately 13 percent. The GWLF
model predicted fairly well the observed flow in the Knife River
indicated by the robustness of the regression with an R-square of 0.87.
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 5-1.--Hydrology Verification for the Knife River--Observed and
Simulated Flow
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 5-2.--Hydrology Verification for the Knife River--Regression
between Observed and Simulated Flows
5.2.2.3 Sediment Loads Verification in the Knife River Watershed
The objective of the sediment verification was to insure that the
sediment loads (erosion rates or edge of stream loads) were within
acceptable published values. As a guideline, published literature
values of expected erosion rates (Donigian, 2003) were used. Table 5-1
depicts the results of the simulated erosion rates in the Knife River
watershed as they compared to the published values.
TABLE 5-1.--SIMULATED EROSION RATES BY LAND COVER TYPE IN THE KNIFE RIVER WATERSHED
----------------------------------------------------------------------------------------------------------------
Simulated Erosion Rates (tons/
Published ha)
Land Use Type Values (tons/ -------------------------------
ha) MEAN STDEV MIN MAX
----------------------------------------------------------------------------------------------------------------
Mixed Forest.................................................... 0.1-0.9 0.29 0.16 0.11 0.51
Grassland/Herbaceous............................................ 0.35-1.9 0.82 0.46 0.33 1.47
Pasture/Hay..................................................... 0.7-3.8 1.53 0.86 0.61 2.73
Cultivated Crop \1\............................................. 1.6-12.3 3.67 2.07 1.45 6.55
Barren Land..................................................... > 15.0 5.05 2.85 2.00 9.00
Developed, Low intensity........................................ 0.4-2.2 0.27 0.15 0.11 0.49
Developed, Med Intensity........................................ 0.4-2.2 0.32 0.18 0.13 0.57
Developed, High Intensity....................................... 0.4-2.2 0.38 0.22 0.15 0.68
Developed, Open Space........................................... 0.4-2.2 0.40 0.22 0.16 0.71
----------------------------------------------------------------------------------------------------------------
\1\ Average sediment loads from conventional and low-till land uses.
The typical erosion rates presented in Table 5-1 were used as
verification guidelines to insure that the simulated erosion rates were
within acceptable published values. These sediment loads from the Knife
River serve as the basis to estimate the sediment loads from the
remaining watersheds.
5.2.3 Sediment Load Assessment for the Remaining Sub-Watersheds
The reference land-based delivered sediment unit-loads presented in
the previous section served as a basis to develop the unit-loads in
each of the sub-watersheds. In the first step, the sediment unit-loads
were applied to the land use distribution in each of the sub-
watersheds. Then the estimated sediment loads were adjusted using the
specific K, LS, C, and P factors of the prototype watershed (Knife
River) and each sub-watershed. This initial adjustment accounted for
the differences between the Knife River watershed and each sub-
watershed in terms of the USLE factors including: soil erodibility (K
factor), field slope length and steepness (LS factor), land cover
management factor (C factor), and the conservation practice factor (P
factor) The USLE factors were obtained from the revised 1997 NRI
database.
The derived sediment loads from each sub-watershed were then
adjusted to derive the sediment loads delivered to the Missouri River.
Sediment delivery ratios were estimated for each sub-watershed based on
the size of the drainage area using a method published by McCuen (1998)
for Midwestern watersheds:
SDL = 64.6 * A-0.2775(100 A 1000mi\2\)
SDL = Sediment Delivery ratio (%)
A = Drainage Area (mi\2\)
The estimated land-based sediment loads delivered to the Missouri
River in North Dakota from each of the sub-watersheds were used to
develop a thematic map using GIS. Figure 5-3 shows the thematic map of
the land-based delivered sediments to the main stem of the Missouri
River from each sub-watershed. The results revealed that the largest
portion of the delivered sediment loads originated from the northern
and center sections of the study area. These areas also contained the
largest percentage of land cover devoted to cultivated crops in the
study area that is prone to soil erosion (Figure 3-2). The calculated
total delivered sediment load was then used to rank each of the sub-
watersheds (HUC08) based on loads (Table 5-2). As a result of this
analysis, the highest delivered sediment load to the Missouri River
originated from the Lake Sakakawea watershed that accounts for
approximately 29-percent of the total delivered land based sediment
load.
TABLE 5-2.--DELIVERED SEDIMENT LOAD TO THE MISSOURI RIVER FROM EACH WATERSHED (HUC08)
----------------------------------------------------------------------------------------------------------------
Sediment Load delivered to the
Missouri River
-------------------------------
Watershed HUC08 Fraction of
metric tons/ the total
year delivered load
(percent)
----------------------------------------------------------------------------------------------------------------
Lake Sakakawea................................. 10110101....................... 496,447 28.7
Painted Woods--Square Butte.................... 10130101....................... 159,527 9.2
Knife River.................................... 10130201....................... 150,124 8.7
Upper Cannonball River......................... 10130204....................... 126,027 7.3
Upper Heart.................................... 10130202....................... 105,946 6.1
Lower Heart River.............................. 10130203....................... 102,731 5.90
Upper Lake Oahe................................ 10130102....................... 94,924 5.5
Little Muddy River............................. 10110102....................... 91,445 5.3
Middle Little Missouri River................... 10110203....................... 88,971 5.1
Cedar Creek.................................... 10130205....................... 74,852 4.3
Apple Creek.................................... 10130103....................... 53,657 3.1
Upper Little Missouri River.................... 10110201....................... 49,194 2.8
Beaver Creek................................... 10110204....................... 38,660 2.2
Upper Cannonball River......................... 10130204....................... 33,356 1.9
Beaver Oahe Creek.............................. 10130104....................... 32,153 1.9
Boxelder Creek................................. 10110202....................... 25,350 1.5
Lower Little Missouri River.................... 10110205....................... 7,280 0.4
-------------------------------
Total delivered land based load.......... ............................... 1,730,644 100.0
----------------------------------------------------------------------------------------------------------------
5.3 Produced Instream Erosion in the Mainstem of the Missouri River
Between Garrison Dam and the City of Bismarck
Based on the analysis in section 4 of this report and additional
studies by USACE (2008) and USGS (1995), the mainstem reach between
Garrison Dam and the city of Bismarck is the only segment in the
mainstem of the Missouri River of North Dakota in which instream
erosion dominates. The total instream erosion load for this reach was
estimated by subtracting the total annual sediment load at the USGS
Bismarck gaging station (USGS 06342500) from the sediment load
delivered by sub-watersheds that drain into the Missouri River between
Garrison Dam and the city of Bismarck; the sediment load delivered from
Garrison Dam was deemed to be insignificant. The total annual sediment
load was estimated using all available flow and TSS measurements (1971-
1981) at USGS 06342500 (Table 3-6) and a 10 percent adjustment to
account for bedload (USGS, 1995). The total sediment load delivered
from the sub-watersheds draining into the Missouri River between
Garrison Dam and the city of Bismarck was estimated based on estimates
provided in Table 5-2. This analysis resulted in a total instream
erosion load of 4.7 million tons/year and accounts for 90 percent of
the total sediment load produced between Garrison Dam and the City of
Bismarck.
5.4 Summary of Sediment Loads in the Missouri River Within North Dakota
Based on the sediment load assessment conducted in Section 5.1,
5.2, and 5.3, the Yellowstone River and the Missouri River in Montana
delivered the largest fraction of sediment loads to the main stem
Missouri River in North Dakota. The Yellowstone River and the Missouri
River in Montana accounted for more than 86 percent of the total
delivered load whereas the watersheds within the study area (not
including the Yellowstone River watershed) accounted only for
approximately 4 percent of the total delivered load in North Dakota.
Sediment load from instream erosion within the Missouri River accounted
for more than 10 percent. Table 5-3 summarizes the sediment loads and
their fractions.
TABLE 5-3.--SEDIMENT LOADS AND THEIR FRACTIONS IN THE MISSOURI RIVER, ND
------------------------------------------------------------------------
Estimated Sediment
Load of the
mainstem of the Fraction of Total
Source Missouri River Delivered Sediment
within North Load (percent)
Dakota (million
tons/year)
------------------------------------------------------------------------
Yellowstone River \1\........... 29.1 64.7
Missouri River from Montana \2\. 9.5 21.1
Watersheds within the Study Area 1.7 3.8
\3\............................
Instream Erosion within the 4.7 10.4
Garrison Reach \4\.............
---------------------------------------
Total \5\................. 45.0 100.0
------------------------------------------------------------------------
\1\ Based on estimated sediment loads by USACE at USGS station 06185500
(Missouri River at Culbertson, Montana) and reduction of 30 percent.
\2\ Based on estimated sediment loads by USACE at USGS station 06329500
(Yellowstone River at Sidney, Montana) and reduction of 30 percent.
\3\ Based on 5 year average sediment load using GWLF; Includes all
watersheds draining into the Missouri River in North Dakota except for
the Yellowstone River.
\4\ Based on the difference between the total annual sediment load at
USGS 06342500 and the total delivered sediment load of the four sub-
watersheds draining between Garrison Dam and the city of Bismarck.
\5\ Sum of delivered sediment load to the mainstem of the Missouri River
within North Dakota and produced sediment within the Garrison Reach
(Missouri River mainstem between Garrison Dam and the City of
Bismarck).
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 5-3.--Thematic Map of the Sediments Delivered to the Missouri
River
6.0 LINKAGE BETWEEN AGGRADATION AREAS AND SEDIMENT SOURCES
The main stem of Missouri River located between the North Dakota--
Montana state line and Lake Oahe was analyzed to determine whether the
identified aggradation areas presented in Section 4 could be linked to
sediment sources delivered from Montana and from 201 sub-watersheds in
North Dakota presented in Section 5. Figure 6-1 shows the identified
aggradation areas and delivered sediment to the main stem of the
Missouri River from Montana and from each sub-watershed within the
study area. The following conclusions can be drawn from this analysis.
--The majority of the identified aggradation areas were located
upstream of Lake Sakakawea in the close vicinity to the
Montana/North Dakota border and in the vicinity of watersheds
that showed large amounts of delivered land-based sediments. It
appears that the aggradation areas were predominantly caused by
the delivered sediment loads from the Yellowstone River and the
Missouri River in Montana when the proportions of estimated
delivered sediment load are compared to each other (Table 5-3).
--The area between the city of Bismarck and Lake Oahe showed several
aggradation areas with mostly low and moderate aggradation.
Potential sources for sediment deposition were sediment erosion
from instream erosion caused by hydropower at Garrison Dam and
delivered land-based sediments from the Painted Woods Square
Butts, Knife River, Heart River, and Cannonball River
watersheds. The largest source of these aggradation areas are
likely sediment deposits from eroded riverbed and riverbank
sediments due to the impact of hydropower use at Garrison Dam.
--Areas that showed little or no aggradation were generally located
within the center of the lakes (Lake Sakakawea and Lake Oahe)
and in the stream reach between Garrison Dam and the city of
Bismarck in which instream erosion dominates (90 percent of the
total sediment load originates from instream erosion).
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 6-1.--Sediment Aggradation Areas and Amount of Delivered
Sediment from each Sub-watershed
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McCuen, R.H. 1998. Hydrologic Analysis and Design. Prentice Hall,
Inc. Upper Saddle River, New Jersey 07458.
Mutua, B.M. and A. Klik. 2006. Estimating Spatial Sediment Delivery
Ratio on a Large Rural Catchment. Journal of Spatial Hydrology Vol.6,
No.1 Spring 2006.
Ouyang, D. and J. Bartholic. 1997. Predicting Sediment Delivery
Ratio in Saginaw Bay Watershed. Institute of Water Research, Michigan
State University, East Lansing, MI.
Shields, F.D., Simon, A., and L.J. Steffen. 2000. Reservoir Effects
on Downstream River Channel Migration. Environmental Conservation 27
(1): 54-66.
USACE (Garrison, Omaha, and Cansas City Districts). 1957.
Degradation Below Garrison Dam: Observations in 1954. U.S. Army Corps
of Engineers.
USACE (Omaha District). 1980. Verification of Sediment Transport
Functions: Missouri River.
USACE (Omaha District). 1984. Aggradation and Degradation Aspects
of the Missouri River Mainstem Dams. U.S. Army Corps of Engineers.
USACE (Omaha District). 1992. Bank Recession. U.S. Army Corps of
Engineers.
USACE (Omaha District). 1993. Aggradation, Degradation, and Water
Quality Conditions: Missouri River Mainstem Reservoir System. U.S. Army
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USACE (Omaha District). 1993. Downstream Channel and Sediment
Trends Study. U.S. Army Corps of Engineers.
USACE (Omaha District). June 1993. Lake Oahe Aggradation Study.
Volume 1, Sections I-XII, Appendices I-IV. Prepared by Resource
Consultants, Inc. for U.S. Army Corps of Engineers, Omaha District.
USACE (Northwestern Division, Reservoir Control Center). 1999.
Missouri River Mainstem Reservoirs 1998-1999 Annual Operating Plan.
U.S. Army Corps of Engineers.
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USDA. December 2001. Missouri River--Fort Peck Dam to Ponca State
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Authors: D.S. Biedenharn, R.S. Soileau, L.C. Hubbard, and P.H. Hoffmann
(U.S. Army Engineer Research and Development Center); C.R. Thorne and
C.C. Bromley (University of Nottingham); C.C. Watson (Colorado State
University). U.S. Army Corps of Engineers.
USACE (Omaha District). 2008. Bank Stabilization Cumulative Impact
Analysis Final Technical Report. U.S. Army Corps of Engineers.
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Watersheds. U.S. Department of Agriculture.
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(Revised December 2000). United States Department of Agriculture.
USDA. 2001. The 1997 National Resources Inventory (revised December
2000) A GUIDE FOR USERS OF 1997 NRI DATA FILES CD-ROM Version 1. United
States Department of Agriculture, Natural Resources Conservation
Service.
USGS. 1992. Techniques for Estimating Peak Flow Frequency Relations
for North Dakota Streams. U.S. Geological Survey.
USGS. 1995. Transport and Sources of Sediment in the Missouri River
between Garrison Dam and the Headwaters of Lake Oahe, North Dakota, May
1988 through April 1991. U.S. Geological Survey.
USGS. 2000. Suspended-Sediment Loads from Major Tributaries to the
Missouri River between Garrison Dam and Lake Oahe, North Dakota, 1954-
98. U.S. Geological Survey.
USGS. 2006. Water, Bed-Sediment, and Fish-Tissue Quality within the
Standing Rock Sioux Reservation, North Dakota and South Dakota. U.S.
Geological Survey.
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Statewide Monitoring Network, 1999-2003. Scientific Investigation
Report 2006-5046. U.S. Geological Survey.
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Coefficient and Event Mean concentration (EMC) Data. Lin, J.P. 2004.
Wetlands Regulatory Assistance Program. ERDC TN WRAP-O4-3.
Vanoni, V. A. 2006. ASCE Manuals and Reports on Engineering
Practice No. 54: Sedimentation Engineering. American Society of
Engineers.
Walling, D.E.1983. The Sediment Delivery Problem. Journal of
Hydrology, 65, 209-237.
Williams, J.R. 1977. Sediment delivery ratios determined with
sediment and runoff models. Proceedings Symposium on Erosion and Solid
Matter Transport in Inland Water. International Association
Hydrological Science, No. 122, 168-179.
Wischmeier, W.H. and D.D. Smith. 1978. Predicting Rainfall Erosion
Losses--A Guide to Conservation Planning. USDA Handbook 537.
Washington, DC: U.S. GPO.
Wuebben, J.L. and J.J. Gagnon, 1995. Ice jam flooding on the
Missouri River near Williston, North Dakota. Accessed at: http://
www.tpub.com/content/ArmyCRREL/CR95_19/CR95_190007.htm.
exhibit a
Table A-1 through A-18: Land Use Distribution for the Yellowstone
River Watershed and each HUC8 Watersheds within the Study Area.
TABLE A-1.--LAND USE DISTRIBUTION OF THE YELLOWSTONE RIVER WATERSHED
------------------------------------------------------------------------
NLCD Land Use Type Hectare Percent
------------------------------------------------------------------------
Open Water.................................... 68,614 0.84
Developed, Open Space......................... 49,780 0.61
Developed, Low Intensity...................... 18,155 0.22
Developed, Medium Intensity................... 2,958 0.04
Developed, High Intensity..................... 433 0.01
Barren Land (Rock/Sand/Clay).................. 127,428 1.56
Deciduous Forest.............................. 17,209 0.21
Evergreen Forest.............................. 1,323,268 16.17
Mixed Forest.................................. 4,332 0.05
Shrub......................................... 3,367,598 41.15
Grassland/Herbaceous.......................... 2,578,292 31.50
Pasture/Hay................................... 211,442 2.58
Cultivated Crops.............................. 264,217 3.23
Woody Wetlands................................ 84,425 1.03
Emergent Herbaceous Wetlands.................. 57,212 0.70
Perennial Ice/Snow............................ 8,417 0.10
-------------------------
Total................................... 8,175,362 100.00
------------------------------------------------------------------------
TABLE A-2.--LAND USE DISTRIBUTION OF THE LAKE SAKAKAWEA WATERSHED (HUC
10110101)
------------------------------------------------------------------------
NLCD Land Use Type Hectare Percent
------------------------------------------------------------------------
Open Water................................... 151,781 8.90
Developed, Open Space........................ 52,092 3.06
Developed, Low Intensity..................... 5,018 0.29
Developed, Medium Intensity.................. 591 0.03
Developed, High Intensity.................... 107 0.010
Barren Land (Rock/Sand/Clay)................. 7,611 0.45
Deciduous Forest............................. 37,138 2.18
Evergreen Forest............................. 1,207 0.07
Mixed Forest................................. 2,968 0.17
Shrub........................................ 23,126 1.36
Grassland/Herbaceous......................... 639,752 37.52
Pasture/Hay.................................. 24,466 1.43
Cultivated Crops............................. 705,176 41.36
Woody Wetlands............................... 11,687 0.69
Emergent Herbaceous Wetlands................. 42,270 2.48
--------------------------
Total.................................. 1,704,993 100.00
------------------------------------------------------------------------
TABLE A-3.--LAND USE DISTRIBUTION OF THE LITTLE MUDDY RIVER WATERSHED
(HUC 10110102)
------------------------------------------------------------------------
NLCD Land Use Type Hectare Percent
------------------------------------------------------------------------
Open Water.................................... 3,452 1.46
Developed, Open Space......................... 9,512 4.03
Developed, Low Intensity...................... 377 0.16
Developed, Medium Intensity................... 29 0.01
Developed, High Intensity..................... 3 ...........
Barren Land (Rock/Sand/Clay).................. 46 0.02
Deciduous Forest.............................. 232 0.10
Evergreen Forest.............................. 16 0.01
Mixed Forest.................................. 31 0.01
Shrub......................................... 3,303 1.40
Grassland/Herbaceous.......................... 51,703 21.89
Pasture/Hay................................... 740 0.31
Cultivated Crops.............................. 161,623 68.44
Woody Wetlands................................ 670 0.28
Emergent Herbaceous Wetlands.................. 4,412 1.87
-------------------------
Total................................... 236,148 100.00
------------------------------------------------------------------------
TABLE A-4.--LAND USE DISTRIBUTION OF THE UPPER LITTLE MISSOURI RIVER
WATERSHED (HUC 10110201)
------------------------------------------------------------------------
NLCD Land Use Type Hectare Percent
------------------------------------------------------------------------
Open Water.................................... 566 0.06
Developed, Open Space......................... 3,960 0.45
Developed, Low Intensity...................... 483 0.05
Developed, Medium Intensity................... 14 ...........
Developed, High Intensity..................... 1 ...........
Barren Land (Rock/Sand/Clay).................. 1,729 0.19
Deciduous Forest.............................. 686 0.08
Evergreen Forest.............................. 30,083 3.39
Mixed Forest.................................. 1 ...........
Shrub......................................... 284,486 32.02
Grassland/Herbaceous.......................... 514,185 57.88
Pasture/Hay................................... 1,710 0.19
Cultivated Crops.............................. 40,017 4.50
Woody Wetlands................................ 4,165 0.47
Emergent Herbaceous Wetlands.................. 6,316 0.71
-------------------------
Total................................... 888,402 100.00
------------------------------------------------------------------------
TABLE A-5.--LAND USE DISTRIBUTION OF THE BOXELDER CREEK WATERSHED (HUC
10110202)
------------------------------------------------------------------------
NLCD Land Use Type Hectare Percent
------------------------------------------------------------------------
Open Water.................................... 219 0.07
Developed, Open Space......................... 563 0.18
Developed, Low Intensity...................... 130 0.04
Developed, Medium Intensity................... ........... ...........
Developed, High Intensity..................... ........... ...........
Barren Land (Rock/Sand/Clay).................. 324 0.11
Deciduous Forest.............................. 218 0.07
Evergreen Forest.............................. 8,069 2.62
Mixed Forest.................................. ........... ...........
Shrub......................................... 82,732 26.84
Grassland/Herbaceous.......................... 197,962 64.21
Pasture/Hay................................... 116 0.04
Cultivated Crops.............................. 14,232 4.62
Woody Wetlands................................ 2,246 0.73
Emergent Herbaceous Wetlands.................. 1,484 0.48
-------------------------
Total................................... 308,294 100.00
------------------------------------------------------------------------
TABLE A-6.--LAND USE DISTRIBUTION OF THE MIDDLE LITTLE MISSOURI RIVER
WATERSHED (HUC 10110203)
------------------------------------------------------------------------
NLCD Land Use Type Hectare Percent
------------------------------------------------------------------------
Open Water................................... 3,410 0.61
Developed, Open Space........................ 7,332 1.30
Developed, Low Intensity..................... 777 0.14
Developed, Medium Intensity.................. 15 ...........
Developed, High Intensity.................... 0.4 ...........
Barren Land (Rock/Sand/Clay)................. 7,542 1.34
Deciduous Forest............................. 16,637 2.95
Evergreen Forest............................. 8,621 1.53
Mixed Forest................................. 2,288 0.41
Shrub........................................ 61,781 10.96
Grassland/Herbaceous......................... 354,883 62.98
Pasture/Hay.................................. 13,986 2.48
Cultivated Crops............................. 81,856 14.53
Woody Wetlands............................... 3,475 0.62
Emergent Herbaceous Wetlands................. 921 0.16
--------------------------
Total.................................. 563,524 100.00
------------------------------------------------------------------------
TABLE A-7.--LAND USE DISTRIBUTION OF THE BEAVER CREEK WATERSHED (HUC
10110204)
------------------------------------------------------------------------
NLCD Land Use Type Hectare Percent
------------------------------------------------------------------------
Open Water.................................... 278 0.12
Developed, Open Space......................... 5,040 2.23
Developed, Low Intensity...................... 675 0.30
Developed, Medium Intensity................... 73 0.03
Developed, High Intensity..................... 4 ...........
Barren Land (Rock/Sand/Clay).................. 1,796 0.79
Deciduous Forest.............................. 2,926 1.29
Evergreen Forest.............................. 1,591 0.70
Mixed Forest.................................. 418 0.18
Shrub......................................... 14,944 6.60
Grassland/Herbaceous.......................... 112,922 49.87
Pasture/Hay................................... 11,595 5.12
Cultivated Crops.............................. 71,494 31.58
Woody Wetlands................................ 2,155 0.95
Emergent Herbaceous Wetlands.................. 508 0.22
-------------------------
Total................................... 226,420 100.00
------------------------------------------------------------------------
TABLE A-8.--LAND USE DISTRIBUTION OF THE LOWER LITTLE MISSOURI RIVER
WATERSHED (HUC 10110205)
------------------------------------------------------------------------
NLCD Land Use Type Hectare Percent
------------------------------------------------------------------------
Open Water.................................... 7,970 1.70
Developed, Open Space......................... 3,635 0.78
Developed, Low Intensity...................... 710 0.15
Developed, Medium Intensity................... 38 0.01
Developed, High Intensity..................... 4 ...........
Barren Land (Rock/Sand/Clay).................. 15,876 3.39
Deciduous Forest.............................. 58,399 12.48
Evergreen Forest.............................. 9,763 2.09
Mixed Forest.................................. 5,671 1.21
Shrub......................................... 38,440 8.21
Grassland/Herbaceous.......................... 260,691 55.71
Pasture/Hay................................... 9,011 1.93
Cultivated Crops.............................. 49,411 10.56
Woody Wetlands................................ 4,990 1.07
Emergent Herbaceous Wetlands.................. 3,330 0.71
-------------------------
Total................................... 467,939 100.00
------------------------------------------------------------------------
TABLE A-9.--LAND USE DISTRIBUTION OF THE PAINTED WOODS-SQUARE BUTTE
WATERSHED (HUC 10130101)
------------------------------------------------------------------------
NLCD Land Use Type Hectare Percent
------------------------------------------------------------------------
Open Water.................................... 29,657 4.62
Developed, Open Space......................... 24,365 3.79
Developed, Low Intensity...................... 1,899 0.30
Developed, Medium Intensity................... 307 0.05
Developed, High Intensity..................... 21 ...........
Barren Land (Rock/Sand/Clay).................. 813 0.13
Deciduous Forest.............................. 8,259 1.29
Evergreen Forest.............................. 52 0.01
Mixed Forest.................................. 53 0.01
Shrub......................................... 324 0.05
Grassland/Herbaceous.......................... 267,816 41.71
Pasture/Hay................................... 58,377 9.09
Cultivated Crops.............................. 204,979 31.92
Woody Wetlands................................ 17,615 2.74
Emergent Herbaceous Wetlands.................. 27,564 4.29
-------------------------
Total................................... 642,103 100.00
------------------------------------------------------------------------
TABLE A-10.--LAND USE DISTRIBUTION OF THE UPPER LAKE OAHE WATERSHED (HUC
10130102)
------------------------------------------------------------------------
NLCD Land Use Type Hectare Percent
------------------------------------------------------------------------
Open Water.................................... 59,833 6.55
Developed, Open Space......................... 19,825 2.17
Developed, Low Intensity...................... 3,306 0.36
Developed, Medium Intensity................... 740 0.08
Developed, High Intensity..................... 262 0.03
Barren Land (Rock/Sand/Clay).................. 2,429 0.27
Deciduous Forest.............................. 6,871 0.75
Evergreen Forest.............................. 125 0.01
Mixed Forest.................................. 82 0.01
Shrub......................................... 1,420 0.16
Grassland/Herbaceous.......................... 606,052 66.34
Pasture/Hay................................... 38,323 4.19
Cultivated Crops.............................. 152,196 16.66
Woody Wetlands................................ 9,059 0.99
Emergent Herbaceous Wetlands.................. 13,036 1.43
-------------------------
Total................................... 913,559 100.00
------------------------------------------------------------------------
TABLE A-11.--LAND USE DISTRIBUTION OF THE APPLE CREEK WATERSHED (HUC
10130103)
------------------------------------------------------------------------
NLCD Land Use Type Hectare Percent
------------------------------------------------------------------------
Open Water................................... 71,174 7.95
Developed, Open Space........................ 28,751 3.21
Developed, Low Intensity..................... 2,643 0.30
Developed, Medium Intensity.................. 706 0.08
Developed, High Intensity.................... 189 0.02
Barren Land (Rock/Sand/Clay)................. 323 0.04
Deciduous Forest............................. 344 0.04
Evergreen Forest............................. 18 ............
Mixed Forest................................. 23 ............
Shrub........................................ 523 0.060
Grassland/Herbaceous......................... 509,259 56.87
Pasture/Hay.................................. 71,997 8.04
Cultivated Crops............................. 172,864 19.30
Woody Wetlands............................... 527 0.06
Emergent Herbaceous Wetlands................. 36,198 4.04
--------------------------
Total.................................. 895,537 100.00
------------------------------------------------------------------------
TABLE A-12.--LAND USE DISTRIBUTION OF THE BEAVER OAHE WATERSHED (HUC
10130104)
------------------------------------------------------------------------
NLCD Land Use Type Hectare Percent
------------------------------------------------------------------------
Open Water.................................... 7,883 2.98
Developed, Open Space......................... 8,631 3.26
Developed, Low Intensity...................... 1,049 0.40
Developed, Medium Intensity................... 159 0.06
Developed, High Intensity..................... 40 0.02
Barren Land (Rock/Sand/Clay).................. 270 0.10
Deciduous Forest.............................. 208 0.08
Evergreen Forest.............................. 2 ...........
Mixed Forest.................................. ........... ...........
Shrub......................................... 2,005 0.76
Grassland/Herbaceous.......................... 151,276 57.16
Pasture/Hay................................... 27,906 10.54
Cultivated Crops.............................. 64,086 24.21
Woody Wetlands................................ 225 0.08
Emergent Herbaceous Wetlands.................. 933 0.35
-------------------------
Total................................... 264,671 100.00
------------------------------------------------------------------------
TABLE A-13.--LAND USE DISTRIBUTION OF THE KNIFE RIVER WATERSHED (HUC
10130201)
------------------------------------------------------------------------
NLCD Land Use Type Hectare Percent
------------------------------------------------------------------------
Open Water.................................... 1,827 0.28
Developed, Open Space......................... 17,360 2.68
Developed, Low Intensity...................... 1,578 0.24
Developed, Medium Intensity................... 199 0.03
Developed, High Intensity..................... 44 0.01
Barren Land (Rock/Sand/Clay).................. 607 0.09
Deciduous Forest.............................. 8,573 1.32
Evergreen Forest.............................. 315 0.05
Mixed Forest.................................. 176 0.03
Shrub......................................... 5,291 0.82
Grassland/Herbaceous.......................... 371,983 57.34
Pasture/Hay................................... 51,626 7.96
Cultivated Crops.............................. 181,352 27.95
Woody Wetlands................................ 6,354 0.98
Emergent Herbaceous Wetlands.................. 1,484 0.23
-------------------------
Total................................... 648,771 100.00
------------------------------------------------------------------------
TABLE A-14.--LAND USE DISTRIBUTION OF THE UPPER HEART WATERSHED (HUC
10130202)
------------------------------------------------------------------------
NLCD Land Use Type Hectare Percent
------------------------------------------------------------------------
Open Water.................................... 2,667 0.60
Developed, Open Space......................... 16,584 3.73
Developed, Low Intensity...................... 3,026 0.68
Developed, Medium Intensity................... 567 0.13
Developed, High Intensity..................... 60 0.01
Barren Land (Rock/Sand/Clay).................. 1,095 0.25
Deciduous Forest.............................. 1,200 0.27
Evergreen Forest.............................. 56 0.01
Mixed Forest.................................. 45 0.01
Shrub......................................... 2,354 0.53
Grassland/Herbaceous.......................... 178,175 40.08
Pasture/Hay................................... 45,944 10.33
Cultivated Crops.............................. 187,860 42.26
Woody Wetlands................................ 4,584 1.03
Emergent Herbaceous Wetlands.................. 349 0.08
-------------------------
Total................................... 444,566 100.00
------------------------------------------------------------------------
TABLE A-15.--LAND USE DISTRIBUTION OF THE LOWER HEART RIVER WATERSHED
(HUC 10130203)
------------------------------------------------------------------------
NLCD Land Use Type Hectare Percent
------------------------------------------------------------------------
Open Water.................................... 2,296 0.54
Developed, Open Space......................... 14,194 3.36
Developed, Low Intensity...................... 1,538 0.36
Developed, Medium Intensity................... 271 0.06
Developed, High Intensity..................... 31 0.01
Barren Land (Rock/Sand/Clay).................. 605 0.14
Deciduous Forest.............................. 6,180 1.46
Evergreen Forest.............................. 61 0.01
Mixed Forest.................................. 56 0.01
Shrub......................................... 915 0.22
Grassland/Herbaceous.......................... 217,000 51.30
Pasture/Hay................................... 29,785 7.04
Cultivated Crops.............................. 141,800 33.52
Woody Wetlands................................ 7,183 1.70
Emergent Herbaceous Wetlands.................. 1,113 0.26
-------------------------
Total................................... 423,027 100.00
------------------------------------------------------------------------
TABLE A-16.--LAND USE DISTRIBUTION OF THE UPPER CANNONBALL RIVER
WATERSHED (HUC 10130204)
------------------------------------------------------------------------
NLCD Land Use Type Hectare Percent
------------------------------------------------------------------------
Open Water.................................... 1,324 0.31
Developed, Open Space......................... 14,097 3.33
Developed, Low Intensity...................... 860 0.20
Developed, Medium Intensity................... 31 0.01
Developed, High Intensity..................... 4 ...........
Barren Land (Rock/Sand/Clay).................. 332 0.08
Deciduous Forest.............................. 997 0.24
Evergreen Forest.............................. 108 0.03
Mixed Forest.................................. 17 ...........
Shrub......................................... 1,037 0.24
Grassland/Herbaceous.......................... 139,550 32.93
Pasture/Hay................................... 57,497 13.57
Cultivated Crops.............................. 204,153 48.17
Woody Wetlands................................ 3,103 0.73
Emergent Herbaceous Wetlands.................. 718 0.17
-------------------------
Total................................... 423,827 100.00
------------------------------------------------------------------------
TABLE A-17.--LAND USE DISTRIBUTION OF THE CEDAR CREEK WATERSHED (HUC
10130205)
------------------------------------------------------------------------
NLCD Land Use Type Hectare Percent
------------------------------------------------------------------------
Open Water.................................... 1,453 0.32
Developed, Open Space......................... 12,952 2.82
Developed, Low Intensity...................... 564 0.12
Developed, Medium Intensity................... 8 ...........
Developed, High Intensity..................... 2 ...........
Barren Land (Rock/Sand/Clay).................. 219 0.05
Deciduous Forest.............................. 662 0.14
Evergreen Forest.............................. 80 0.02
Mixed Forest.................................. 24 0.01
Shrub......................................... 891 0.19
Grassland/Herbaceous.......................... 194,924 42.49
Pasture/Hay................................... 68,676 14.97
Cultivated Crops.............................. 174,620 38.07
Woody Wetlands................................ 3,304 0.72
Emergent Herbaceous Wetlands.................. 361 0.08
-------------------------
Total................................... 458,741 100.00
------------------------------------------------------------------------
TABLE A-18.--LAND USE DISTRIBUTION OF THE LOWER CANNONBALL RIVER
WATERSHED (HUC 10130206)
------------------------------------------------------------------------
NLCD Land Use Type Hectare Percent
------------------------------------------------------------------------
Open Water.................................... 1,125 0.49
Developed, Open Space......................... 3,709 1.60
Developed, Low Intensity...................... 90 0.04
Developed, Medium Intensity................... 8 ...........
Developed, High Intensity..................... ........... ...........
Barren Land (Rock/Sand/Clay).................. 240 0.10
Deciduous Forest.............................. 1,362 0.59
Evergreen Forest.............................. 42 0.02
Mixed Forest.................................. 23 0.01
Shrub......................................... 265 0.11
Grassland/Herbaceous.......................... 178,363 77.01
Pasture/Hay................................... 8,062 3.48
Cultivated Crops.............................. 35,417 15.29
Woody Wetlands................................ 2,186 0.94
Emergent Herbaceous Wetlands.................. 707 0.31
-------------------------
Total................................... 231,600 100.00
------------------------------------------------------------------------
exhibit b
Figure B-1 through B-7: Time Series of TSS and Flow at USGS
Monitoring Stations at Boundary Stations and within the Missouri River
in North Dakota.
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure B-1.--TSS and Flow Measurements at USGS 06185500, Missouri River
(Culbertson, MT)
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure B-2.--TSS and Flow Measurements at USGS 06342500, Missouri River
(Bismarck, ND)
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure B-3.--TSS and Flow Meas. at USGS 06329500, Yellowstone River
(Sidney, MT), 1965-1980
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure B-4.--TSS and Flow Meas. at USGS 06329500, Yellowstone River
(Sidney, MT), 1980-1995
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure B-5.--TSS and Flow Measurements at USGS 06329500, Yellowstone
River (Sidney, MT),1995-2008
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure B-6.--TSS and Flow Measurements at USGS 06340500, Knife River
(at Hazen, ND)
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure B-7.--TSS and Flow Measurements at USGS 0634900, Heart River
(near Mandan, ND)
appendix b--economic impact of sedimentation and erosion along the
missouri river, north dakota
1.0 INTRODUCTION
The Louis Berger Group Inc. (Berger) was tasked by the U.S. Army
Corps of Engineers (USACE) to assess impacts of sedimentation in the
Missouri River Basin within the State of North Dakota. This assessment
is intended to meet the level of effort defined in the Missouri River
Protection and Improvement Act. The assessment has two objectives.
First, Berger identified sources and deposit locations of sediment
within the Missouri River Basin in the State of North Dakota, utilizing
existing data and information. This task was completed in August
(2008). Next, the team analyzed the potential impacts of sedimentation,
using the results of Task 5A on important issues and resources
including:
--Federal, tribal, State and Regional Economies;
--Recreation;
--Hydropower Generation;
--Fish and Wildlife;
--Flood Control; and
--Indian and Non-Indian Historical and Cultural sites.
Under this subtask the direct economic impacts associated with
increased sedimentation and erosion along the Missouri River in the
State of North Dakota were evaluated. The evaluation includes a
qualitative discussion on whether or not the direct economic impacts
are relevant in scale and location to Federal, tribal, State, and
Regional economies. For instance, certain impacts may be very relevant
to tribal or regional economies due to the location of impacts but may
not be relevant at the State or national levels due to the size of the
impact. Where possible, these distinctions will be made with direct
economic impacts identified in this report.
Berger utilized an integrated approach to evaluate the economic
impacts using the results of other tasks that evaluated the resources
listed above. As such, results of other subtasks were important to the
economic evaluation such as flood control, recreation, and
hydroelectric generation. Thus the task leads worked closely together
to properly identify and quantify, where possible, the potential
impacts in a way that can be used to evaluate economic implications.
Louis Berger has identified potential impacts from erosion and
sedimentation that may have economic impacts to Federal, tribal, State
and Regional economies. These potential impacts were identified in the
results of other subtasks as well as additional literature searches and
interviews with subject matter experts. The potential impacts would be
associated with the following resources or activities including:
--Land Use
--Coal-Fired Power Production
--Hydropower Production
--Recreation
--Water Supply Intakes
Each of these potential impacts is discussed below.
2.0 LAND USE
The initial assumption used for this analysis is that local land
use near or adjacent to the Missouri River can be impacted by fluvial
geomorphic changes, including rapid aggregation and erosion of riparian
lands, and that these changes would lead to complications for
landowners. The evaluations to date show that land uses most likely to
be impacted by erosion and sedimentation include agricultural uses
(grasslands and pasture, cultivated crops) and small areas of
development. The developed areas are near the cities of Williston and
Bismarck.
2.1 Agriculture
To evaluate sedimentation impacts to agricultural lands, Berger
first evaluated the land uses within the aggradation areas identified
in Task 5A. The GIS layers for the aggradation areas were over laid on
agricultural acreage published by the U.S. Department of
Agriculture.\1\ The land use categories were sorted to include only
those uses that were thought to be in agriculture production. Thus,
areas identified as ``wetlands'' were removed from the analysis. The
results provided a summary of potential agricultural land uses that may
be impacted by sedimentation along the Missouri River. Table 2-1
summarizes the acreage by county and level of impact and shows that in
total approximated 43,000 agricultural acres fall within the
aggradations areas. This total distribution of acreage includes 37
percent in low impact areas (16,000), 59 percent in medium impact areas
(25,600) and 4 percent (1,600) in high impact areas.
---------------------------------------------------------------------------
\1\ USDA National Agricultural Statistics Service (NASS) Cropland
Data Layer for Midwestern/Prairie States, 2007.
TABLE 2-1.--ESTIMATED AGRICULTURAL ACREAGE WITHIN THE AGGRADATION AREAS ALONG THE MISSOURI RIVER IN NORTH DAKOTA
----------------------------------------------------------------------------------------------------------------
Level of Impact
County --------------------------------------- Total
Low Medium High
----------------------------------------------------------------------------------------------------------------
Williams.................................................... 3,560 11,947 211 15,717
McKenzie.................................................... 3,162 1,066 182 4,411
Mountrail................................................... 902 294 ........... 1,196
Dunn........................................................ 6 ........... ........... 6
Oliver...................................................... ........... 7,172 ........... 7,172
Morton...................................................... 376 663 508 1,547
Sioux....................................................... 5,539 1,020 ........... 6,558
McLean...................................................... 73 264 ........... 337
Burleigh.................................................... 373 751 717 1,841
Emmons...................................................... 2,135 2,420 ........... 4,555
---------------------------------------------------
Total................................................. 16,126 25,596 1,618 43,339
----------------------------------------------------------------------------------------------------------------
Table 2-2 through Table 2-11 shows a further breakdown of
agricultural land use types impacted within each county.
TABLE 2-2.--AGRICULTURAL LAND USES WITHIN THE AGGRADATION AREAS--WILLIAMS COUNTY
----------------------------------------------------------------------------------------------------------------
Level of Impact Area
Crop Type --------------------------------------- Total
Low Medium High
----------------------------------------------------------------------------------------------------------------
Alfalfa..................................................... 680 331 5 1,016
Barley...................................................... 128 976 ........... 1,104
Canola...................................................... 4 58 1 62
Corn........................................................ 8 757 ........... 764
Clover/Wildflowers.......................................... 1 2 ........... 3
Durum Wheat................................................. 74 1,609 5 1,688
Fallow/Idle Cropland........................................ 32 255 1 288
Flaxseed.................................................... ........... 30 ........... 30
Herbaceous Grassland........................................ 2,301 4,831 190 7,322
Lentils..................................................... 1 561 4 566
Misc. Vegs. And Fruits...................................... ........... 7 ........... 7
Oats........................................................ 4 13 1 18
Peas........................................................ 8 475 4 486
Potatoes.................................................... ........... 215 ........... 215
Safflower................................................... 3 3 1 7
Soybeans.................................................... ........... 6 ........... 6
Spring Wheat................................................ 124 1,187 1 1,311
Sugar beets................................................. 164 406 ........... 570
Sunflowers.................................................. 2 152 ........... 153
Winter Wheat................................................ 26 73 ........... 100
---------------------------------------------------
Total................................................. 3,560 11,947 211 15,717
----------------------------------------------------------------------------------------------------------------
TABLE 2-3.--AGRICULTURAL LAND USES WITHIN THE AGGRADATION AREAS--MCKENZIE COUNTY
----------------------------------------------------------------------------------------------------------------
Level of Impact
Crop Type --------------------------------------- Total
Low Medium High
----------------------------------------------------------------------------------------------------------------
Alfalfa..................................................... 335 2 ........... 337
Barley...................................................... 25 4 1 29
Canola...................................................... 7 2 ........... 9
Corn........................................................ 11 17 4 32
Clover/Wildflowers.......................................... 2 ........... ........... 2
Dry Beans................................................... ........... 1 ........... 1
Durum Wheat................................................. 84 17 ........... 101
Fallow/Idle Cropland........................................ 102 3 ........... 105
Flaxseed.................................................... 2 1 ........... 2
Herbaceous Grassland........................................ 2,428 993 174 3,595
Lentils..................................................... 2 ........... ........... 2
Millet...................................................... 1 1 ........... 2
Misc. Vegs. And Fruits...................................... 1 ........... ........... 1
Oats........................................................ 6 ........... ........... 6
Peas........................................................ 26 ........... ........... 26
Safflower................................................... 5 1 ........... 6
Sunflowers.................................................. 4 ........... ........... 4
Spring Wheat................................................ 118 20 3 141
Sugar beets................................................. 2 3 ........... 4
Winter Wheat................................................ 2 2 1 5
---------------------------------------------------
Total................................................. 3,162 1,066 182 4,411
----------------------------------------------------------------------------------------------------------------
TABLE 2-4.--AGRICULTURAL LAND USES WITHIN THE AGGRADATION AREAS--MOUNTRAIL COUNTY
----------------------------------------------------------------------------------------------------------------
Level of Impact
Crop Type --------------------------------------- Total
Low Medium High
----------------------------------------------------------------------------------------------------------------
Barley...................................................... 17 ........... ........... 17
Canola...................................................... 1 1 ........... 3
Durum Wheat................................................. 10 ........... ........... 10
Fallow/Idle Cropland........................................ 1 ........... ........... 1
Herbaceous Grassland........................................ 772 290 ........... 1,062
Flaxseed.................................................... 1 ........... ........... 1
Oats........................................................ 1 ........... ........... 1
Peas........................................................ 5 1 ........... 6
Spring Wheat................................................ 14 1 ........... 15
Sunflowers.................................................. 1 ........... ........... 1
Winter Wheat................................................ 81 ........... ........... 81
---------------------------------------------------
Total................................................. 902 294 ........... 1,196
----------------------------------------------------------------------------------------------------------------
TABLE 2-5.--AGRICULTURAL LAND USES WITHIN THE AGGRADATION AREAS--DUNN COUNTY
----------------------------------------------------------------------------------------------------------------
Level of Impact
Crop Type --------------------------------------- Total
Low Medium High
----------------------------------------------------------------------------------------------------------------
Herbaceous Grassland........................................ 6 ........... ........... 6
---------------------------------------------------
Total................................................. 6 ........... ........... 6
----------------------------------------------------------------------------------------------------------------
TABLE 2-6.--AGRICULTURAL LAND WITHIN THE AGGRADATION AREAS--MCLEAN COUNTY
----------------------------------------------------------------------------------------------------------------
Level of Impact
Crop Type --------------------------------------- Total
Low Medium High
----------------------------------------------------------------------------------------------------------------
Alfalfa..................................................... ........... 9 ........... 9
Barley...................................................... 1 1 ........... 2
Canola...................................................... ........... 1 ........... 1
Corn........................................................ ........... 7 ........... 7
Dry Beans................................................... ........... 21 ........... 21
Durum Wheat................................................. ........... 1 ........... 1
Herbaceous Grassland........................................ 71 220 ........... 291
Other Small Grains.......................................... ........... 2 ........... 2
Safflower................................................... ........... 1 ........... 1
Spring Wheat................................................ 1 2 ........... 4
---------------------------------------------------
Total................................................. 73 264 ........... 337
----------------------------------------------------------------------------------------------------------------
TABLE 2-7.--AGRICULTURAL LAND WITHIN THE AGGRADATION AREAS--OLIVER COUNTY
----------------------------------------------------------------------------------------------------------------
Level of Impact
Crop Type --------------------------------------- Total
Low Medium High
----------------------------------------------------------------------------------------------------------------
Alfalfa..................................................... ........... 444 ........... 444
Barley...................................................... ........... 73 ........... 73
Canola...................................................... ........... 23 ........... 23
Corn........................................................ ........... 2,141 ........... 2,141
Dry Beans................................................... ........... 61 ........... 61
Durum Wheat................................................. ........... 16 ........... 16
Fallow/Idle Cropland........................................ ........... 11 ........... 11
Flaxseed.................................................... ........... 32 ........... 32
Herbaceous Grassland........................................ ........... 2,450 ........... 2,450
Millet...................................................... ........... 1 ........... 1
Oats........................................................ ........... 19 ........... 19
Peas........................................................ ........... 33 ........... 33
Safflower................................................... ........... 1 ........... 1
Sorghum..................................................... ........... 4 ........... 4
Soybeans.................................................... ........... 19 ........... 19
Spring Wheat................................................ ........... 1,644 ........... 1,644
Sugar beets................................................. ........... 1 ........... 1
Sunflowers.................................................. ........... 196 ........... 196
Winter Wheat................................................ ........... 3 ........... 3
---------------------------------------------------
Total................................................. ........... 7,172 ........... 7,172
----------------------------------------------------------------------------------------------------------------
TABLE 2-8.--AGRICULTURAL LAND USES WITHIN THE AGGRADATION AREAS--MORTON COUNTY
----------------------------------------------------------------------------------------------------------------
Level of Impact
Crop Type --------------------------------------- Total
Low Medium High
----------------------------------------------------------------------------------------------------------------
Alfalfa..................................................... 15 26 31 73
Barley...................................................... 1 2 27 31
Corn........................................................ 26 8 45 80
Fallow/Idle Cropland........................................ 6 ........... 1 7
Herbaceous Grassland........................................ 312 617 355 1,284
Oats........................................................ ........... ........... 1 1
Spring Wheat................................................ 12 8 12 32
Sunflowers.................................................. 4 ........... 2 5
Winter Wheat................................................ ........... ........... 34 34
---------------------------------------------------
Total................................................. 376 663 508 1,547
----------------------------------------------------------------------------------------------------------------
TABLE 2-9.--AGRICULTURAL LAND USES WITHIN THE AGGRADATION AREAS--BURLEIGH COUNTY
----------------------------------------------------------------------------------------------------------------
Level of Impact
Crop Type --------------------------------------- Total
Low Medium High
----------------------------------------------------------------------------------------------------------------
Alfalfa..................................................... 2 2 2 6
Barley...................................................... 2 3 1 5
Canola...................................................... ........... ........... 1 1
Corn........................................................ ........... 4 4 8
Dry Beans................................................... ........... ........... ........... ...........
Fallow/Idle Cropland........................................ ........... ........... 3 3
Herbaceous Grassland........................................ 369 671 694 1,735
Oats........................................................ ........... 5 ........... 5
Peas........................................................ ........... 1 2 2
Soybeans.................................................... ........... ........... ........... ...........
Spring Wheat................................................ ........... 64 11 75
Winter Wheat................................................ ........... 1 ........... 1
---------------------------------------------------
Total................................................. 373 751 717 1,841
----------------------------------------------------------------------------------------------------------------
TABLE 2-10.--AGRICULTURAL LAND USES WITHIN THE AGGRADATION AREAS--EMMONS COUNTY
----------------------------------------------------------------------------------------------------------------
Level of Impact
Crop Type --------------------------------------- Total
Low Medium High
----------------------------------------------------------------------------------------------------------------
Alfalfa..................................................... 7 1 ........... 8
Barley...................................................... 7 3 ........... 10
Canola...................................................... 1 1 ........... 2
Corn........................................................ 8 ........... ........... 8
Dry Beans................................................... 5 ........... ........... 5
Fallow/Idle Cropland........................................ 5 5 ........... 10
Herbaceous Grassland........................................ 2,013 2,377 ........... 4,390
Oats........................................................ 1 2 ........... 2
Potatoes.................................................... 27 ........... ........... 27
Soybeans.................................................... 1 ........... ........... 1
Spring Wheat................................................ 48 23 ........... 71
Sunflowers.................................................. 12 ........... ........... 12
Winter Wheat................................................ 1 8 ........... 9
---------------------------------------------------
Total................................................. 2,135 2,420 ........... 4,555
----------------------------------------------------------------------------------------------------------------
TABLE 2-11.--AGRICULTURAL LAND USES WITHIN THE AGGRADATION AREAS--SIOUX COUNTY
----------------------------------------------------------------------------------------------------------------
Level of Impact
Crop Type --------------------------------------- Total
Low Medium High
----------------------------------------------------------------------------------------------------------------
Alfalfa..................................................... 177 87 ........... 264
Barley...................................................... 57 26 ........... 83
Canola...................................................... 2 4 ........... 6
Corn........................................................ 721 6 ........... 727
Durum Wheat................................................. ........... ........... ........... ...........
Fallow/Idle Cropland........................................ 7 ........... ........... 7
Flaxseed.................................................... 1 ........... ........... 1
Herbaceous Grassland........................................ 4,234 853 ........... 5,087
Millet...................................................... ........... 1 ........... 1
Oats........................................................ 49 ........... ........... 49
Peas........................................................ ........... 1 ........... 1
Soybeans.................................................... 4 3 ........... 7
Spring Wheat................................................ 223 29 ........... 252
Sunflowers.................................................. 43 10 ........... 54
Winter Wheat................................................ 20 ........... ........... 20
---------------------------------------------------
Total................................................. 5,539 1,020 ........... 6,558
----------------------------------------------------------------------------------------------------------------
While the total acreage within each impact magnitude category and
land use was identified, it is uncertain how these different areas
would be impacted by sedimentation on an annual basis. For instance, it
is possible that acreage within a low impact area would only be
impacted during an extreme flood event. It is likely that acreage
within medium and high impact areas would be impacted more often than
acreage in low impact areas. Because of this uncertainty, it is
impossible to estimate the economic impact on agricultural production
from sedimentation. However, data was collected on the productivity,
prices and returns by land use to gain an understanding of the
importance of these areas to Federal, tribal, State and regional
agricultural industries and economies.
To estimate average economic returns from acreage within
sedimentation impact areas, certain assumptions were needed regarding
agricultural operations. For instance, herbaceous grasslands were
assumed to be used for cattle operations (e.g. cow/calf). Cultivated
crop production was assumed to follow the lands uses identified in the
GIS layer. Berger then collected average productivity, crop and
livestock prices, and average returns on labor and management from the
National Agricultural Statistical Agency and the North Dakota
Agricultural Extension Agency.\2\ These values were used in combination
with acreage estimates to estimate annual revenues and returns.
---------------------------------------------------------------------------
\2\ Where possible, 2009 Projected Crop Budgets published by the
North Dakota Extension Agency were used to estimate average revenue per
acre and returns per acre. For crops that did not have a projected
budget (e.g. sugar beets, potatoes) data on average productivity and
prices were obtained for the National Agricultural Statistical Service
for North Dakota.
---------------------------------------------------------------------------
Table 2-12 shows the estimates of average total annual revenue and
returns for acreage within each county that may be impacted by
sedimentation. For all 43,300 acres, average annual revenue was
estimated to be $13.5 million and annual returns were estimated to
$970,000.
TABLE 2-12.--ESTIMATED ANNUAL REVENUES AND RETURNS TO AREAS POTENTIALLY IMPACTED BY SEDIMENTATION
----------------------------------------------------------------------------------------------------------------
Total Impacted
County Acreage Total Revenue Total Returns
----------------------------------------------------------------------------------------------------------------
Williams........................................................ 15,717 $5,071,164 $501,793
McKenzie........................................................ 4,411 1,358,325 132,906
Mountrail....................................................... 1,196 395,671 25,236
Dunn............................................................ 6 2,018 ( \1\ )
Oliver.......................................................... 7,172 1,724,668 112,531
Morton.......................................................... 1,547 493,904 3,546
Sioux........................................................... 6,558 2,080,086 98,887
McLean.......................................................... 337 113,187 1,736
Burleigh........................................................ 1,841 626,123 -77
Emmons.......................................................... 4,555 1,609,779 102,561
-----------------------------------------------
Total..................................................... 43,339 13,474,924 979,119
----------------------------------------------------------------------------------------------------------------
\1\ NA.
According to the U.S. Bureau of Economic Analysis, value added
produced by Agriculture, Forestry, Fishing and Hunting in 2007 was $2.1
billion for North Dakota. Comparing the estimated revenue from the
potential impacted areas with the value added for the entire State from
these industries, indicates the areas are a relatively small
contributor to the industry and the State economy (less than 1 percent)
as a whole. However, if increased sedimentation were to cause these
areas to be removed from production, it would likely have a measurable
impact on local communities, tribes and counties. This is especially
true for counties with the large percentage of potentially impacted
acreage (Williams, Sioux, Oliver and Emmons).
It is noted here that the impacts discussed above are not related
to lands already part of the flowage easements that have been purchased
by the USACE. In 1996, Congress passed Public Law 104-303, which
required the Federal Government to purchase flowage and saturation
easements from willing sellers within the Buford-Trenton Irrigation
District located on the headwaters of the Garrison Dam/Lake Sakakawea
project and southwest of Williston, North Dakota. According to the
Garrison Dam/Lake Sakakawea Master Plan, published in December 2007,
acquisition of flowage easements in the Buford-Trenton Irrigation
District is nearly complete. The total flowage easement acreage was
approximately 11,750.\3\ While individual owners were compensated for
these easements, the State of North Dakota, county and local
governments will continue to be impacted by the loss in tax base into
the future due to the Federal acquisition of these easements.
---------------------------------------------------------------------------
\3\ USACE, Omaha District, Garrison Dam/Lake Sakakawea Master Plan
with Integrated Programmatic Environmental Assessment, Missouri River,
North Dakota, Update of Design Memorandum MGR-107D, December 14, 2007.
---------------------------------------------------------------------------
The analysis discussed above was only able to examine areas that
may be impacted by increased sedimentation. There are other
agricultural areas along the river that will also be affected by
erosion. Stream bank erosion results in the permanent loss of flood
plain land, leading to a loss of production for individual land owners.
Louis Berger was unable to quantify the magnitude of this impact at
this time given the availability of information and data.
2.1.1. High Water Tables
Berger has discovered that sedimentation may be impacting
agricultural lands near Williston due higher water tables. These
impacts may be causing additional acreage to go out of production.
While there is antidotal evidence of this impact, no studies were
located which evaluate the issue in detail.
2.1.2. Potential Increased Flooding in Developed Areas
Berger completed an evaluation of the potential impacts of
sedimentation on flood control associated with the Missouri River in
North Dakota. The analysis only included a review of Flood Insurance
Studies (FIS) prepared by the Federal Emergency Management Agency
(FEMA) for the Bismarck, North Dakota area to analyze changes in water
surface elevation and its affects on flooding. At this time, new flood
data has not been generated for significant portion of the Missouri
River. The exception is Williams County near the city of Williston
which is now being developed. Due to the lack of new flood data all
along the Missouri River, the analysis was limited to the areas where
historic and current flood data were available, particularly the areas
surrounding the city of Bismarck.
Sedimentation in the reach between the Garrison Dam and Lake Oahe
has resulted in increased risk of flooding in the downstream reach
between the dam and the headwater of Lake Oahe. Because of this
sediment aggradation, the impact of ice dams on seasonal flooding is
increasing. As a means to counter this impact, careful sequenced water
releases during the winter months are made to decrease the potential
for flooding caused by ice effects. Water releases from the Garrison
Dam are also used to provide flood control during other seasons as
well.
Analysis of floodplain maps for the 1985 and 2005 Flood Insurance
Study (FIS) for the city of Bismarck and parts of Burleigh County
indicated that the area of the 100-year floodplain has increased by
nearly 28.6 percent within Burleigh County (Table 2-13). This may be
attributed to areas with high aggradation and/or the natural morphology
of the river changing and/or restricting the channel's ability to
convey the flow associated with a particular storm event.
TABLE 2-13.--FLOODPLAIN AREA COMPARISON
------------------------------------------------------------------------
Burleigh County Bismarck City Limits
------------------------------------------------------------------------
1985 100-year Floodplain--28 mi\2\........ 1985 100-year Floodplain--
2.7 mi\2\
2005 100-year Floodplain--36 mi\2\........ 2005 100-year Floodplain--
3.6 mi\2\
------------------------------------------------------------------------
mi\2\ = square miles
In urban areas such as Bismarck and Mandan, flood plain development
restricts the Missouri River's ability to accommodate increases flows
during certain storm events (e.g. river channel has no room to widen
without affecting properties). Aggradation in this area of the river
compounds the problem resulting in an increase risk of flooding and the
loss of property. Potential buyouts due to flooding concerns in the
Bismarck-Mandan area are estimated at over $100 million.\4\ The impact
of flooding is estimated to be greatest between RM 1300 and 1316, i.e.,
in downtown Bismarck and Mandan.\5\ Flooding also occurs outside of
urbanized areas, affecting cropland and causing soil erosion.
---------------------------------------------------------------------------
\4\ Remus, John, Personal Communication, November, 2008.
\5\ FEMA. Flood Insurance Study--Burleigh County, North Dakota and
Incorporated Areas. FIS Number 3801 5CV000A. Federal Emergency
Management Agency, July 2005.
---------------------------------------------------------------------------
Property owners whose property now lies within the expanded flood
plain may also be impacted by a decline property values and increased
insurance cost. Homes, businesses, and agricultural land are among the
types of properties most heavily affected by an increase in the 100-
year flood plain.
FEMA manages the National Flood Insurance Program (NFIP) which
insures buildings and structures against flood damage. As a result of
changes in the Flood Insurance Rate Map, all entities requiring a
mortgage for structures on property within the 100-year floodplain will
be required to purchase insurance under the NFIP. Owners of buildings
must purchase insurance against damages to the structure of the
building itself and also against damages to the contents of any floors
below flood level that would be inundated in the event of a 100-year
flood. Owners may purchase a basic level of coverage or increase
coverage for an additional cost. The cost of the insurance is based on
the area of the building (square feet). The insurance rate per square
foot is dependent on the building's characteristics, on the date of
construction of the building, and on the ``flood zone'' that the
building is located in.
There are four different types of buildings covered under NFIP:
--Non-residential
--Single-family dwellings
--Condominiums
--2-4 family dwellings
Each building type has a different flood insurance rate depending
on the zone where it is located as delineated in FEMA's Flood Insurance
Rate Map (FIRM). It appears that areas impacted by the new delineation
will be designated as either in FEMA's Zone B or Zone C.
Table 2-15 summarizes the insurance costs per square foot for
buildings of various types located within FEMA's Zone C. This table is
based on the FEMA's Flood Insurance Manual.\6\ At this time, it is
unknown the exact number, type or square footage of structures that may
be required to purchase flood insurance. However, an evaluation of GIS
data \7\ provided by the city of Bismarck associated with the 1985 and
2005 Flood Insurance Study indicates that the number of structures
within the floodplain has declined (Table 2-14). This indicates that
the number of individuals or entities that would be subject to flood
insurance may have actually declined in this area even with an increase
in the size of the 100-year floodplain.
---------------------------------------------------------------------------
\6\ FEMA. National Flood Insurance Program, Flood Insurance Manual,
May 2008, Revised October 2008. Accessed at http://www.fema.gov/pdf/
nfip/manual200810/cover_102008.pdf.
\7\ The city of Bismarck provided GIS layers showing building foot
prints, the 1985 flood plain and the 2005 flood plain that was used for
this analysis.
TABLE 2-14.--BUILDINGS WITHIN FLOOD PLAIN AREAS IN 1985 AND 2005 IN
BISMARCK
------------------------------------------------------------------------
1985 Flood Plain 2005 Flood Plain
------------------------------------------------------------------------
1341 buildings (86 acres)................. 1332 buildings (78 acres)
------------------------------------------------------------------------
To gain an understanding of how individual property owners may be
impacted by flood insurance, a simple example was developed to
demonstrate the magnitude of flood insurance costs. Assume a single
family unit of 1,500 square feet in size without a basement is located
within the floodplain. Basic coverage would cost $1,170 for building
coverage and $1,800 for contents on an annual basis.
As mentioned earlier, properties within the expanded flood plain
are also likely to realize a decline in property value. At this time,
it is not possible to quantify the potential decline in property values
that may occur under this scenario.
TABLE 2-15.--ANNUAL INSURANCE RATES PER SQUARE FOOT FOR $100 IN COVERAGE FOR BUILDINGS IN ZONE C (BASIC/ADDITIONAL)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Single Family 2-4 Family Other Residential Non-Residential
Occupancy -------------------------------------------------------------------------------------------------------
Building Contents Building Contents Building Contents Building Contents
--------------------------------------------------------------------------------------------------------------------------------------------------------
Building Type:
No Basement/Enclosure....................... .78/.21 1.20/.37 0.78/0.21 ........... 0.74/0.21 ........... 0.74/0.21 ...........
With Basement............................... .89/.30 1.36/.43 0.89/0.30 ........... 0.95/0.30 ........... 0.95/0.30 ...........
With Enclosure.............................. .89/.34 1.36/.49 0.89/0.34 ........... 0.95/0.34 ........... 0.95/0.34 ...........
Manufactured (Mobile) Home.................. .78/.38 1.20/.37 ........... ........... ........... ........... 0.95/0.39 ...........
Contents Location:
Basement & Above............................ ........... ........... ........... 1.53/0.56 ........... 1.53/0.56 ........... 1.58/0.61
Enclosure & Above........................... ........... ........... ........... 1.53/0.65 ........... 1.53/0.65 ........... 1.58/0.73
Lowest Floor Only--Above Ground Level....... ........... ........... ........... 1.20/0.59 ........... 1.20/0.59 ........... 0.97/0.43
Lowest Floor Above Ground Level and Higher ........... ........... ........... 1.20/0.37 ........... 1.20/0.37 ........... 0.97/0.31
Floors.....................................
Above Ground Level--More than One Full Floor ........... ........... ........... 0.35/0.12 ........... 0.35/0.12 ........... 0.22/0.12
Manufactured (Mobile) Home.................. ........... ........... ........... ........... ........... ........... ........... 0.85/0.53
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: FEMA, 2008.
3.0 COAL-FIRED POWER GENERATION FACILITIES
Berger has identified seven coal-fired power generation facilities
in North Dakota that may be impacted by sedimentation or erosion along
the Missouri River. Figure 3-1 shows the location of these facilities
relative to the sediment load map produced in the Sedimentation Report.
Berger completed a series of interviews with managers at some of the
facilities to gain knowledge on the potential impacts to their
operations from sedimentation or erosion. Table 3-1 provides a summary
of the plants, location, generation capacity, operator and a summary of
impacts identified in the interviews.
From these interviews, Berger learned the following regarding
potential impacts. Thermoelectric power plants have two dominate uses
for water to conduct basic operations: steam creation for driving
turbines and water for condensing steam back to water, with the latter
constituting the highest volume of water use. Problems incurred at
facilities with once through cooling \8\ from high sedimentation levels
include degradation and plugging of the tubes and tube sheets in
condensers, degradation of mechanical pumps and decreasing thermal
efficiency. Associated impacts include having to reduce power
production and more frequent maintenance. This can reduce the life span
of mechanical pumps from 10 years to 7 years due to sedimentation
requiring plants to obtain new, more expensive equipment increasing
their costs. Many of those interviewed believe that larger costs are
associated with the loss in capacity to generate electricity. This can
lead to a reduction in revenue in the millions over the lifetime of the
facility. In addition, sediment issues can necessitate additional
maintenance over the life of the plant.
---------------------------------------------------------------------------
\8\ Thermal electric plants may either have a once through or
closed loop cooling system. Once through systems can realize a
reduction in thermal efficiencies from sedimentation. Closed cooling
processes have potential withdrawal impacts as well as higher costs
associated with water treatment.
---------------------------------------------------------------------------
To gain an understanding of the cost of lost energy production from
thermal electric plants due to sedimentation issues, Berger was able to
obtain some actual data from one of the facilities over the course of 8
months. The operator provided data on the reductions in capacity due to
issues related to condensers. Reductions in capacity were due to the
following:
--Debris in the condenser causing a decline in efficiency;
--Large ice dams during the winter months at the intake reducing
inlet flows to the pumps;
--Low river levels; and
--River temperatures (Upper Thermal Discharge limitations).
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 3-1.--Location of Coal Fired Power Plants in North Dakota
TABLE 3-1.--IMPACTS OF SEDIMENTATION AND EROSION TO COAL-FIRED POWER PLANTS NEAR THE MISSOURI RIVER IN NORTH DAKOTA
--------------------------------------------------------------------------------------------------------------------------------------------------------
Issues Related to
Power Plant Location Electric Generation Capacity Operator Sedimentation
--------------------------------------------------------------------------------------------------------------------------------------------------------
Antelope Valley........ Beulah.............. Unit 1: 43 8mw; Unit 2: 438mw........ Basin Electric Power Co-op........... Water withdrawals come from
Sakakawea Reservoir (150
feet deep). No direct
sedimentation impacts.
Higher turbidity in the
reservoir lead to higher
water treatment costs
because of a closed
cooling process is
employed. Potential
sedimentation impacts to
water withdrawals but no
impact to plant
efficiencies.
Coal Creek............. Underwood........... Unit 1: 550mw; Unit 2: 550mw......... Great River Energy Co-op............. Higher turbidity in water
source will cause an
increase in water
treatment costs because of
a closed cooling process
is employed. Potential
sedimentation impacts to
water withdrawals but no
impact to plant
efficiencies.
Leland Olds............ Stanton............. Unit 1: 216mw; Unit 2: 440mw......... Basin Electric Power Co-op........... Missouri River provides
once through cooling. The
performance of the
condensers can be
adversely affected by the
build-up of sediment,
scale, corrosion or
biological growth inside
the tubes. Erosion can
affect mechanical pumps.
etc. Impacts can lead to a
decrease in thermal
efficiency and requires a
reduction in electrical
generation.
Coyote................. Beulah.............. Unit 1: 4 14mw....................... Otter Tail Corp...................... Coyote is not a once
through system; pump to
secondary pond then from
pond to plant. Siltation
affects condensers, pumps
and pipelines that bring
water to the plant.
Sedimentation impacts on
condensers can cause
millions of dollars in
maintenance and
replacement costs. For a
50 year plant, sediment
issues can necessitate
maintenance to occur once
or twice over the 50 year
lifetime. Sediment can
also plug the river intake
itself, which is an issue
at this plant from time to
time. If output from dam
falls below 11,000 cfs,
intakes will silt in.
Milton R. Young........ Center.............. Unit 1: 257mw; Unit 2: 454mw......... Minnkota Power Co-op................. Missouri River is the main
source of surface water.
Water removed from river
is diverted to stand-alone
man-made lake for once
through cooling.
Stanton................ Stanton............. Unit 1: 170mw........................ Great River Energy Co-op............. Missouri River provides
once through cooling.
Heskett Station........ Mandan.............. Unit 1: 25mw; Unit 2: 75mw........... Montana Dakota Utilities Co.......... Missouri River provides
once through cooling.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Berger evaluated the data and selected occurrences that were most
likely tied to increases in sedimentation. The results are summarized
in Figure 3-2. Over the 8 month period, this facility lost over 13,000
MWh in electricity generation due to sedimentation issues. To evaluate
the value of this reduction in capacity, Berger utilized wholesale
electricity rates published by the Energy Information Agency for the
Cinergy Hub during 2008 (EIA, 2008).
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 3-2.--Loss in Capacity (MWh) due to Sedimentation
Weekly weighted average wholesale prices were used to estimate an
average monthly price used in the analysis as summarized in column
three of Table 3-2. The average monthly price was applied to the
decrease in capacity that may be due to increased sedimentation for
this particular facility. It is assumed that this facility would either
experience a reduction in revenue with a decrease in capacity or would
need to purchase electricity from the wholesale market to meet contract
obligations. This would likely either result in a loss in sales or an
increase in cost to the operator. Table 3-2 represents an estimated
value in the loss of this capacity based on the assumptions listed
above over an 8 month period.
TABLE 3-2.--ESTIMATED VALUE OF LOST POWER PRODUCTION CAPACITY DUE TO SEDIMENTATION
----------------------------------------------------------------------------------------------------------------
Wholesale
Month MWh Reduction Price Per MWh Energy Value
----------------------------------------------------------------------------------------------------------------
Jan............................................................. 4,808 $45.17 $217,139
Feb............................................................. 1,207 78.00 94,120
Mar............................................................. .............. 67.67 ..............
Apr............................................................. 274 73.06 20,018
May............................................................. .............. 61.50 ..............
Jun............................................................. 5,333 53.70 286,400
Jul............................................................. 181 93.42 16,862
Aug............................................................. 1,374 64.00 87,931
-----------------------------------------------
Total..................................................... 13,176 .............. 722,470
----------------------------------------------------------------------------------------------------------------
4.0 HYDROPOWER
Hydropower facilities along the Missouri River in North Dakota
consist of the Garrison Dam and its reservoir, Lake Sakakawea. In
addition, hydropower operations in North Dakota are affected by the
operation of Oahe Dam in South Dakota because Lake Oahe extends into
southern North Dakota up to just south of the city of Bismarck when the
pool is full. Louis Berger completed an evaluation of the potential
impacts to hydropower generation at the Garrison facility. The results
indicate the only measurable impact of sedimentation on hydropower
generation at this time is a loss in power production during the colder
months of the year due to increased flooding risks. This section will
evaluate the economic implications of this loss in power production.
Outflows from Lake Sakakawea at Garrison Dam are commonly through
the power facilities. The power facilities have a normal capacity of
38,000 cfs and a maximum capacity of 41,000 cfs.\9\ The average outflow
is 22,800 cfs, resulting in an annual plant factor of approximately 60
percent. The Garrison Dam has a five unit power plant with a generating
capacity 583.3 MW. This reflects a recent upgrade from previously 518
MW (USACE, 2006).
---------------------------------------------------------------------------
\9\ USACE, Northwest Division. Missouri River Mainstem Reservoir
System, Master Water Control Manual, Missouri River Basin. 2006.
---------------------------------------------------------------------------
The benefits of the hydropower facilities along the Missouri River
consist of providing dependable energy to meet annual peak power
demands of the region. Energy generated by these facilities have
valuable characteristics that improve the reliability and efficiency of
the electric power supply system, such as efficient peaking, a rapid
rate of unit unloading, and rapid power availability for emergencies in
the power grid (USACE, 2006). Further, the facilities generate clean
energy with a minimal carbon-footprint.
Annual gross power generation at Garrison Dam was on average 2.29
million MWh from 1967 (2 years after Lake Sakakawea was filled) through
2007 (Table 4-1). During this time, the annual power generation at the
dam has ranged from 1.31 million MWh in 2007 to 3.35 million MWh in
1975. Hydropower generation is highest during the winter heating season
(December to mid-February) and in the summer when air-conditioning
systems are used (mid-June to early September).
In general, power generation has decreased over time, largely as a
function of decreased runoff in the watershed caused by drought. The
exception occurred during the mid-1990s when spring snow melt and high
rainfall in the Upper Missouri River watershed resulted in high power
generation rates. In addition, some generation capacity, especially
during the winter months, has been lost and sedimentation is playing an
unquantifiable part.
To get an understanding to the impacts that may occur with a
reduction in hydropower capacity at the Garrison facility during the
winter, an analysis was conducted on average power production as
follows. Water release rates at Garrison Dam for ice-in vary from year
to year depending on the specific conditions and needs of other users.
Under ``normal conditions'', the USACE would release from ``the top of
the maintenance zone'' and gradually release the water over the winter.
However, reduced runoff in the watershed has resulted in a decline in
power generation between 1967 and 2008 by almost a factor of two. Louis
Berger used linear regression to estimate the decline as approximately
8 percent greater during the 5-month-long colder period (December to
April) than during the other months of the year. Although there are
other potential causes for a relatively greater decline during the
winter months (such as the statistical effect of the floods in the mid-
1990s), aggradation in the Missouri River in the headwater of Lake Oahe
have likely contributed to this decline but at an unquantifiable level.
TABLE 4-1.--GROSS ENERGY PRODUCTION IN GARRISON RESERVOIR, JUNE 1967 TO SEPTEMBER 2008 (IN MWH)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
MONTH
YEAR -----------------------------------------------------------------------------------------------------------------------------------------------------------
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1967................................ ........... ........... ........... ........... ........... 232,818 295,092 336,767 237,050 275,633 237,942 241,156
1968................................ 252,539 250,001 172,681 196,858 181,466 149,118 156,431 189,139 212,389 290,561 220,158 234,317
1969................................ 270,694 273,173 274,214 226,709 220,131 163,022 257,475 282,114 238,412 234,153 234,215 270,807
1970................................ 238,768 229,732 184,253 216,135 249,277 249,694 253,971 260,164 202,972 254,324 255,847 226,249
1971................................ 278,471 237,686 261,810 310,917 344,378 316,965 332,812 252,987 219,089 227,357 231,432 227,571
1972................................ 264,805 246,236 251,070 339,180 355,277 337,281 259,622 223,343 193,055 207,270 207,332 216,580
1973................................ 252,601 214,626 235,511 184,710 162,558 175,566 195,675 200,477 182,992 184,094 183,062 216,226
1974................................ 239,337 220,615 229,313 173,132 193,606 216,058 250,441 265,274 217,902 274,602 224,294 229,846
1975................................ 202,670 228,625 228,566 159,040 300,368 344,928 327,106 346,401 344,051 307,207 301,414 259,895
1976................................ 238,366 267,342 241,560 280,298 293,607 337,657 347,855 297,624 241,298 240,857 267,802 222,627
1977................................ 261,495 226,827 187,604 145,158 146,577 140,361 161,710 149,503 130,351 116,836 144,514 188,750
1978................................ 238,901 223,758 170,809 152,426 147,911 282,902 365,976 359,461 297,607 294,386 288,538 216,800
1979................................ 273,286 242,247 243,472 247,986 337,281 326,261 248,273 200,522 161,316 143,923 131,469 185,069
1980................................ 211,978 250,217 244,215 180,241 171,693 187,355 242,163 220,382 195,389 205,592 215,010 192,581
1981................................ 223,298 221,708 201,301 144,434 157,530 220,945 258,497 211,709 169,211 137,018 134,494 174,483
1982................................ 229,612 246,046 230,513 150,534 220,269 205,686 241,775 196,792 165,964 182,936 273,082 214,505
1983................................ 195,282 252,410 265,769 202,091 158,451 166,381 171,991 255,878 213,868 133,385 156,472 209,450
1984................................ 255,688 234,352 177,212 149,491 133,458 133,898 219,728 268,821 241,132 229,359 235,378 208,485
1985................................ 252,369 240,712 177,209 160,436 177,001 188,864 185,625 173,756 156,144 127,688 139,786 199,184
1986................................ 235,321 212,537 229,322 170,761 99,653 141,125 188,609 235,182 184,242 214,922 226,168 193,816
1987................................ 226,673 231,899 158,323 97,604 148,884 169,561 180,083 178,711 154,063 127,735 122,734 191,642
1988................................ 198,547 223,301 175,902 159,051 168,085 166,187 172,799 160,599 117,128 95,739 94,058 159,654
1989................................ 163,976 170,372 137,847 130,908 182,384 192,195 198,356 190,547 108,517 95,189 158,685 170,366
1990................................ 206,707 148,555 128,636 146,336 164,180 168,175 172,163 158,428 92,532 88,832 96,474 148,656
1991................................ 173,156 159,305 103,663 140,304 163,980 161,695 174,731 173,966 118,687 116,791 122,517 166,840
1992................................ 196,593 164,598 108,911 136,972 169,802 164,615 172,671 160,192 115,239 86,884 84,653 156,621
1993................................ 159,708 104,673 89,163 85,072 134,907 138,487 137,753 149,864 104,769 96,345 102,339 130,855
1994................................ 136,453 117,532 115,117 111,526 231,975 216,358 190,774 184,486 150,159 112,592 128,289 180,847
1995................................ 199,766 175,462 134,753 111,981 119,587 105,419 137,043 300,487 347,671 353,293 294,565 197,713
1996................................ 221,226 191,266 182,434 250,196 290,399 335,550 367,096 359,879 331,570 261,562 197,127 185,159
1997................................ 218,714 183,318 153,772 154,629 297,147 360,731 377,870 362,492 359,527 356,377 316,385 199,143
1998................................ 197,614 198,563 173,961 170,373 214,778 223,976 219,973 220,021 185,343 146,834 175,793 190,242
1999................................ 221,959 217,155 212,825 235,541 236,204 265,232 267,076 260,022 210,046 171,329 154,754 177,371
2000................................ 187,146 200,649 163,472 167,992 197,165 209,323 210,979 204,901 151,966 122,592 174,651 153,161
2001................................ 159,385 129,011 113,542 103,331 105,408 116,976 121,032 122,385 94,213 85,351 85,865 111,259
2002................................ 111,452 100,760 99,396 86,132 106,810 172,552 179,593 180,714 144,581 118,357 146,246 162,429
2003................................ 150,925 164,934 142,549 150,091 155,550 174,755 183,761 177,311 135,844 86,510 93,167 130,288
2004................................ 156,136 171,953 132,585 130,906 126,761 140,007 145,470 138,970 116,618 92,022 97,700 119,484
2005................................ 118,210 90,236 93,733 129,719 125,240 115,245 125,521 127,459 110,058 100,814 103,473 122,061
2006................................ 140,181 109,310 114,305 104,814 122,996 158,479 169,765 176,082 135,781 94,534 99,072 117,784
2007................................ 121,942 108,113 112,359 100,052 104,596 125,814 130,747 129,425 90,900 85,512 82,820 117,329
2008................................ 117,115 110,226 97,062 92,767 98,124 110,098 114,729 119,052 104,899 ........... ........... ...........
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
TABLE 4-1 (CONTINUED).--GROSS ENERGY PRODUCTION IN GARRISON RESERVOIR, JUNE 1967 TO SEPTEMBER 2008 (IN MWH)
--------------------------------------------------------------------------------------------------------------------------------------------------------
FULL YEAR (Jan-Dec) Colder Months (Dec-Apr)
Year ------------------------------------------------------------------------------------------
MIN MAX TOTAL MEAN MIN MAX Mean
--------------------------------------------------------------------------------------------------------------------------------------------------------
1967......................................................... 232,818 336,767 ........... ........... 172,681 252,539 222,647
1968......................................................... 149,118 290,561 2,505,658 208,805 226,709 274,214 255,821
1969......................................................... 163,022 282,114 2,945,119 245,427 184,253 270,807 227,939
1970......................................................... 184,253 260,164 2,821,386 235,116 226,249 310,917 263,027
1971......................................................... 219,089 344,378 3,241,475 270,123 227,571 339,180 265,772
1972......................................................... 193,055 355,277 3,101,051 258,421 184,710 252,601 220,806
1973......................................................... 162,558 252,601 2,388,098 199,008 173,132 239,337 215,725
1974......................................................... 173,132 274,602 2,734,420 227,868 159,040 229,846 209,749
1975......................................................... 159,040 346,401 3,350,271 279,189 238,366 280,298 257,492
1976......................................................... 222,627 347,855 3,276,893 273,074 145,158 261,495 208,742
1977......................................................... 116,836 261,495 1,999,686 166,641 152,426 238,901 194,929
1978......................................................... 147,911 365,976 3,039,475 253,290 216,800 273,286 244,758
1979......................................................... 131,469 337,281 2,741,105 228,425 180,241 250,217 214,344
1980......................................................... 171,693 250,217 2,516,816 209,735 144,434 223,298 196,664
1981......................................................... 134,494 258,497 2,254,628 187,886 150,534 246,046 206,238
1982......................................................... 150,534 273,082 2,557,714 213,143 195,282 265,769 226,011
1983......................................................... 133,385 265,769 2,381,428 198,452 149,491 255,688 205,239
1984......................................................... 133,458 268,821 2,487,002 207,250 160,436 252,369 207,842
1985......................................................... 127,688 252,369 2,178,774 181,565 170,761 235,321 209,425
1986......................................................... 99,653 235,321 2,331,658 194,305 97,604 231,899 181,663
1987......................................................... 97,604 231,899 1,987,912 165,659 159,051 223,301 189,689
1988......................................................... 94,058 223,301 1,891,050 157,588 130,908 170,372 152,551
1989......................................................... 95,189 198,356 1,899,342 158,279 128,636 206,707 160,120
1990......................................................... 88,832 206,707 1,719,674 143,306 103,663 173,156 145,017
1991......................................................... 103,663 174,731 1,775,635 147,970 108,911 196,593 154,783
1992......................................................... 84,653 196,593 1,717,751 143,146 85,072 159,708 119,047
1993......................................................... 85,072 159,708 1,433,935 119,495 111,526 136,453 122,297
1994......................................................... 111,526 231,975 1,876,108 156,342 111,981 199,766 160,562
1995......................................................... 105,419 353,293 2,477,740 206,478 182,434 250,196 208,567
1996......................................................... 182,434 367,096 3,173,464 264,455 153,772 218,714 179,118
1997......................................................... 153,772 377,870 3,340,105 278,342 170,373 199,143 187,931
1998......................................................... 146,834 223,976 2,317,471 193,123 190,242 235,541 215,544
1999......................................................... 154,754 267,076 2,629,514 219,126 163,472 200,649 179,326
2000......................................................... 122,592 210,979 2,143,997 178,666 103,331 159,385 131,686
2001......................................................... 85,351 159,385 1,347,758 112,313 86,132 111,452 101,800
2002......................................................... 86,132 180,714 1,609,022 134,085 142,549 164,934 154,186
2003......................................................... 86,510 183,761 1,745,685 145,474 130,288 171,953 144,374
2004......................................................... 92,022 171,953 1,568,612 130,718 90,236 129,719 110,276
2005......................................................... 90,236 129,719 1,361,769 113,481 104,814 140,181 118,134
2006......................................................... 94,534 176,082 1,543,103 128,592 100,052 121,942 112,050
2007......................................................... 82,820 130,747 1,309,609 109,134 92,767 117,329 106,900
2008......................................................... 92,767 119,052 ........... ........... ........... ........... ...........
--------------------------------------------------------------------------------------------------------------------------------------------------------
The value of lost power production was estimated as follows. Table
4-2 shows the monthly average hydropower production during the cold
months during two points in time. This includes 1968 and 1972 after the
dam was operational and 2003 and 2007, the last years that data are
available. The average for the cold months for each of these periods is
shown in the last row of the table and indicates that production has
declined by nearly 50 percent.
TABLE 4-2.--MONTHLY MEAN HYDROPOWER PRODUCTION FROM THE GARRISON DAM
----------------------------------------------------------------------------------------------------------------
Cold Month (Dec.-April) Mean Hydropower
Production
Year -----------------------------------------------
Mean Monthly Mean Monthly
Production Year Production
----------------------------------------------------------------------------------------------------------------
1968............................................................ 225,821 2003 144,374
1969............................................................ 227,939 2004 110,276
1970............................................................ 263,027 2005 118,134
1971............................................................ 265,772 2006 112,050
1972............................................................ 184,710 2007 106,900
5-yr Average (MWh).............................................. 233,454 .............. 118,347
----------------------------------------------------------------------------------------------------------------
Table 4-3 shows the reduction in mean power production between the
two time periods. These differences were extrapolated to calculate a
loss in power production over the 5 month cold period as shown in
column 3. In other words, on average power production has declined be
over 570,000 MWh during the cold months between the late 1960s and the
present.
TABLE 4-3.--DIFFERENCE IN HYDROPOWER PRODUCTION
------------------------------------------------------------------------
Mean Cold Total Average
Month Production
Generation During Cold
(MWh) Months (MWh)
------------------------------------------------------------------------
1968-1972............................... 233,454 1,167,269
2003-2007............................... 118,347 591,734
-------------------------------
Difference........................ 115,107 575,535
------------------------------------------------------------------------
Because it is uncertain how much aggradation in downstream reaches
is contributing to flooding and reduced flows from the Garrison Dam
during colder months, several scenarios were developed to provide some
insight on the potential economic impacts to hydropower production. The
results are shown in Table 4-4. The top of the table shows electricity
generation reduction scenarios which range from 10 to 100 percent.
As mentioned earlier, Western markets and transmits the power
generated at the dam at cost to non-profit preference power entities.
While the cost of hydropower production does not change over the year,
the value of the power produced varies due to changes in demand with
the highest demand occurring in the summer and winter. Therefore, the
impacts of a reduction in electricity generation would not occur to
Western but to its customers if it is unable to meet power demands.
This issue has been raised most recently in relation to Western's
inability to meet power commitments due to drought conditions. For
instance, between 2004 and 2007, rates to wholesale customers increased
by 37.3 percent to cover cost of power purchased off the open market
due, in part, to reduced reservoir levels.\10\
---------------------------------------------------------------------------
\10\ ``The Missouri River: A View from Upstream'', Prairie Fire
Newspaper, December 2007, http://www.prairiefirenewspaper.com/print/
178.
---------------------------------------------------------------------------
To value of the loss in electricity generation at the Garrison Dam,
a price differential was applied to the capacity losses as discussion
above. The price differential represents the difference in cost of
production to Western and the average weighted monthly wholesale prices
for winter months discussed in Section 3.0. The difference thus
represents a higher cost alternative for power reduction than
hydropower.
The results are summarized in Table 4-4. Under a low impact
scenario, electricity generation capacity would decline by 10 percent
or 57,000 MWh. Assuming a price differential of $27/MWh, the cost to
replace this capacity with an alternative is $1.5 million per year.
Under a high impact scenario, with the greatest reduction in hydropower
capacity due to various factors and the highest price differential,
losses could reach as much as $34.5 million per year.
TABLE 4-4.--ESTIMATED VALUE OF POWER PRODUCTION SCENARIOS
----------------------------------------------------------------------------------------------------------------
Percentage Reduction in Hydropower (MWh)
----------------------------------------------------------------
10 percent 25 percent 50 percent 75 percent 100 percent
(57,554) (143,884) (287,768) (431,651) (575,535)
----------------------------------------------------------------------------------------------------------------
Value of Lost Production (Sales)--$27/MWh...... $1,553,945 $3,884,861 $7,769,723 $11,654,584 $15,539,445
Value of Lost Production (Sales)--$42/MWh...... 2,417,247 6,043,118 12,086,235 18,129,353 24,172,470
Value of Loss Production (Sales)--$60/MWh...... 3,453,210 8,633,025 17,266,050 25,899,075 34,532,100
----------------------------------------------------------------------------------------------------------------
5.0 RECREATION
Water based recreation, especially sport fishing, has a very
important role in North Dakota's economy. A recent study by North
Dakota State University estimated that the total gross business volume
generated by fishing on Lake Sakakawea alone was as high as $89 million
per year. Thus, changes in the reservoirs or river reaches due to
sedimentation and erosion have potential significant economic
implications. The economic evaluation will utilize the results of
subtask 5C which evaluated the impacts of siltation on recreation in
North Dakota.
Under Task 5A, Berger identified areas of the river impacted most
by the accumulation of sediments and occur approximately 10 to 15 miles
downstream from the upstream end of the lake zones (Lake Sakakawea and
Lake Oahe) created by the Garrison and Oahe Dams. Most of the sediment
accumulation is concentrated within a 30-mile reach of these points.
Under Task 5C, Berger identified recreational sites that are located
within the areas impacted by sedimentation as summarized in Figure 5-1.
According to the sediment aggradation maps, nearly all of the intensive
use recreation sites on Lake Sakakawea are in areas of low to moderate
sedimentation levels. On Lake Oahe, Graner Park Recreation Area and
Kimball Bottom Recreation Area are areas of intense recreational use
that are affected by high levels of sedimentation. MacLean Bottom
Recreation Area is also identified as an area with high sedimentation
levels but the site is considered a low density recreation area. In
all, 1.1 million visitors recreated at sites within areas identified as
either ``low'' or ``moderate'' areas of sediment aggradation on Lake
Sakakawea and an additional 2.3 million visitors recreated at similarly
identified sites in Lake Oahe according to the aggradation maps.
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 5-1.--Developed Recreational Sites within Aggradation Areas
Sedimentation can negatively affect recreation resources in two
ways:
--Direct.--Affecting access or pathways within the reservoirs which
impact visitors ability to access or utilize the water,
compromising their safety, or affecting the aesthetic
environment, or
--Indirect.--Affecting physical properties within the reservoirs
which in turn affect aspects of the recreationists overall trip
(e.g., important fish habitat which would affect the
recreational fishery).
Loss of either access or declines in sport fishing would have
negative consequences on recreators coming to the area for these
activities. This can lead to economic impacts but will depend on how
recreators react to changing conditions. For instance, if sedimentation
reduces access to certain boat ramps at the river or reservoirs but
recreators can utilize alternative sites for access the number of
visitor days may or may not decline. Recreators may need to incur
higher costs to recreate in the area due to traveling farther to gain
access to the site. However, this reaction will not have a negative
impact on the regional or State economy though it may have some
negative impacts to local areas where high sedimentation is occurring.
Louis Berger was unable to find any studies that have evaluated how
recreators would change their behaviors in reaction to sedimentation
levels. Thus, it is unknown how sedimentation may cause economic
impacts to the recreation industry.
5.1 Impacts to Boat Ramps
Erosion and transport of silts and sediments into Lakes Sakakawea
and Oahe can result in the aggradation near boat ramps posing problems
to users and rendering them unusable. Dredging the ramps is currently
performed when access is blocked by sediment build up on and around
ramps; however this poses an ongoing maintenance cost to monitor and
remove the sediments to keep ramps open. Complicating the management of
sediment bound boat ramps are the lake levels. Severe drought in the
recent past has resulted in very low lake levels which leaves some
ramps out of the water or the ends of the ramps a long distance from
the parking area. Sediment aggradation and boat ramp closures in areas
with few points of access would cause additional strain as the cost to
remove the sediment may outweigh the benefit of clearing the ramp
resulting in ramp closures. Ramp closures in remote locations around
the study area would force visitors to drive further to launch a boat.
In some areas, building a new ramp nearby is more cost effective than
dredging existing ramps.
The USACE provides high, mid, and low water ramps at many of the
access areas to accommodate changes in reservoir levels which also
provide alternative access during periods when ramps are covered with
sediment. Most recently Fort Stevenson State Park, Government Bay, and
Sanish Bay were locations within the reservoir that required dredging
to provide boater access. The Fort Stevenson West Ramp was closed
because it is entirely silted in and a brand new marina ramp is being
constructed on the northwest side of the bay. Fort Stevens State Park
is approximately 3 miles south of the town of Garrison; however it is
not known if sediment is being loaded into the arm from tributary or
in-reservoir sources. The Government Bay low water ramp was completely
reconstructed within the last year because of siltation problems as the
bay is filling up with silt and there is no longer a good location for
moving the boat ramp. Complicating matters, the ramp cannot be extended
because of a lack of room. In general, USACE's recent solution has been
to move or extend ramps rather than continue to dredge out areas,
because it is less expensive. These areas are within bays or smaller
arms that are subject to local sedimentation processes and were not
identified as areas of aggradation by Berger under Task 5A that focused
on changes in the elevations within the main channel and thalweg.
6.0 WATER SUPPLY AND IRRIGATION INTAKES
Review of documents and studies has revealed that an increase in
sedimentation along the river is impacting water intakes for
municipalities, irrigation, commercial and industrial customers.
According to the Missouri River Master Manual \11\ there are over 500
water intakes along Lake Sakakawea and the Garrison Reach of the
Missouri River in North Dakota. Table 6-1 summarizes the number and
type of intakes by location.
---------------------------------------------------------------------------
\11\ USACE, Missouri River Master Water Control Manual, Final
Environmental Impact Statement, March 2004.
TABLE 6-1.--WATER INTAKE LOCATIONS ALONG THE MISSOURI RIVER IN NORTH DAKOTA
----------------------------------------------------------------------------------------------------------------
Location Power Municipal Industrial Irrigation Domestic Public Total
----------------------------------------------------------------------------------------------------------------
Lake Sakakawea................... 1 10 (5) 6 (1) 44 (10) 228 (63) 11 300 (79)
Garrison Reach................... 6 3 6 77 28 3 123
----------------------------------------------------------------------------------------------------------------
Source.--USACE, Missouri River Master Water Control Manual, Final Environmental Impact Statement, Table 3.10.1,
p. 3-112, March 2004.( ) Denotes intakes on Reservation Lands.
Berger further evaluated potential impacts to water intakes from
sedimentation. Given that 77 percent of total water use in North Dakota
is for power generation, impacts to these facilities are addressed
separately in Section 3.0. In addition, Berger conducted interviews
with the city of Mandan Water Department and the Public Works Director
of the city of Williston to learn about potential impacts to municipal
water intakes from sedimentation. Both entities indicated that they
have been impacted by increased sedimentation. The city of Mandan's
water intake has been impacted by both increases in sedimentation and
vegetation. The city shares the intake with the Tesoro Refinery. Both
parties have spent several thousands of dollars keeping the intake free
of debris. This includes $150,000 to dredge one-half mile of the river
5 years ago and $20,000 to hire a diver to remove silt from the intake
in April 2007. They are expecting that additional maintenance will be
needed in another 2 years.
The city of Williston originally operated three water intakes from
the Missouri River as the city's sole source of water. Two of these
intakes became completely covered with silt and in 2003 the city
received $2.0 million from the EPA to develop an alternative water
line.
The interviewees indicated that Trenton Indian Service Area, which
is controlled by Turtle Mountain, and the Heskett Plant are also
experiencing impacts to intakes due to sedimentation or increased
vegetation. However, Berger was unable to reach any representatives
from these entities to confirm these statements.
In addition to these uses, 121 intakes are used for agricultural
irrigation which helps to increase crop yields or grow crops that could
not be grown in this region. Most of these irrigation intakes are
portable and placed to access water at a low cost. However, operators
may be impacted by higher operating costs, loss in efficiency or
increases in maintenance related to sedimentation issues.
To get an understanding of how many irrigation intakes may be
affected by sedimentation along the Missouri River in North Dakota,
Berger obtained location data of all the irrigation intakes from the
USACE and plotted these locations on the aggradation maps created under
Task 5A. Each intake located within one-half mile of the aggradation
areas was identified as being potentially impacted by sedimentation.
The analysis showed that 100 intakes were located within defined
aggradation areas. Of these 100 intakes, most were located in either
``low'' or medium aggradation areas while five were located in a
``high'' aggradation area (Table 6-2). It is not known at this time how
intakes within the different aggradation areas may be impacted by
sedimentation though it is likely that operators in areas of high
aggradation will be impacted more severally than those in moderate or
low areas.
TABLE 6-2.--INTAKES WITHIN INDENTIFIED AREAS OF AGGRADATION
------------------------------------------------------------------------
Number of
Level of Aggradation Intakes
------------------------------------------------------------------------
Low..................................................... 48
Moderate................................................ 47
High.................................................... 5
------------------------------------------------------------------------
7.0 CONCLUSIONS
Under this Task, Berger evaluated the potential impacts to
different resources and activities from sedimentation and what
consequences these impacts would have to Federal, tribal, State,
regional economies. It appears that the most significant impact is from
increased flooding in and around Bismarck and Mandan especially in the
winter. Other resources and activities are also experiencing impacts
such as electric power production (hydro and thermal), recreation,
water supply and land use. However none of these impacts appear as
significant as flood control. The report was unable to quantify impacts
to recreation and agricultural use and would suggest these resources be
studied further. In addition, data and costs may become available
associated with operational and maintenance impacts for infrastructure
impacted by sedimentation.
The results of the analysis are summarized in Table 7-1.
TABLE 7-1.--POTENTIAL ECONOMIC IMPACTS OF SEDIMENTATION ALONG THE MISSOURI RIVER IN NORTH DAKOTA
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact to Economy
Resource Potential Impact --------------------------------------- Timeframe Comments
Federal State Local Tribal
--------------------------------------------------------------------------------------------------------------------------------------------------------
Agricultural Land Use............... Loss of Productivity of ....... ........ X X Short Term............ ........................
Ag Lands.
Flood Control....................... Increased Flooding....... ....... X X ........ Long-term............. Increased flooding
potential can lead to
costly buy outs,
increased insurance
costs and reduction in
property values.
Coal-Fired Power Plants............. Reduction in generation ....... ........ X ........ Long-term............. Loss in revenue or
capacity. increase in costs to
meet contract demands.
Hydropower.......................... Reduction in generation ....... X X X Long-term............. Increased flooding
capacity. potential can reduce
hydropower production;
especially during
colder months.
Recreation.......................... Increased maintenance ....... X X X Long-term............. Increased cost to dredge
costs for recreational and maintain facilities
facilities. affected by
sedimentation. Impacts
to visitor behavior are
unknown.
Water Supply........................ Increase operation and ....... ........ X X Long-term............. Small number of intakes
maintenance costs. are impacted by
sedimentation causing
an increase in
operation and
maintenance costs.
--------------------------------------------------------------------------------------------------------------------------------------------------------
References
Energy Information Agency, Wholesale Market Data, Cinergy Hub 2008,
accessed at http://www.eia.doe.gov/cneaf/electricity/wholesale/
wholesale.html.
FEMA. September 1985. Flood Insurance Study--City of Bismarck,
North Dakota Burleigh County. Community Number 380149. Federal
Emergency Management Agency.
FEMA. September 1985. Flood Insurance Study--Burleigh County, North
Dakota Unincorporated Areas. Community Number 380017. Federal Emergency
Management Agency.
FEMA. July 2005. Flood Insurance Study--Burleigh County, North
Dakota and Incorporated Areas. FIS Number 38015CV000A. Federal
Emergency Management Agency.
FEMA. National Flood Insurance Program, Flood Insurance Manual, May
2008, Revised October 2008. Accessed at http://www.fema.gov/pdf/nfip/
manual200810/cover_102008.pdf.
Remus, John, Personal Communication, November, 2008.
``The Missouri River: A View from Upstream'', Prairie Fire
Newspaper, December 2007, http://www.prairiefirenewspaper.com/print/
178.
USACE, Missouri River Master Water Control Manual, Final
Environmental Impact Statement, March 2004.
USDA National Agricultural Statistics Service (NASS) Cropland Data
Layer for Midwestern/Prairie States, 2007.
USACE, Omaha District, Garrison Dam/Lake Sakakawea Master Plan with
Integrated Programmatic Environmental Assessment, Missouri River, North
Dakota, Update of Design Memorandum MGR-107D, December 14, 2007.
USACE, Northwest Division. Missouri River Mainstem Reservoir
System, Master Water Control Manual, Missouri River Basin. 2006.
appendix c--impacts of siltation of the missouri river on recreation in
north dakota
1.0 INTRODUCTION
The Missouri River flows for approximately 410 miles through North
Dakota providing a multitude of recreation opportunities for residents
and visitors alike. Lakes Sakakawea and the upper 70 miles of Lake Oahe
supply approximately 430,000 acres of flat water boating opportunities
between these two reservoirs. The study area includes an area of the
Missouri River from the Montana border to the upstream end of Lake
Sakakawea, which can extend past Williston to just south of Bismarck at
full pool, and also approximately 80 miles of riverine conditions from
Garrison Dam to the upstream end of Lake Oahe (Garrison reach). In the
summer, recreational opportunities in the area consist of boating,
fishing, hunting, camping, hiking, horseback riding, wildlife viewing,
swimming, and sunbathing. In the winter, activities such as
snowmobiling and ice fishing are common in this area.
North Dakota contains one dam, Garrison Dam, and its associated
reservoir, Lake Sakakawea. The reservoir known as Lake Oahe, formed by
the Oahe Dam in South Dakota, also extends into North Dakota from the
south. Therefore, from a recreation perspective the Missouri River in
North Dakota may be thought of as having four parts:
--The Williston Reach.--The riverine segment close to the Montana
border, into which the Yellowstone River flows, and which flows
into Lake Sakakawea. This reach can become inundated by Lake
Sakakawea at full pool;
--Lake Sakakawea.--The reservoir formed by Garrison Dam (finished in
1953), whose entire surface is within the State of North
Dakota;
--The Garrison Reach.--The riverine segment from Garrison Dam to the
headwaters of Lake Oahe; and
--Lake Oahe.--The reservoir formed by Oahe Dam in South Dakota
(closed in 1958), and which is in both North Dakota and South
Dakota.
These four separate regions will be used to describe impacts to
recreation from siltation of the Missouri River in North Dakota.
2.0 LITERATURE AND DATA COLLECTION METHODOLOGY
Several types of information were used to meet study objectives,
including (1) interviews with experienced recreation managers and (2) a
review of existing documents. Key recreation personnel were contacted
from the following institutions:
--North Dakota Game and Fish
--North Dakota Park and Recreation Department
--North Dakota Water Commission
--North Dakota State University
--City of Williston
--Bismarck Parks and Recreation District
--Ford Abraham Lincoln State Park
--United States Army Corps of Engineers, Omaha District
A list of recreation issues, sites, and documents were derived from
the interviews and incorporated into the evaluation. In addition,
Federal, State, and local agencies in the recreation resources arena
were contacted for literature detailing recreation opportunities,
policies, planning efforts, use levels, and attitudes related to
recreation on the Missouri River. The following reports, documents, and
Web sites were reviewed for information related to recreation, erosion,
and siltation related to the study objectives:
--Quarterly Drought Reports from the, (USACE--Omaha District, 2008).
--North Dakota State Comprehensive Outdoor Recreation Plan 2008-2012,
(DH Research, the North Dakota Recreation and Parks Association
and the North Dakota Parks and Recreation Department).
--Missouri River Mainstem Reservoir System Master Water Control
Manual Missouri River Basin (Reservoir Control Center, USACE--
Northwestern Division, 2006).
--A Reference Guide to Water in North Dakota (North Dakota Water
Commission, 2005) The Valley Outdoors: Lake Sakakawea in Peril
\1\ (Leier, 2004).
---------------------------------------------------------------------------
\1\ http://www.nodakoutdoors.com/valleyoutdoors5.php.
---------------------------------------------------------------------------
--Minnesota Public Radio, Water Wars: Recreation on the Missouri
River (Gunderson, July 2, 2003).\2\
---------------------------------------------------------------------------
\2\ http://news.minnesota.publicradio.org/features/2003/07/
03_gundersond_riverrecreation/.
---------------------------------------------------------------------------
3.0 RECREATION OPPORTUNITIES
The Missouri River accounts for 80 percent of the total streamflow
in the State (USGS 2008) and also provides significant water based
recreation opportunities. Recreation facilities along the river vary
from game lands, State parks, municipal parks, Native American owned
and operated facilities, and private access, to primitive dispersed
areas. Figure 3-1 shows the location of the 56 formal recreation areas
along the river in the study area, while Table 3-1 contains the names
of the access points on the figure and summarizes the amenities at the
site and the agency/entity responsible for managing the site.
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
(Source: USACE 2008a, as modified by staff)
Figure 3-1.--Developed Recreation Facilities Along the Missouri River
in North Dakota
TABLE 3-1.--AMENITIES AT EACH DEVELOPED RECREATION FACILITY ALONG THE MISSOURI RIVER IN NORTH DAKOTA
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Amenities at Each Recreation Facility
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Location/Manager ID Fishing
Boat Boat Boat Boat Camping Cabin Electric Drinking Showers Restrooms Picnic Picnic Swim Playground Restaurant/ Boat Dump Cleaning
Ramp Dock Rental Storage Rental Hookup Water Shelter Tables Beach Concession Fuel Station Station
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Lake Trenton/WCWRD............ 1 X X ........ ......... X ........ X X X X X X X X X ...... X X
Little Muddy/WCWRD............ 2 X ...... ........ ......... ........ ........ .......... .......... ......... X X X ....... ............ .............. ...... ......... ..........
American Legion Park/American 3 X ...... ........ ......... X ........ X X ......... X X X ....... ............ .............. ...... ......... ..........
Legion.......................
Lewis and Clark State Park/ 4 X X X X X ........ X X X X X X X X X X X X
State of ND..................
White Tail Bay (Lund's 5 X X ........ ......... X X .......... X X X X X ....... ............ X ...... ......... ..........
Landing)/WCWRD...............
Tobacco Gardens/McKenzie Co. 6 X X ........ ......... X X X X X X X X ....... X X X X X
Park Board...................
Little Egypt/WCWRD............ 7 ...... ...... ........ ......... X ........ .......... .......... ......... X X X ....... ............ .............. ...... ......... ..........
Little Beaver Bay/Williams 8 X X ........ ......... X ........ .......... .......... ......... X X X ....... ............ .............. ...... ......... ..........
County Water Resource
District (WCWRD).............
White Earth Bay/Mountrail 9 X X ........ ......... X ........ .......... X X X X X ....... ............ X ...... X X
County Park Board............
Four Bears/Three Affiliated 10 X X ........ ......... X ........ .......... X ......... X X ......... ....... ............ X X X X
Tribes.......................
New Town/New Town Park Board.. 11 X X ........ X X X X X X X X X ....... X X X X X
Reunion Bay (Sanish Bay)/New 12 X X ........ ......... ........ ........ .......... .......... ......... ........... ......... ......... ....... ............ .............. ...... ......... ..........
Town Park Board..............
Skunk Creek/Three Affiliated 13 X ...... ........ ......... X X .......... .......... ......... X ......... ......... ....... ............ .............. ...... ......... ..........
Tribes.......................
Pouch Point/Three Affiliated 14 X X ........ ......... X ........ X X X X X X ....... ............ X ...... ......... ..........
Tribes.......................
Van Hook/Mountrail County Park 15 X X ........ X X X X X X X X X ....... X X X X X
Board........................
Parshall Bay/Mountrail County 16 X X X ......... X X X X X X X X ....... X X X X X
Park Board...................
Deepwater Creek/USACE......... 17 X X ........ ......... X ........ .......... X ......... X X X ....... ............ .............. ...... ......... ..........
McKenzie Bay/Watford City Park 18 X X X X X X X X X X X X ....... X X X X X
Board........................
Charging Eagle/Three 19 X ...... ........ ......... ........ ........ .......... .......... ......... X ......... ......... ....... ............ .............. ...... ......... ..........
Affiliated Tribes............
Little Missouri Bay (now 20 X ...... ........ ......... ........ ........ .......... .......... ......... X ......... ......... ....... ............ .............. ...... ......... ..........
closed)/USACE................
Indian Hills/State of ND & 21 X X X X X X X X X X ......... X ....... ............ X X X X
Three Affiliated Tribes......
Twin Buttes/Three Affiliated 22 ...... ...... ........ ......... X ........ X .......... ......... X X X X ............ .............. ...... ......... ..........
Tribes.......................
Beaver Creek Bay/Zap Park 23 X X ........ ......... X ........ .......... .......... ......... X X X ....... ............ .............. ...... ......... ..........
Board........................
Lake Shore Park (DakotaWaters)/ 24 X X ........ X X X X X X X X X ....... X X X X X
Beulah Park Board............
Beulah Bay/Beulah Park Board.. 25 X X ........ ......... X X X X X X X X ....... ............ .............. ...... X X
Hazen Bay (Walleye Bay)/Hazen 26 X X ........ ......... X X X X X X X X ....... ............ .............. ...... X X
Park Board...................
Douglas Creek/USACE........... 27 X X ........ ......... X ........ .......... X ......... X ......... X ....... ............ .............. ...... ......... ..........
Lake Sakakawea State Park/ 28 X X X X X X X X X X X X X X X X X X
State of ND..................
Ft. Stevenson State Park/State 29 X X X X X X X X X X X X X X X X X X
of ND........................
Sportsmen's Centennial Park/ 30 X X ........ ......... X ........ X X X X X X X X X ...... ......... X
McLean County................
West Totten Trail/McLean 31 X X ........ ......... ........ ........ .......... .......... ......... X ......... ......... ....... ............ .............. ...... ......... ..........
County.......................
East Totten Trail/USACE....... 32 X X ........ ......... X ........ X X ......... X ......... X ....... ............ .............. ...... X X
Wolf Creek/USACE.............. 33 X X ........ ......... X ........ .......... X ......... X X X ....... X .............. ...... X X
Government Bay/USACE.......... 34 X X ........ ......... ........ ........ .......... .......... ......... X ......... ......... ....... ............ .............. ...... ......... X
Riverdale Overlook/USACE...... 35 ...... ...... ........ ......... ........ ........ .......... .......... ......... ........... X X ....... ............ .............. ...... ......... ..........
Spillway Overlook/USACE....... 36 ...... ...... ........ ......... ........ ........ .......... .......... ......... X X X ....... ............ .............. ...... ......... ..........
Tailrace (Missouri River Ramp)/ 37 X X ........ ......... ........ ........ .......... .......... ......... X ......... ......... ....... ............ .............. ...... ......... X
USACE........................
Tailrace West/USACE........... 38 ...... ...... ........ ......... ........ ........ .......... .......... ......... X ......... ......... ....... ............ .............. ...... ......... ..........
Downstream Campground/USACE... 39 ...... ...... ........ ......... X ........ X X X X ......... X ....... X .............. ...... X ..........
Spillway Pond/USACE........... 40 X ...... ........ ......... ........ ........ .......... X ......... X X X X X .............. ...... ......... ..........
General Sibley Park/city of 41 X ...... ........ ......... X ........ X X X X X X ....... X .............. ...... ......... ..........
Bismarck.....................
Sibley Nature Park (Trail)/ 42 ...... ...... ........ ......... ........ ........ .......... .......... ......... ........... ......... ......... ....... ............ .............. ...... ......... ..........
city of Bismarck.............
Little Heart/Morton County.... 43 X ...... ........ ......... X ........ .......... .......... ......... X ......... ......... ....... ............ .............. ...... ......... ..........
Kimball Bottom/Burleigh County 44 X ...... ........ ......... X ........ .......... .......... ......... X ......... ......... ....... ............ .............. ...... ......... ..........
Kimball Bottom ORV/Burleigh 45 ...... ...... ........ ......... ........ ........ .......... .......... ......... ........... ......... ......... ....... ............ .............. ...... ......... ..........
County.......................
Graner Park/Morton County..... 46 X ...... ........ ......... X ........ .......... .......... ......... X ......... X ....... X .............. ...... ......... X
MacLean Bottom/State of ND.... 47 X ...... ........ ......... X ........ .......... .......... ......... X ......... ......... ....... ............ .............. ...... ......... ..........
Fort Rice/Morton County....... 48 X ...... ........ ......... X ........ .......... .......... ......... X ......... X ....... ............ .............. ...... ......... X
Hazelton/USACE................ 49 X ...... ........ ......... X ........ .......... .......... ......... X ......... ......... ....... ............ .............. ...... ......... X
Badger Bay/USACE.............. 50 ...... ...... ........ ......... X ........ .......... .......... ......... X ......... ......... ....... ............ .............. ...... ......... ..........
Walker Bottom/Standing Rock 51 ...... ...... ........ ......... X ........ .......... .......... ......... X ......... ......... ....... ............ .............. ...... ......... ..........
Sioux Tribe..................
Beaver Creek/USACE............ 52 X ...... ........ ......... X ........ X X X X X X X X .............. ...... X X
Fort Yates/Standing Rock Sioux 53 X ...... ........ ......... ........ ........ .......... .......... ......... X ......... ......... ....... ............ .............. ...... ......... ..........
Tribe........................
Cattail Bay/USACE............. 54 X ...... ........ ......... X ........ .......... .......... ......... X ......... ......... ....... ............ .............. ...... ......... X
Langelier Bay/Emmons County... 55 X ...... ........ ......... X ........ .......... .......... ......... X ......... ......... ....... ............ .............. ...... ......... X
State Line/Emmons County...... 56 X ...... ........ ......... ........ ........ .......... .......... ......... ........... ......... ......... ....... ............ .............. ...... ......... ..........
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
(Source: USACE 2005, USACE 2003, as modified by staff.)
In addition to traditional water based opportunities, recreation
and visitors enjoy a number of other cultural and historical sites and
wildlife areas which are located on the river. A list of these sites is
provided in Appendix A.
3.1 Williston Reach
The Missouri River between the Montana border and the upstream end
of Lake Sakakawea is generally referred to as the Williston reach. This
approximately 60 mile section of the Missouri River is not inundated by
a reservoir and the confluence with the Yellowstone River is within
this reach. From a recreational perspective, the Williston reach is
remote and access is limited to two boat ramps; one at the confluence
with the Yellowstone River and the other about 25 miles down river at
the Highway 85 bridge in Williston, North Dakota (not shown on the
map). Boating and angling are common activities within this reach.
3.2 Lake Sakakawea
Lake Sakakawea is the largest reservoir in North Dakota and as such
provides the greatest amount of flat water recreation opportunities in
the State. There are forty formal public access areas adjacent to the
reservoir of which 37 provide boater access (boat ramps). In addition
to the public recreation facilities, access is provided from private
lands, camps, commercial marinas, and other commercial recreational
facilities (e.g., private campgrounds).
Lake Sakakawea is also North Dakota's largest recreational fishery,
followed by Lake Oahe. Popular sport fish at these two reservoirs
include walleye, salmon, northern pike, sauger, white bass, and channel
catfish. Anglers also participate in ice fishing, shoreline fishing,
boat fishing, and dark-house spearing and take advantage of the cold-
water (salmon), cool-water (especially walleye), warm-water and
riverine fishery opportunities (USACE 2007). Some of the boating is
fishery-related; however, other reservoir activities include
motorboating, sailboating, waterskiing, jetskiing, tubing, and wind
surfing. Shoreline day uses and off road vehicle (OHV) use are popular
at the reservoirs; however, high water levels can eliminate the
conditions necessary to participate in these activities.
3.3 Garrison Reach
Aside from the Williston reach, the Garrison reach, is the only
other section of the river in North Dakota that is not inundated by a
reservoir. This approximately 80 mile reach is however controlled by
releases from Garrison Dam. There are 11 boat ramps within this reach
and although river levels do fluctuate, the river is rarely to low to
canoe (USGS, 2008). The river provides water-based recreation including
boating, boating-related activities, and swimming. However, sport
fishing is a primary component of recreation along this section of the
river. Swift currents along the Missouri River between Garrison Dam and
Bismarck are popular with experienced canoeists; while nature lovers
enjoy wildlife viewing for bald and golden eagles, osprey, beaver, and
deer (USACE 2006).
3.4 Lake Oahe
Lake Oahe is the second largest reservoir in North Dakota and as
such recreation is typically water based with boating and fishing the
most popular activities. Recent drought conditions have changed the
upstream reservoir sections from flat water (typically at elevations
above 1,600-1,608 ft msl) to riverine characteristics which could
affect the types of activities occurring within this section of the
study area or leave boat ramps unusable altogether.
4.0 CURRENT RECREATIONAL USE
The USACE monitors recreation use activity throughout the study
area. The amount of estimated use at formal and dispersed sites within
the study area is summarized by general area below.
4.1 Lake Sakakawea
In 2008, the USACE found that recreation use levels, including
dispersed recreation, at Lake Sakakawea consisted of over thirteen
million visitor hours.\3\ Of that total, dispersed recreation is
estimated to account for over 2 million visitor hours on Lake
Sakakawea. According to USACE data, recreation sites that received the
most visitor hours include: Van Hook with over 1 million visitor hours,
game management lands with nearly 1 million visitor hours, Fort
Stevenson State Park accounting for about 950,000 visitor hours, Lake
Sakakawea State Park with approximately 720,000 visitor hours, East
Totten Trail with nearly 700,000 visitor hours, and Lake Shore Park
with over 575,000 visitor hours. Table 4-1 shows USACE visitor use
estimates (actual users) for 40 formal and combined dispersed use areas
around the lake for the years 2005 to 2008.
---------------------------------------------------------------------------
\3\ Visitor hour is defined as the presence of one or more persons
on an area of land or water for the purpose of engaging in one or more
recreation activities during continuous, intermittent, or simultaneous
periods of time aggregating to 60 minutes. Visitor-hour incorporates
both the number of participants and duration of use and provides an
estimate on the ``amount'' of use (USACE (Oahe Master Plan) 2007).
TABLE 4-1.--NUMBER OF RECREATIONAL USER ON LAKE SAKAKAWEA
----------------------------------------------------------------------------------------------------------------
Recreation Site 2005 2006 2007 2008
----------------------------------------------------------------------------------------------------------------
Fort Stevenson State Park....................... 948,435 1,208,383 975,556 952,910
Lake Sakakawea State Park....................... 1,084,604 1,006,966 1,047,370 722,110
Downstream...................................... 895,659 872,760 763,113 995,582
Spillway Overlook............................... 50,711 52,410 51,451 53,272
Wolf Creek...................................... 215,953 225,762 169,548 131,894
East Totten Trail............................... 774,454 789,407 811,685 696,755
Douglas Creek................................... 138,018 158,493 107,236 246,966
Deep Water Creek................................ 205,276 211,304 204,431 139,767
Lewis and Clark State Park...................... 204,023 120,676 127,957 128,222
Tobacco Garden.................................. 215,990 75,669 65,245 108,825
McKenzie Bay.................................... 313,674 364,795 249,653 306,695
Little Missouri \1\............................. .............. .............. .............. ..............
Charging Eagle.................................. 336,151 332,481 304,942 276,837
Beulah Bay...................................... 512,623 540,316 391,570 450,855
Missouri River Ramp............................. 297,261 310,459 310,276 328,106
Riverdale Overlook.............................. 11,870 13,245 9,827 14,665
Parshall Bay.................................... 579,234 618,510 416,201 465,110
Van Hook Area................................... 811,438 1,023,799 1,024,974 1,199,300
New Town........................................ 257,215 279,656 262,736 184,036
Twin Buttes..................................... 28,117 16,857 32,401 16,678
Hazen Bay....................................... 229,406 249,017 302,255 277,534
American Legion Park............................ 33,854 30,622 19,854 71,493
Lake Trenton.................................... 263,887 207,277 230,401 253,550
Little Beaver................................... 8,246 12,195 9,714 14,540
Power Plant..................................... 2,723 1,138 1,823 1,878
Game Management................................. 1,176,316 1,176,715 1,175,256 1,145,243
Sportsmen's Centennial (Benedict)............... 157,194 153,958 115,942 139,123
White Earth Bay................................. 75,431 96,543 107,446 75,389
Beaver Creek.................................... 98,128 143,699 128,816 144,564
Pouch Point Bay................................. 229,132 147,288 103,956 172,127
White Tail Bay.................................. 31,348 37,203 30,460 122,301
Indian Hills.................................... 229,736 227,217 226,759 205,751
West Totten Trail............................... 14,771 18,170 14,441 15,397
Lake Shore Park................................. 562,616 548,735 582,109 576,504
Government Bay.................................. 80,191 77,659 77,187 78,525
Spillway Pond................................... 24,239 15,702 16,171 22,855
Little Muddy.................................... 34,001 27,320 18,883 26,619
Little Egypt.................................... 11,517 13,303 11,777 10,229
West Trail Race................................. 37,594 38,728 34,070 41,480
Reunion Bay..................................... 39,009 42,929 28,667 32,184
Skunk Creek Bay................................. 230,234 230,053 79,931 96,770
Dispersed Use................................... 1,706,500 1,706,092 1,913,077 2,268,823
----------------------------------------------------------------------------------------------------------------
\1\ Drought conditions rendered the site unusable.(Source: USACE, 2008)
Angling is the most popular recreation activity on Lake Sakakawea.
Boating and sightseeing are also popular activities as they are often
occurring within the same party on the same day. Table 4-2 summarizes
the mix of activities and the primary purpose of trips taken by
visitors to Lake Sakakawea.
TABLE 4-2.--RECREATIONAL ACTIVITY MIX AT LAKE SAKAKAWEA
------------------------------------------------------------------------
Percent of All Percent of
Recreation Activity Activities Visits
------------------------------------------------------------------------
Fishing............................... 41.7 23.1
Boating............................... 39.7 22.0
Sightseeing........................... 31.1 17.2
Other (jetskiing, hiking, playground, 22.1 12.2
bird watching, pow-wows etc.)........
Camping............................... 19.5 10.8
Picnicking............................ 11.7 6.5
Swimming.............................. 8.7 4.8
Hunting............................... 3.5 1.9
Waterskiing........................... 2.4 1.3
Winter Activities..................... < 1 < 1
Total Percent2........................ 180.5 100
Activities Per Visit.................. 1.8 ...............
------------------------------------------------------------------------
(Source: USACE 2007, modified by staff)
4.2 Garrison Reach
Visitor use estimates for the Garrison reach are more difficult to
calculate. North Dakota Game and Fish Department (NDGFD) most recent
creel surveys estimated 95,322 angler days during 2007 (NDGFD 2007b)
which amounted to over 338,000 angler hours along this reach. Boat
anglers accounted for over 80 percent of the estimate (NDGFD 2007b).
Overall, visitation is likely much higher when considering the canoe
trips and land based opportunities within the reach.
4.3 Lake Oahe
The USACE estimated recreational use of Lake Oahe sites within
North Dakota totaled approximately 3.8 million visitor hours in 2008
(USACE 2008). Recreation sites that received the most visitor hours
included: General Sibley Park with approximately 1.4 million visitor
hours, Kimball Bottom with over 850,000 visitor hours, Beaver Creek
with over 300,000 visitor hours, Graner Bottom with approximately
280,000 visitor hours, and Hazelton with nearly 272,000 visitor
hours.\4\ Table 4093 shows the USACE visitor use estimates (actual
users) for 15 formal and combined dispersed use areas around the lake
for the years 2005 to 2008.
---------------------------------------------------------------------------
\4\ The total percent of activities is greater than 100 percent
because many people participated in more than one activity at a given
recreation area.
TABLE 4-3.--NUMBER OF RECREATIONAL USERS ON LAKE OAHE
----------------------------------------------------------------------------------------------------------------
Recreation Site 2005 2006 2007 2008
----------------------------------------------------------------------------------------------------------------
Fort Yates...................................... 122,523 96,178 53,727 60,646
Cattail Bay..................................... 85,903 86,504 70,461 76,428
Beaver Creek.................................... 276,485 234,492 277,777 329,614
Badger Bay...................................... 5,538 4,587 3,416 4,670
Hazelton........................................ 104,741 150,906 173,419 271,992
Fort Rice....................................... 24,731 30,908 38,769 43,140
Graner Bottom................................... 235,735 150,473 265,718 280,006
Little Heart (NDG&F Managed).................... 148,686 163,741 168,123 115,290
East Sibley Park (Nature Trail)................. 2,913 3,611 5,378 6,560
General Sibley Park............................. 702,388 995,321 1,343,763 1,439,609
Kimball Bottom.................................. 838,378 656,671 620,293 856,412
Langelier....................................... 5,760 6,044 3,452 13,407
Kimball Bottom ORV.............................. 257,240 214,088 1,999,598 137,449
Maclean Bottom.................................. 134,692 187,071 208,501 146,657
Prairie Knights Marina (Walker Bottom).......... 29,120 29,337 19,758 26,571
----------------------------------------------------------------------------------------------------------------
Note.--This area of Oahe in North Dakota generally consisted of ``river'' conditions rather than ``Lake''
conditions during these years.(Source: USACE, 2008)
Fishing, boating, and sightseeing are the most popular activities
on Lake Oahe. According to the USACE, hunting accounts for 60 to 80
percent of total visitor hours in the fall, but may be misrepresented
because of a lack of traffic counters on hunting related roads. Table
4-4 summarizes activity participation rates for visitors to Lake Oahe.
TABLE 4-4.--ACTIVITY MIX FOR LAKE OAHE
------------------------------------------------------------------------
Activity
Participation
Recreation Activity Rate
(percent)
------------------------------------------------------------------------
Fishing................................................. 43.9
Boating................................................. 30.0
Sightseeing............................................. 22.0
Other................................................... 16.1
Camping................................................. 7.0
Swimming................................................ 5.6
Hunting................................................. 4.9
Picnicking.............................................. 3.6
Waterskiing............................................. 0.6
---------------
Total \1\......................................... 133.7
------------------------------------------------------------------------
\1\ Totals more than 100 percent as users typically participate in more
than one activity.(Source: USACE 2007, modified by staff)
5.0 RECREATIONAL NEEDS
USACE Lake Sakakawea Master Plan (2007) and Lake Oahe Draft Master
Plan (2007) estimate that recreation use levels at both reservoirs are
expected to grow in the coming years causing increasing demand for
recreational facilities throughout the study area. Facility needs were
identified by the North Dakota Parks and Recreation Department (NDPRD)
in the North Dakota 2003-2008 State Comprehensive Outdoor Recreation
Plan (SCORP) through the use of eight public forums (one for each SPR)
that included recreation agency representatives and members of the
general public. The top six recreational priorities of the planning
districts adjacent to the study area were the same as those identified
in the State and included: (1) Trails, (2) golf courses, (3) sports
courts, (4) pools/beaches, (5) playgrounds/picnic areas, and (6) sports
fields. Activities occurring in the study area but not in the top six
were: water access (ranked 7th by adjacent planning districts),
historic sites (ranked 8th by adjacent planning districts), and
campgrounds (ranked 14th by adjacent planning districts). Because the
study area offers the majority of flat water and a substantial amount
of river based recreation opportunities in the State, the recreation
sites within the study area will have to keep up with the demand for
water access.
6.0 EFFECTS OF SILTATION ON RECREATION RESOURCES
Lake Sakakawea receives approximately 1,642 acre-feet of sediment
as estimated at the Montana/North Dakota border (The Louis Berger Group
[Berger], 2008). Sedimentation presents hazards to boaters, impairs
fisheries, creates marshy areas, and jeopardizes recreation facilities
(USACE, 2007). Siltation can negatively affect recreation resources in
two ways:
--Direct.--Affecting access or pathways within the reservoirs
affecting visitors ability to access or utilize the water,
compromising their safety, or affecting the aesthetic
environment, or
--Indirect.--Affecting physical properties within the reservoirs
which in turn affect aspects of the recreationists overall trip
(e.g., important fish habitat which would affect the
recreational fishery).
Loss of either access or declines in sport fish would have negative
consequences on the amount of recreation visits to the study area which
would have negative effects on the local economies that depend on
recreation. Economic effects of sedimentation will be evaluated under a
separate task for this project.
Erosion and transport of silts and sediments into Lakes Sakakawea
and Oahe can result in the aggradation near boat ramps posing problems
to users and rendering them unusable. Dredging the ramps is currently
performed when access is blocked by sediment build up on and around
ramps; however this poses an ongoing maintenance cost to monitor and
remove the sediments to keep ramps open. Complicating the management of
sediment bound boat ramps are the lake levels. Severe drought in the
recent past has resulted in very low lake levels which leaves some
ramps out of the water or the ends of the ramps a long distance from
the parking area. Sediment aggradation and boat ramp closures in areas
with few points of access would cause additional strain as the cost to
remove the sediment may outweigh the benefit of clearing the ramp
resulting in ramp closures. Ramp closures in remote locations around
the study area would force visitors to drive further to launch a boat.
In some areas, building a new ramp nearby is more cost effective than
dredging existing ramps.
In addition to compromising access to the water, siltation can
compromise boater safety by filling in the historic river channel. When
river channels are filled in the resulting shallower reservoir can
cause unsuspecting boaters to hit bottom possibly injuring the boaters
or causing damage to the boat motors.
Sedimentation can also have negative effects on biological
resources. Silt entering the study area settles to the bottom altering
the bottoms of the river and reservoirs potentially negatively
affecting spawning habitat. Walleye are the most sought after fish in
the study area and the area has a productive walleye fishery. Walleye
spawn on gravel and siltation greatly reduces the quantity and quality
of walleye spawning habitat (Garrison Master Plan, 2007).
Over time, sediment accumulations could fill in the deeper areas of
the reservoirs potentially affecting fish habitat by altering water
depth and ultimately the volume of cold water habitat necessary for
some sport fish. The effects of such a situation would be exacerbated
by drought conditions similar to the one experienced in recent years.
Steps to preserve cold water habitat within Lake Sakakawea were
undertaken by the Corps in 2005 and 2006 by (1) modifying the trash
racks on 2 of the 5 penstocks, (2) closing 2 of the 10 passage gates to
restrict the opening to the dam's power tunnels, and (3) altering the
release schedule. The effects of sedimentation on the aquatic resources
including the fisheries are discussed in greater detail under a
separate task.
Other effects of siltation occurring in areas other than boat ramps
include modified stream channels and bathymetry which can have negative
effects on water quality (shallow water equals warmer water which in
turn could affect the fishery). Additionally, as sedimentation
accumulates and point bars rise, and as water levels decline with the
recent drought conditions, the area of land susceptible to overgrowth
by invasive species increases, which can cause more problems (USACE
2007).
In reviewing existing USACE reports on sedimentation in the
Missouri River, the areas of the river impacted most by the
accumulation of sediments occur approximately 10 to 15 miles downstream
from the upstream end of the lake zones (Lake Sakakawea and Lake Oahe)
created by the Garrison and Oahe Dams. Most of the sediment
accumulation is concentrated within a 30-mile reach of these points
(Berger, 2008). A tremendous amount of sediment, including sediment
from all upstream tributaries has accumulated in the headwaters of Lake
Sakakawea (estimated annual deposit rate of 26,000 acre-feet annually)
and has buried the old river channel downstream (NDGF 2002). Lower
elevations in Lake Sakakawea do not provide additional riverine habitat
but rather exposes vast expanses of accumulated sediments (NDGF 2002).
Figure 6-1. shows the locations of formal recreation access sites
with the sediment aggradation areas. According to the sediment
aggradation maps, nearly all of the intensive use recreation sites on
Lake Sakakawea are in areas of the lake with low to moderate
sedimentation levels. On Lake Oahe, Graner Park Recreation Area and
Kimball Bottom Recreation Area are areas of intense recreational use
that are affected by high levels of sedimentation. MacLean Bottom
Recreation Area is also identified as an area with high sedimentation
levels but the site is considered a low density recreation area. In
all, 1.1 million visitors recreated at sites within areas identified as
either ``low'' or ``moderate'' areas of sediment aggradation on Lake
Sakakawea and an additional 2.3 million visitors recreated at similarly
identified sites in Lake Oahe according to the aggradation maps
(Berger, 2008).
The USACE provides high, mid, and low water ramps at many of the
access areas to accommodate changes in reservoir levels which also
provides alternative access during periods when ramps are covered with
sediment. Most recently Fort Stevenson State Park, Government Bay, and
Sanish Bay were locations within the reservoir impacted by sediment on
the boat ramps affecting boater access. The Fort Stevenson West Ramp
(low water ramp) was closed because it was entirely silted in, however
a brand new marina ramp is being constructed on the northwest side of
the park. Fort Stevens State Park is approximately 3 miles south of the
town of Garrison; however it is not known if sediment is being loaded
into the arm from tributary or in-reservoir sources. Government Bay and
Sanish Bay were locations within the reservoir that required dredging
to provide boater access. The Government Bay low water ramp was
completely reconstructed within the last year because of siltation
problems as the bay is filling up with silt and there is no longer a
good location for moving the boat ramp. Complicating matters, the ramp
cannot be extended because of a lack of room. In general, USACE's
recent solution has been to move or extend ramps rather than continue
to dredge out areas, because it is less expensive (Linda Phelps, USACE
personal communication). These areas are within bays or smaller arms
that are subject to local sedimentation processes and were not
identified as areas of aggradation by the earlier Berger (2008) report
that focused on changes in the elevations within the main channel and
thalweg.
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 6-1.--Developed Recreational Sites within Aggragation Areas
Recent drought conditions have resulted in lower than normal lake
levels in Lake Oahe changing the upstream character of the reservoir
from a reservoir to that of riverine character. According to the USACE,
channel shifting and erosion is occurring at Kimball Bottoms Recreation
Area and MacLean Bottoms Recreation Area, limiting recreation access by
undercutting the boat ramps or leaving them out of the water as the
channel migrates away from the access area. Boat ramps and land based
amenities need some level of protection and support from erosion
processes. Rip rap has been installed over the years along the east
side of Lake Oahe to protect the recreation sites from erosive
processes; however this can be challenging in light of large
fluctuations in reservoir elevations.
7.0 SUMMARY AND RECOMMENDATIONS
Erosion of the Missouri River above Lake Sakakawea and below
Garrison dam poses the same problems in that sediment is moved in the
channel and deposited in areas of calm water. When the reservoir is
full, sediment is typically deposited further up the river but when the
reservoir is down the channel is eroded and those sediments are moved
within the channel downstream.
Drought conditions and sedimentation/siltation processes can result
in park or access closures preventing recreational access to areas
within the reservoirs, directly impacting the recreation resources. The
loss of boater access results in longer drives to launch boats, trip
cancellation, poor aesthetics, and safety hazards to those using the
Missouri River. Boat access site managers are forced to spend an
increasing amount of time and resources to operate and maintain the
boat ramps free of sediments to maintain boater access. Bays or arms
just off the main channel have historically been the primary location
of boater access; however these areas are susceptible to sediment
aggradation as reported in interviews conducted for this research. It
is important to note that these areas were not identified by the
sediment aggradation modeling tool so the number of visitors affected
by siltation is likely much higher. It is also important to remember
that siltation can be a nuisance at boat ramps; however the reservoirs
still provide greatest amount of flat water recreation opportunities in
the state of North Dakota so that once on the water, recreationists may
still report satisfactory trips.
Successfully addressing sedimentation issues within the Missouri
River will likely require a holistic approach and recommendations
pertaining to the recreation resources would be a part of that
solution. Lake Sakakawea and Lake Oahe are relatively young reservoirs
and areas identified upon their creation as good or suitable recreation
sites (e.g., within bays or off channel arms) have subsequently filled
in with sediments. This process is likely to continue into the future
until sediment sources and in-reservoir sediment processes like
shoreline erosion stabilize. Until then, identifying alternative boat
ramp areas within existing parks may alleviate some maintenance of
dredging ramps open and should be pursued when long term planning is
initiated for the access sites. For example rebuilding boat ramps in
areas less susceptible to sediment aggradation may have expensive up
front costs; however the overall costs may be lower if there is no need
for additional dredging of the ramps on a regular basis. As such, we
recommend that strategic planning efforts identify and target areas
that are currently susceptible to sediment aggradation, are close to
population centers (e.g. Fort Stevens State Park) and have alternative
ramp sites that would result in less sediment aggradation on the ramps.
Permanent ramp closures is a viable option for access sites that do not
have viable alternative locations for new ramps and have regular
dredging needs.
USACE maintains a Web site for the boat ramps on Lake Sakakawea and
Lake Oahe that informs visitors of the reservoir depth and whether or
not ramps are available for use. This is beneficial for visitors
because it provides a method to check accessibility and plan trips in
advance. We recommend that USACE continue to utilize the Web site
planning tool. Although designed primarily for reservoir elevations,
this trip planning tool possesses the ability to report closures due to
sediment build up as well. Although not likely of interest to visitors,
this could provide a way for the USACE to monitor sediment related
closures.
Boat ramps have been extended or relocated to accommodate for low
water levels. Extension or relocation would also accommodate for
sedimentation build up at boat ramps within the study area. Siltation
of boat ramps and erosion in other areas along the Missouri River is
occurring in certain areas posing a nuisance to some of the open water
areas; however, overall there are tremendous opportunities in the area
for flat water recreation and access to the reservoirs and rivers.
Table 7-1 summarizes the key findings related to the objectives of this
task.
TABLE 7-1.--IMPACT OF SEDIMENTATION ON RECREATION RESOURCES
----------------------------------------------------------------------------------------------------------------
Direct Impact Significance Timeline Recommendations
----------------------------------------------------------------------------------------------------------------
Ramp or Access Closure......... The lack of boater access Parks and access areas (1) Identify and
results in longer drives are predominantly used prioritize areas, for
to launch boats, trip in the summer therefore long term planning
cancellation, poor summer time would have purposes, that are
aesthetics, and safety the greatest level of currently susceptible to
hazards to those using impact, however because sediment aggradation and
the Missouri River. Boat sedimentation processes are close to population
access site managers are occur throughout the centers (e.g. Fort
forced to spend an year, impacts to access Stevens State Park) and
increasing amount of areas would be on-going. identify alternative
time and resources to ramp sites that would
operate and maintain the result in less
boat ramps free of aggradation on the
sediments to maintain ramps.
boater access. (2) Additional study of
visitor's willingness to
travel in the event that
popular boat ramps are
closed and the proximity
to nearby alternatives.
(3) Evaluate extending or
relocate boat ramps
depending on the first
parts above.
(4) Evaluate closing
ramps at sites that do
not have viable
alternative locations
for new ramps and have
regular dredging needs.
Underwater hazards............. Shallow water due to Dynamic and dependent on Evaluate options of
sediment deposition pose reservoir elevations. educating the boating
a risk to boaters and Summer peak boating public, signage and
boating equipment. season with low lake updating bathymetric
levels pose the greatest mapping efforts.
risk.
----------------------------------------------------------------------------------------------------------------
Literature Cited
The Louis Berger Group, Inc. Identification of Sources and Deposits
and Locations of Erosion and Sedimentation. August 22, 2008.
North Dakota Parks and Recreation Department. 2007. North Dakota
State Comprehensive Outdoor Recreation Plan 2008-2012. North Dakota
Parks and Recreation Department, Bismarck, ND. 2008.
North Dakota Game and Fish Department. 2007a. Angler Use and Sport
Fishing Catch Survey on Lake Sakakawea, North Dakota May 1 through
September 30, 2006. Written by: Larry Brooks, Jeff Hendrickson, and
Dave Fryda. Project F-2-R-53, Bismarck, North Dakota.
North Dakota Game and Fish Department. 2007b. Angler Use and Sport
Fishing Catch Survey on the Missouri River and Lake Oahe, North Dakota
April 1 through October 31, 2006. Larry Brooks, Jeff Hendrickson, and
Dave Fryda. Project F-2-R-53, Bismarck, North Dakota.
North Dakota Game and Fish Department. 2002. Official Department
Position Papers; The Missouri and Yellowstone Rivers In North Dakota
(Williston Reach)--A Report to the Director, 2002.
North Dakota State Water Commission. 2005. A Reference Guide to
Water in North Dakota. North Dakota State Water Commission, Governor
John Hoeven, Chairman and Dale L. Frink, State Engineer. Bismarck,
North Dakota.
USACE (U.S. Army Corps of Engineers). 2008a Geographic Information
System Recreation site information. Obtained via email communication
between Eric Morrison, GIS specialist, Omaha District, USACE and Brian
Lee, The Louis Berger Group, Inc. October 7, 2008.
USACE (U.S. Army Corps of Engineers). 2008b Visitor Use
Information. Obtained via email communication between Jerald L.
Alexander, Natural Resource Specialist, Omaha District, USACE and Jot
Splenda, The Louis Berger Group Inc., October 16, 2008.
USACE (U.S. Army Corps of Engineers). 2007. Garrison Dam/Lake
Sakakawea Master Plan with Integrated Programmatic Environmental
Assessment. U.S. Army Corps of Engineers--Omaha, District. Missouri
River, North Dakota.
USACE (U.S. Army Corps of Engineers). 2007. Preliminary Draft Oahe
Dam/Lake Oahe Master Plan Missouri River, South Dakota and North
Dakota. U.S. Army Corps of Engineers--Omaha, District. Riverdale, North
Dakota.
USACE (U.S. Army Corps of Engineers). 2005. Lake Sakakawea Garrison
Dam Boat and Recreation Guide. U.S. Army Corps of Engineers--Omaha,
District. Riverdale, North Dakota.
USACE (U.S. Army Corps of Engineers). 2003. Operational Management
Plan Garrison Project. Appendix F: Shoreline Management Plan. U.S. Army
Corps of Engineers--Omaha, District. Riverdale, North Dakota.
USACE (U.S. Army Corps of Engineers). 2003. Lake Oahe Dam Boat and
Recreation Guide. U.S. Army Corps of Engineers--Omaha, District.
Riverdale, North Dakota.
USGS 2008. Missouri River Basin in North Dakota USGS Web site. Web
site accessed at: http://nd.water.usgs.gov/missouririver/index.html.
Web site accessed on November 14, 2008. Web site updated July 28, 2008.
Other Information Sources:
Minnesota Public Radio. Water Wars: Recreation on the Missouri
River. Dan Gunderson. 2003. (http://news.minnesota.publicradio.org/
features/2003/07/03_gundersond_riverrecreation/).
North Dakota Game and Fish Department. 2002-2007. Fisheries
Management Plan Missouri River System. Jeff Hendrickson, Jason Lee,
Dave Fryda, Greg Power, and Fred Ryckman. North Dakota Game and Fish
Department, Bismarck, North Dakota.
USACE (U.S. Army Corps of Engineers). 2008. Bank Stabilization
Cumulative Impact Analysis Final Technical Report. U.S. Army Corps of
Engineers, Omaha, Nebraska.
USACE (U.S. Army Corps of Engineers). 2008. Quarterly Drought
Report. U.S. Army Corps of Engineers--Omaha, District. Riverdale, North
Dakota.
USACE (U.S. Army Corps of Engineers). Revised 2006. Missouri River
Mainstem Reservoir System Master Water Control Manual Missouri River
Basin. U.S. Army Corps of Engineers, Reservoir Control Center
Northwestern Division--Missouri River Basin. Omaha, Nebraska.
appendix d--impact of siltation on hydropower generation, missouri
river, north dakota
EXECUTIVE SUMMARY
This report assesses the impacts of siltation in the Missouri River
Basin within the State of North Dakota on hydropower facilities and
operations. Hydropower facilities along the Missouri River in North
Dakota consist of the Garrison Dam and its reservoir, Lake Sakakawea.
In addition, hydropower operations in North Dakota are affected by the
operation of Oahe Dam in South Dakota because Lake Oahe extends into
southern North Dakota up to just south of the city of Bismarck when the
pool is full.
Hydropower Facilities
The two reservoirs are part of the Missouri River Mainstem System
(System) consisting of six dams in total. Construction of the System
started in the 1930s with the Fort Peck Dam. Garrison Dam was closed in
1953; Oahe Dam was closed in 1958. The Flood Control Act (Pick-Sloan
Act) from 1944 specifies that the reservoirs were to be operated as an
integrated system. Aside from hydropower, other uses are relevant in
the operation of the System: flood control, navigation, irrigation,
recreation, water supply, and fish and wildlife.
The hydropower facilities of the System provide dependable energy
to meet annual peak power demands of the region. Annual gross power
production at the Garrison Dam was on average 2.29 million MWh from
1967 (2 years after Lake Sakakawea was filled) through 2007. However,
hydropower operations at Garrison Dam have generally decreased over
time to 1.31 MWh in 2007 due to drought. The main exception was a
period in the mid-1990s with high precipitation in the upper Missouri
River watershed. Peak months of outflow and thus energy generation are
December, July, and August due to high power demand.
Power release rates are commonly adjusted on a daily basis to
support a variety of uses. The generated electricity is marketed by the
Western Area Power Administration (WAPA) which is an agency of the
Department of Energy (Western). Revenues are highest during the peak
generation months in the winter and summer. The total revenues from
energy generated at Garrison Dam in the last 5 years (2003 to 2007)
ranged from $15 million to $22 million. Highest annual revenues were
generated during the wet year 1996 with $43 million.
Impacts
Potential impacts from siltation in the Missouri River on
hydropower operations in North Dakota consist of the following:
--Loss of Storage in Lake Sakakawea.--Lake Sakakawea traps nearly 100
percent of the sediment that enters the reservoir. Most of the
sediment originates from the Missouri River and the Yellowstone
River, a tributary to the Missouri River. This includes
sediment that is eroded from the bank and bottom of the
Missouri River, downstream of the Fort Peck dam. The USACE
estimated a storage loss rate of 25,900 acre-feet/year (or 0.11
percent per year). At this rate, the life expectancy of Lake
Sakakawea is approximately 900 years before it is completely
filled. This value is a first-order estimate only, as the life
expectancy depends on a number of variables such as sediment
trapping efficiency (which decreases over time), climate
variability over time, and sediment contributions from the
watershed of Fort Peck Dam (sediment from its watershed is
currently trapped in its reservoir).
--Entrainment of Sediment Into the Turbines at Garrison Dam.--With an
annual loss of storage capacity by 0.11 percent, and most of
the deposition occurring in the upper reaches of the reservoir,
impacts to the intakes to the hydropower facility are not
expected for a long time. As a result, the USACE does not have
any specific sediment management methods or sediment control
facilities at their hydroelectric facilities at this time.
--Reduced Releases at Garrison Dam in Winter Due to Flooding Risk
From Sediment Aggradation.--Siltation in the reach between
Garrison Dam and Lake Oahe has resulted in increased risk of
flooding in the downstream reach between the dam and the
headwater of Oahe Lake. The Missouri River typically freezes in
December, remains frozen in January and February, and starts to
thaw in March and April. A large consideration in flow releases
are the potential formation of ice dams. Aggradation of the
river channel in the headwaters of Lake Oahe has resulted in a
slightly greater decrease in energy production in the colder
months of the years than during the warmer months of the year.
Recommendations
Releases from Garrison Dam by the USACE for various uses already
aim to minimize flooding. Detailed monitoring data should continue to
be collected to allow for effective adaptive management measures of the
operations of Garrison Dam to maximize the benefit of the dam and the
overall System, while minimizing impacts. This is particularly
important in light of the fact that there are a number of natural
variables that change regularly (daily, as well as longterm), such as
rainfall, temperature, flow, erosion and deposition patterns, etc. In
addition, the river serves multiple uses that also need to be balanced.
Dredging could be considered on a temporary and localized basis for
flood control, but a larger-scale dredging operation would most likely
be cost-prohibitive.
The risk of flooding will increase once the current drought has
passed, and Lake Oahe again has full pool elevations. Higher pool
elevations imply that sediment carried by the Missouri River will be
settling out closer to the city of Bismarck than at present which will
result in further aggradation. A higher risk of flooding requires
further reduction in hydropower generation at Garrison Dam. The
existing flood plain and zoning should be reviewed in the cities of
Bismarck and Mandan (as well as in non-urban areas in the Garrison Dam
to Lake Oahe reach) to determine if additional steps should be
undertaken to better accommodate high flows in the Missouri River.
Developments close to the river edge should be avoided, or potentially
even reversed if feasible. Further, appropriate bank stabilization
measures should be considered in areas most heavily affected by
flooding.
It is recommended to conduct a study that more quantitatively
demonstrates that higher elevations in Lake Oahe will result in a
decrease in flow velocities due to aggradation. This study would need
to address the range of variables that affect the flow in order to
extract the impact of lake elevations on outflow rates.
1.0 INTRODUCTION
The Louis Berger Group Inc. (Berger) was tasked by the U.S. Army
Corps of Engineers (USACE) to assess impacts of sedimentation in the
Missouri River Basin within the State of North Dakota. This assessment
was intended to meet the level of effort defined in the Missouri River
Protection and Improvement Act. The assessment had two objectives.
First, Berger identified sources and deposit locations of sediment
within the Missouri River Basin in the State of North Dakota, utilizing
existing data and information. Next, the team analyzed the potential
impacts of sedimentation on important issues and resources including:
local, regional and national economies; recreation; hydropower
generation; fish and wildlife; flood control and Indian and non-Indian
historical and cultural sites.
The study area was defined by the USACE to include the watershed of
the mainstem of the Missouri River from the North Dakota-South Dakota
border on the downstream end to the Montana-North Dakota border on the
upstream end (Figure 1-1). The study area was to include tributaries of
the Missouri River, Lake Sakakawea and Lake Oahe.
This report presents the results of Task 5D--Impact of Siltation on
Hydropower Generation. The assessment was based on review of relevant
existing data and information. Further, individuals familiar with
specific aspects of this task were contacted. The following sections
address the results of the task. Section 2 describes the hydropower
facilities in the study area. Section 3 address siltation impacts on
hydropower operations. Section 4 provides some recommendations.
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 1-1.--Location of the study area (Scale: 1 inch = 53 miles).
2.0 HYDROPOWER FACILITIES
2.1 Overview
Hydropower facilities along the Missouri River in North Dakota
consist of Garrison Dam and its reservoir, Lake Sakakawea (Figure 2-1).
In addition, hydropower operations in North Dakota are affected by the
operation of Oahe Dam in South Dakota. Lake Oahe extends into southern
North Dakota, and can extend up to just south of the city of Bismarck
when the pool is full. Oahe Dam is located just to the north of the
city of Pierre in central South Dakota.
Garrison Dam and Oahe Dam and their respective reservoirs are part
of the Missouri River Mainstem System (System) consisting of six dams
in total (Figure 2-2). The other four dams are Fort Peck Dam, Big Bend
Dam, Fort Randall Dam, and Gavins Point Dam. The total drainage area at
Gavins Point Dam is 279,480 square miles (Figure 2-3).
Construction of the System started in the 1930s with the Fort Peck
Dam. The other five dams were authorized in 1944 by the Flood Control
Act (Pick-Sloan Act). This Act specified that the reservoirs were to be
operated as an integrated system. Aside from hydropower, other uses are
relevant in the operation of the System: flood control, navigation,
irrigation, recreation, water supply, and fish and wildlife. In
enacting this Act, Congress did not assign a priority to these
operational purposes, as stated in the recent Record of Decision (ROD)
for the Missouri River Master Control Manual Review and Update (USACE,
2004b). The ROD states further:
``Instead, it was contemplated that the Corps, in consultation with
affected interests and other agencies, would consider all of the
authorized purposes when making decisions to optimize development and
utilization of the water resources of the Missouri River to best serve
the needs of the people.'' (p.1)
The reservoirs in the System have defined zones to facilitate
operations. These zones were developed for flood control, multiple
uses, and the permanent pool (Figure 2-4). The six dams in the System
are operated in an integrated manner to assure that the multi-use goals
can be met. For example, Lake Sakakawea and Lake Oahe are significant
for flood storage as they have the largest storage capacity of the six
impoundments in the System (Figure 2-5).
The reservoir zones are defined as follows (USACE, 2004a):
--Exclusive Flood Control Zone.--This zone is the total upper volume
of the mainstem lakes maintained exclusively for flood control.
The System-wide capacity of this zone is 6 percent. Water is
released from this zone as quickly as downstream channel
conditions permit so that sufficient storage remains available
for capturing future inflows.
--Annual Flood Control and Multiple Use Zone.--This zone is reserved
for annual flood control and multiple uses. The System-wide
capacity of this zone is 16 percent. This zone is used to store
the high annual spring and summer inflows to the lakes in the
System. Later in the year, water stored in this zone is
released for riverine uses so that the zone is evacuated by the
beginning of the next flood season on March 1. Evacuation is
accomplished mainly during the summer and fall navigation
season, because icing of the river may preclude high evacuation
flows during the winter.
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 2-1.--Aerial photograph of Garrison Dam (Source: Google Earth)
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 2-2.--Location of Garrison Dam and Oahe Dam, as part of the
Missouri River Mainstem Reservoir System (USACE, 2004a).
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Source: Missouri River Main Stem Reservoirs, Hydrologic Statistics,
US Army Corps of Engineers, 1999
Figure 2-3.--Total Drainage at Gavins Point Dam
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 2-4.--Reservoir zone locations of the system (schematic) (USACE,
2004a).
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 2-5.--Missouri River mainstem system storage, by mainstem
reservoir (USACE, 2004a).
--Carryover Multiple Use Zone.--This zone is the largest portion of
the System's upper storage capacity, designed to provide water
for all uses during drought periods. This zone is confined to
Fort Peck Lake, Lake Sakakawea, Lake Oahe, and Lake Francis
Case. The System-wide capacity of this zone is 53 percent. The
zone is operated so that it remains full during periods of
normal inflow but is gradually drawn down during drought
periods.
--Permanent Pool.--The remaining total storage capacity (25 percent
System-wide) is reserved as the permanent pool. Total capacity
allocated for the permanent pool is approximately 18 million
acre-feet System-wide. The permanent pool provides the minimal
water level necessary to allow the hydropower plants to operate
and to provide reserved space for sediment storage. It also
serves as a minimum pool for recreation and for fish and
wildlife habitat and as an ensured minimum level for pump
diversion of water from the lakes.
2.2 Physical Characteristics
2.2.1. Garrison Dam and Lake Sakakawea
Garrison Dam is located at river mile (RM) 1390 in central North
Dakota near the Town of Riverdale, approximately 75 river miles
northwest of the city of Bismarck. The dam is 180 feet high and one of
the largest rolled earthfill dams in the world. Its gross storage
capacity is 23.8 million acre-feet (USACE, 2004a). Construction of the
Garrison Project started in 1946. Closure of the dam and thus filling
of Lake Sakakawea occurred in April 1953. Operation of the powerplant
began in 1955. The first three power-generating units were placed on
line in 1956. Units 4 and 5 were placed into operation in October 1960.
Relevant physical characteristics of Garrison Dam, Lake Sakakawea,
and the watershed for the lake are summarized below (USACE, 2000a;
2004a):
--Garrison Dam
--Date of Closure--April 1953
--Height--180 feet
--Width--11,300 feet
--Lake Sakakawea
--Pool Elevations (Figure 2-4):
-- Minimum Operating Pool (Top, Permanent Pool)--1,775.0 ft msl
-- Base Flood Control Level (Top, Carryover and Multiple Use
Zone)--1,837.5 ft msl
-- Maximum Normal Pool (Top, Annual Flood Control and Multiple
Use Zone)--1,850.0 ft msl
-- Maximum Operating Pool (Top, Exclusive Flood Control
Reserve)--1,854.0 ft msl
--Length of Reservoir (full)--178 valley miles
--Maximum Depth (near dam)--180 feet
--Shoreline Length (at 1,837.5 msl)--1,340 miles
--Surface Area (at 1,837.5 msl)--380,000 acres
--Surface Area (full)--593 sq.mi.
--Gross Storage--23,821,000 acre-feet
--Flood Storage--5,711,000 acre-feet
--Carryover Storage--13,130,000 acre-feet
--Mean Annual Outflow of Water
-- Rate--22,800 cfs
-- Volume--15.6 million acre-feet
--Watershed
--Drainage Area for Lake Sakakawea (at Garrison Dam):
-- Including the drainage area of Fort Peck Dam--181,400 sq. mi.
-- Excluding the drainage area of Fort Peck Dam--123,900 sq. mi.
The Fort Peck Dam upstream of Lake Sakakawea was closed in 1937.
Most of the sediment entering the Fort Peck Lake is captured by the
reservoir, thus reducing the drainage area that supplies sediment to
Lake Sakakawea by 32 percent.
2.2.2. Oahe Dam and Lake Oahe
Oahe Dam is located approximately 6 miles to the northwest of the
city of Pierre, South Dakota, at RM 1072. It is 200 feet high and has a
gross storage capacity is 23.1 million acre-feet (Figure 2-5).
Construction of the Oahe Project started in 1948. Closure of the dam
was completed in 1958. The pool was first filled in 1962 and the first
power unit came on line. All power units were operational in July 1966.
Relevant physical characteristics of Lake Oahe are summarized below
(USACE, 2000a; 2004a):
--Oahe Dam
--Date of Closure--August 1958
--Height--200 feet
--Width--9,300 feet
--Lake Oahe
--Pool Elevations (Figure 2-4):
-- Minimum Operating Pool (Top, Permanent Pool)--1,540.0 ft msl
-- Base Flood Control Level (Top, Carryover and Multiple Use
Zone)--1,607.5 ft msl
-- Maximum Normal Pool (Top, Annual Flood Control and Multiple
Use Zone)--1,617.0 ft msl
-- Maximum Operating Pool (Top, Exclusive Flood Control
Reserve)--1,620.0 ft msl
--Length of Reservoir (full)--231 valley miles
--Gross Storage--23,137,000 acre-feet
--Flood Storage--4,303,000 acre-feet
--Carryover Storage--13,461,000 acre-feet
--Watershed
--Drainage Area for Lake Oahe (at Oahe Dam)
-- Including the drainage area of Garrison Dam--243,490 sq. mi.
-- Excluding the drainage area of Garrison Dam--62,090 sq. mi.
2.3 Power Generation
Most of the water stored in Lake Sakakawea is eventually moved
through the reservoir system which enables power production (USACE,
2004a). Runoff between March and July supplies 70 percent of the water
used for annual power generation. Water is only bypassed during larger
magnitude inflow years.
2.3.1. Garrison Dam and Lake Sakakawea
The primary water management functions of Garrison Dam and Lake
Sakakawea are as follows (USACE, 2006, Paragraph 7-02.3, p. VII-3):
``7.02-3. . . . (1) to capture the snowmelt runoff and localized
rainfall runoffs from the large drainage area between Fort Peck and
Garrison Dams that are then metered out at controlled release rates to
meet System requirements, while reducing flood damage in the Garrison
Dam and Lake Oahe reach, particularly the urban Bismarck area;
``(2) to serve as a secondary storage location for water
accumulated in the System from reduced System releases due to major
downstream flood control regulation, thus helping to alleviate large
reservoir level increases in Oahe and Fort Randall; and
``(3) to provide the extra water needed to meet all of the System's
Congressionally authorized project purposes that draft storage during
low water years.''
There are general requirements for power generation as specified in
the Garrison Standing Order from 1983 (Exhibit 1). This order specifies
minimum releases for specific time periods. For example, over a 4 hour
period, 300 MWh must be generated. The release pattern within these 4
hours to achieve at least 300 MWh can be chosen by WAPA. This
requirement is designed to assure that municipal and industrial water
intakes between Garrison Dam and Lake Oahe have sufficient water. There
are a total of 123 intakes between Garrison Dam and Lake Oahe, which
consist of 6 power plant intakes, 3 municipal water supply facilities,
6 industrial intakes, 77 irrigation intakes, 28 domestic intakes, and 3
public intakes (USACE, 2006). Another requirement states that
supplementary releases are only to be made as necessary to maintain a
daily average release rate of 6,000 cfs at Garrison Dam.
In addition to the Standing Order, the USACE provides WAPA with
daily reservoir regulation and power production orders. These orders
ensure that requirements for other uses as well as hydrological and
meteorological conditions at the time are incorporated. For example, in
summer, typically between May 15 and August 30, the shape of the
releases is controlled due to nesting of endangered bird species below
the Garrison Dam. This limits the peaking pattern for power generation.
Also, in winter, release rates are determined based on requirements for
ice-in and flood control conditions.
Releases at Garrison Dam in the winter that are affected by flood
control considerations are defined in the Master Water Control Manual
(USACE, 2006, p. VII-17) as follows:
``7-04.7.1. Fort Peck and Garrison Flood Control Considerations.
The winter season is the time period when the firm power demand from
the System is the greatest. To enhance winter energy generation, winter
releases from the upstream Fort Peck and Garrison reservoirs are often
maintained at the maximum level possible that is consistent with
downstream channel capacity. During the winter, channel capacity is
reduced because of threat of flooding during river ice formation or
when an established Missouri River ice cover raises Missouri River
stages. Because of the somewhat unpredictable behavior of a downstream
ice cover, the exact potential volume of winter releases from these
upstream projects cannot be estimated accurately. Prewinter System
reservoir storage levels are scheduled on the basis that the
established winter release rate will be made most of the time through
these upstream powerplants. If channel conditions during the winter are
such that the established winter release rate assumed in prewinter
scheduling is not possible, a release deviation will be implemented.
The changed release rate may result in some imbalance in the amount of
water-in-storage in individual System reservoirs by the following
spring. This storage imbalance will favor the downstream flood control
purpose, with additional evacuated storage space located in the largest
downstream System project, Oahe. This is not a matter of great concern
because open-water channel capacities below Fort Peck and Garrison are
sufficient to allow a relatively fast restoration of System storage
balance following the ice breakup if attaining a balance in the amount
of water-in-storage at the large upper three reservoirs is still a goal
at that time of the season.''
Additional considerations during the winter ice season, as they
affect flow releases and thus hydropower generation, consist of the
following (USACE, 2006, p. VII-19):
``7-04.9. System Regulation Considerations During Winter Ice
Season. The maximum flow that may be passed without damage varies
through the length of the Missouri River and is dependent on channel
dimensions, the degree of encroachment onto the floodplain, and
improvements such as levees and channel modifications. Capacities at
specific locations also vary from season to season, especially in the
middle and upper river reaches, where a decrease in capacity due to the
formation of an ice cover is common through the winter and early spring
months. Like with most streams, the capacity of the Missouri River
channel usually increases progressively downstream, although instances
occur where this trend is reversed.''
7-04.9.4. Ice cover forming on the Missouri River below Fort Peck,
Garrison, and Oahe Dams has a marked effect on the winter regulation of
these projects. At the time the ice cover first forms below Fort Peck
and Garrison Dams, the downstream channel capacities are at a minimum.
As the river ice cover stabilizes, flows are normally slowly increased
followed by a progressive increase in the channel capacity that
continues until just prior to the end of the winter season. It is often
possible to increase releases while maintaining relatively constant
downstream stages. This phenomenon is discussed in more detail in two
RCC Technical Reports, ``Freezing of the Missouri River Below Garrison
Dam,'' February 1973, and ``Freezing of the Missouri River Below Fort
Peck Dam,'' July 1973. (p. VII-20 to 21)
Lake Sakakawea reached its minimum operating level (1,775 feet msl)
in late 1955. The Carryover Zone and Multiple Use Zone was reached only
10 years later, in 1965, due to drought conditions (Figure 2-6). The
lake remained generally filled from that time through 1976. Exclusive
Flood Control storage space (1,854 feet msl) was used in 1969, 1975,
1995, and 1997. During 1975, all flood control space was filled and the
maximum reservoir level was 0.8 feet above the base of the surcharge
pool. Since then the reservoir elevation has dropped to below the
Carryover Zone and Multiple Use Zone, specifically in the periods
between 1987 and 1993, and from 2000 to the present (Figure 2-7; Table
2-1).
The minimum and maximum monthly elevations on Lake Sakakawea have a
range of approximately 5 to 15 feet on an annual basis (Figure 2-8).
During the winter months (December to February), elevations vary only
by a few feet due to the ice cover (Figure 2-9).
The power generation facilities are owned and operated by the U.S.
Government. The Western Area Power Administration (WAPA; discussed in
more detail in Section 2.4 below) markets and transmits the energy
produced by the facility and thus requests releases from the operators
within USACE specified requirements.
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 2-6.--End-of month pool elevations in Lake Sakakawea between
closure of Garrison Dam in 1953 and 1993 (Source: USACE, 1993a).
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 2-7.--End-of month pool elevations in Lake Sakakawea between
1967 (2 years after reservoir was filled) and the present (Source of
data: USACE).
TABLE 2-1.--END-OF-MONTH ELEVATION OF LAKE SAKAKAWEA, JUNE 1967 TO SEPTEMBER 2008 (IN FEET msl)
[Retrieved on 8-October-2008]
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
MONTH FULL YEAR (Jan-Dec) Colder Months (Dec-Apr) \1\
YEAR -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MIN MAX MEAN MIN MAX MEAN
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1967................................................ ........ ........ ........ ........ ........ 1,845.0 1,849.5 1,846.2 1,844.9 1,842.9 1,841.5 1,839.2 ........ ........ ........ 1,835.8 1,839.2 1,837.6
1968................................................ 1,837.3 1,835.8 1,838.4 1,837.2 1,836.7 1,843.8 1,846.7 1,847.2 1,847.1 1,845.2 1,844.5 1,842.6 1,835.8 1,847.2 1,841.9 1,838.1 1,842.6 1,840.6
1969................................................ 1,840.3 1,838.1 1,839.3 1,842.6 1,844.7 1,848.0 1,850.5 1,848.5 1,846.6 1,844.9 1,843.4 1,840.7 1,838.1 1,850.5 1,844.0 1,837.3 1,840.7 1,838.2
1970................................................ 1,838.4 1,837.5 1,837.3 1,837.3 1,839.9 1,846.1 1,848.8 1,847.1 1,846.8 1,845.6 1,844.0 1,842.0 1,837.3 1,848.8 1,842.6 1,839.9 1,843.6 1,841.8
1971................................................ 1,839.9 1,840.4 1,843.3 1,843.6 1,843.0 1,848.3 1,848.8 1,847.1 1,846.5 1,846.6 1,845.4 1,843.4 1,839.9 1,848.8 1,844.7 1,840.2 1,847.7 1,843.8
1972................................................ 1,841.3 1,840.2 1,847.7 1,846.5 1,845.8 1,848.8 1,848.9 1,848.7 1,847.9 1,847.3 1,846.7 1,845.3 1,840.2 1,848.9 1,846.3 1,842.8 1,845.3 1,843.7
1973................................................ 1,843.6 1,842.8 1,843.4 1,843.2 1,845.5 1,848.9 1,848.7 1,847.2 1,846.8 1,845.6 1,843.8 1,842.3 1,842.3 1,848.9 1,845.2 1,838.6 1,842.3 1,840.0
1974................................................ 1,840.4 1,839.0 1,838.6 1,839.8 1,840.5 1,846.6 1,849.0 1,847.9 1,847.1 1,845.1 1,844.0 1,842.3 1,838.6 1,849.0 1,843.4 1,838.7 1,842.7 1,840.7
1975................................................ 1,841.0 1,839.0 1,838.7 1,842.7 1,846.2 1,851.3 1,854.8 1,851.2 1,848.2 1,846.2 1,844.0 1,842.0 1,838.7 1,854.8 1,845.4 1,840.4 1,842.5 1,841.6
1976................................................ 1,840.9 1,840.4 1,842.5 1,842.4 1,843.2 1,847.8 1,848.0 1,846.2 1,845.1 1,843.5 1,841.7 1,840.0 1,840.0 1,848.0 1,843.5 1,835.8 1,840.0 1,837.1
1977................................................ 1,837.3 1,836.2 1,836.1 1,835.8 1,836.0 1,837.7 1,836.9 1,835.6 1,835.2 1,834.8 1,833.0 1,831.0 1,831.0 1,837.7 1,835.5 1,825.7 1,836.0 1,830.5
1978................................................ 1,828.0 1,825.7 1,831.7 1,836.0 1,842.5 1,847.5 1,849.3 1,847.0 1,845.7 1,843.8 1,840.9 1,839.8 1,825.7 1,849.3 1,839.8 1,834.9 1,843.9 1,838.5
1979................................................ 1,836.8 1,834.9 1,837.0 1,843.9 1,844.8 1,845.3 1,846.0 1,845.6 1,844.6 1,844.3 1,843.1 1,842.2 1,834.9 1,846.0 1,842.4 1,837.1 1,842.2 1,839.1
1980................................................ 1,840.5 1,838.5 1,837.3 1,837.1 1,837.6 1,839.7 1,839.4 1,838.4 1,837.9 1,837.1 1,835.6 1,833.6 1,833.6 1,840.5 1,837.7 1,828.5 1,833.6 1,830.9
1981................................................ 1,832.3 1,830.5 1,829.6 1,828.5 1,829.8 1,835.5 1,835.3 1,834.1 1,833.3 1,833.3 1,834.0 1,832.9 1,828.5 1,835.5 1,832.4 1,829.0 1,834.3 1,831.4
1982................................................ 1,830.6 1,829.0 1,830.1 1,834.3 1,834.8 1,840.5 1,845.0 1,845.3 1,845.0 1,845.5 1,843.0 1,842.0 1,829.0 1,845.5 1,838.8 1,839.5 1,842.0 1,841.0
1983................................................ 1,841.7 1,841.2 1,840.7 1,839.5 1,839.9 1,843.3 1,846.6 1,845.0 1,843.1 1,843.4 1,843.2 1,841.4 1,839.5 1,846.6 1,842.4 1,839.1 1,841.4 1,839.9
1984................................................ 1,840.0 1,839.1 1,839.5 1,839.5 1,842.4 1,847.7 1,849.2 1,847.2 1,845.2 1,844.6 1,843.2 1,841.6 1,839.1 1,849.2 1,843.3 1,838.1 1,841.6 1,839.6
1985................................................ 1,840.0 1,838.1 1,838.9 1,839.3 1,840.1 1,841.2 1,840.1 1,839.6 1,838.4 1,838.6 1,837.1 1,835.7 1,835.7 1,841.2 1,838.9 1,833.0 1,836.6 1,835.2
1986................................................ 1,834.3 1,833.0 1,836.6 1,836.6 1,840.5 1,846.5 1,848.4 1,846.3 1,846.3 1,846.4 1,844.7 1,843.5 1,833.0 1,848.4 1,841.9 1,840.1 1,843.5 1,841.7
1987................................................ 1,841.5 1,840.1 1,841.0 1,842.2 1,843.2 1,843.1 1,842.7 1,841.6 1,840.5 1,839.7 1,839.1 1,837.3 1,837.3 1,843.2 1,841.0 1,831.0 1,837.3 1,833.8
1988................................................ 1,835.2 1,833.0 1,832.7 1,831.0 1,831.2 1,832.2 1,830.2 1,827.4 1,825.9 1,825.0 1,824.7 1,823.2 1,823.2 1,835.2 1,829.3 1,820.1 1,823.6 1,822.1
1989................................................ 1,821.8 1,820.1 1,822.0 1,823.6 1,824.8 1,826.7 1,825.9 1,823.4 1,823.0 1,823.8 1,823.2 1,821.1 1,820.1 1,826.7 1,823.3 1,819.2 1,821.1 1,819.9
1990................................................ 1,819.8 1,819.2 1,820.3 1,819.2 1,819.4 1,821.9 1,822.9 1,821.1 1,821.0 1,821.6 1,821.9 1,819.7 1,819.2 1,822.9 1,820.7 1,815.6 1,819.7 1,817.0
1991................................................ 1,817.6 1,815.7 1,816.6 1,815.6 1,817.8 1,826.4 1,828.7 1,826.5 1,826.5 1,827.3 1,826.7 1,824.8 1,815.6 1,828.7 1,822.5 1,820.8 1,824.8 1,822.2
1992................................................ 1,822.4 1,820.8 1,821.8 1,821.3 1,821.4 1,823.4 1,824.9 1,823.0 1,821.8 1,821.3 1,821.3 1,818.8 1,818.8 1,824.9 1,821.9 1,816.8 1,820.5 1,818.5
1993................................................ 1,816.9 1,816.8 1,819.4 1,820.5 1,822.9 1,828.8 1,835.6 1,837.1 1,837.2 1,837.2 1,837.1 1,837.0 1,816.8 1,837.2 1,828.9 1,836.2 1,842.0 1,838.6
1994................................................ 1,836.5 1,836.2 1,841.3 1,842.0 1,843.8 1,845.0 1,843.5 1,841.3 1,839.8 1,840.3 1,838.7 1,837.8 1,836.2 1,845.0 1,840.5 1,835.5 1,837.8 1,836.5
1995................................................ 1,836.0 1,835.5 1,836.5 1,836.5 1,839.9 1,846.5 1,851.6 1,849.2 1,845.6 1,842.8 1,840.4 1,838.9 1,835.5 1,851.6 1,841.6 1,837.8 1,842.9 1,840.2
1996................................................ 1,837.8 1,839.5 1,841.8 1,842.9 1,842.9 1,848.2 1,849.0 1,845.8 1,842.3 1,840.8 1,839.9 1,838.9 1,837.8 1,849.0 1,842.5 1,838.0 1,847.5 1,841.6
1997................................................ 1,838.0 1,839.4 1,844.4 1,847.5 1,847.8 1,853.7 1,852.2 1,849.9 1,846.9 1,843.4 1,841.4 1,840.7 1,838.0 1,853.7 1,845.4 1,839.3 1,840.7 1,839.6
1998................................................ 1,839.3 1,839.3 1,839.4 1,839.3 1,839.2 1,840.8 1,843.0 1,842.6 1,841.6 1,842.3 1,841.8 1,840.4 1,839.2 1,843.0 1,840.8 1,838.9 1,841.7 1,840.3
1999................................................ 1,839.5 1,838.9 1,841.7 1,840.8 1,842.0 1,846.3 1,847.1 1,845.5 1,844.1 1,844.0 1,842.0 1,840.6 1,838.9 1,847.1 1,842.7 1,836.0 1,840.6 1,838.2
2000................................................ 1,839.3 1,837.7 1,837.3 1,836.0 1,835.6 1,838.0 1,837.4 1,834.6 1,833.1 1,832.7 1,830.5 1,829.0 1,829.0 1,839.3 1,835.1 1,828.3 1,830.9 1,829.5
2001................................................ 1,828.7 1,828.3 1,830.4 1,830.9 1,831.6 1,833.8 1,834.4 1,832.8 1,831.8 1,831.1 1,830.5 1,829.2 1,828.3 1,834.4 1,831.1 1,826.9 1,829.2 1,827.9
2002................................................ 1,828.3 1,827.6 1,826.9 1,827.5 1,828.3 1,831.4 1,831.4 1,829.2 1,827.5 1,826.6 1,824.6 1,822.5 1,822.5 1,831.4 1,827.7 1,819.7 1,822.5 1,821.5
2003................................................ 1,821.1 1,819.7 1,822.4 1,821.7 1,822.6 1,827.0 1,826.1 1,822.9 1,820.9 1,820.1 1,819.1 1,818.4 1,818.4 1,827.0 1,821.8 1,814.3 1,818.4 1,815.9
2004................................................ 1,816.7 1,814.3 1,815.6 1,814.7 1,815.3 1,816.5 1,816.5 1,814.3 1,813.3 1,813.1 1,812.3 1,810.0 1,810.0 1,816.7 1,814.4 1,806.6 1,810.0 1,808.4
2005................................................ 1,808.4 1,808.2 1,808.7 1,806.6 1,808.8 1,814.9 1,817.2 1,815.8 1,814.1 1,814.0 1,813.5 1,812.0 1,806.6 1,817.2 1,811.9 1,810.6 1,812.5 1,811.4
2006................................................ 1,811.4 1,810.6 1,810.7 1,812.5 1,814.7 1,817.4 1,815.5 1,812.1 1,809.5 1,809.6 1,808.9 1,807.8 1,807.8 1,817.4 1,811.7 1,806.9 1,808.7 1,807.8
2007................................................ 1,807.0 1,806.9 1,808.7 1,808.6 1,813.1 1,818.1 1,816.9 1,814.6 1,813.7 1,813.2 1,812.7 1,810.9 1,806.9 1,818.1 1,812.0 1,807.3 1,810.9 1,808.5
2008................................................ 1,809.1 1,807.6 1,807.6 1,807.3 1,810.2 1,819.6 1,825.6 1,825.5 1,825.6 ........ ........ ........ ........ ........ ........ ........ ........ ........
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- STATISTICS (JANUARY 1968 TO DECEMBER 2007)
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------NUM................................................. 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40
MIN................................................. 1,807.0 1,806.9 1,808.7 1,806.6 1,808.8 1,814.9 1,815.5 1,812.1 1,809.5 1,809.6 1,808.9 1,807.8 1,806.6 1,816.7 1,811.7 1,806.6 1,808.7 1,807.8
MEAN................................................ 1,832.2 1,831.2 1,832.7 1,833.2 1,834.5 1,838.4 1,839.3 1,837.6 1,836.4 1,835.8 1,834.6 1,833.1 1,829.7 1,839.9 1,834.9 1,830.1 1,834.1 1,831.9
MAX................................................. 1,843.6 1,842.8 1,847.7 1,847.5 1,847.8 1,853.7 1,854.8 1,851.2 1,848.2 1,847.3 1,846.7 1,845.3 1,842.3 1,854.8 1,846.3 1,842.8 1,847.7 1,843.8
STDEV............................................... 10.3 10.4 10.6 11.0 10.8 10.9 11.4 11.7 11.6 11.2 10.9 11.0 10.6 11.2 10.7 10.9 11.4 11.1
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Rows include Jan to Apr of following year.
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 2-8.--End-of-month pool elevations in Lake Sakakawea; monthly
mean, minimum and maximum for each year (Source of data: USACE).
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 2-9.--End-of-month pool elevations in Lake Sakakawea; monthly
mean, minimum and maximum in winter only (Dec-Feb) for each year
(Source of data: USACE).
Outflows from Lake Sakakawea at Garrison Dam are commonly through
the power facilities. The power facilities have a normal capacity of
38,000 cfs and a maximum capacity of 41,000 cfs (USACE, 2008). The
average outflow is 22,800 cfs, resulting in an annual plant factor of
approximately 60 percent (USACE, 2006). In 1975 and 1997, record high
runoff in the upper Missouri River watershed required outflows of
65,000 cfs and 59,000 cfs, respectively, which partially bypassed the
power facilities. The minimum mean daily release rate since 1956
occurred in 1997 at 4,100 cfs (USACE, 2006).
Flows in spring and fall may be reduced to between 10,000 and
15,000 cfs during droughts to conserve water; this rate provides the
minimum protection of water supply intakes, water quality, irrigation
needs, recreation, and fish and wildlife (USACE, 2004a). Flows may be
20,000 to 30,000 cfs during flood evacuation periods. Flows are also
sensitive to bird nesting (USACE, 2004a, p. 3-12):
``To discourage terns and plovers from nesting too near the water
during the mid-May through August nesting period, daily releases are
usually fixed at a constant rate in the 19,000 to 26,000 cfs range with
hourly peaking limited to 6 hours a day near 30,000 cfs. This release
pattern restricts hydropower capacity to less than full powerplant
capacity. During prolonged droughts, daily average releases for the
birds may be in the 10,000 to 15,000 cfs range with peaking restricted
even further. During large system inflow years, large flood control
evacuation release rates are necessary and nesting flow restrictions
are lifted.''
Garrison Dam has a five unit power plant. The combined generating
capacity of the five turbines at Garrison Dam is 583.3 MW (Jody Farhat,
pers. communication, November 14, 2008). This reflects a recent upgrade
from previously 518 MW (USACE, 2006).
Annual gross power generation at Garrison Dam was on average 2.29
million MWh from 1967 (2 years after Lake Sakakawea was filled) through
2007 (Table 2-2).\1\ During this time, the annual power generation at
the dam has ranged from 1.31 million MWh in 2007 to 3.35 million MWh in
1975 (Figures 2-10 and 2-11). In general, power generation has
decreased over time, largely as a function of decreased runoff in the
watershed caused by drought. The exception occurred during the mid-
1990s when spring snowmelting and high rainfall in the Upper Missouri
River watershed resulted in high power generation rates.
---------------------------------------------------------------------------
\1\ Net energy generation is consistently about 99.5 percent of
gross energy generation. The difference between gross and net is that
gross includes generator loss through the transformers and the amount
of power the plant uses (station service) to generate the power (James
Mueller, USACE, personal communication, January 8, 2009).
---------------------------------------------------------------------------
On a monthly basis, the range between minimum and maximum monthly
power generation is generally greater with higher total annual
generation (Figure 2-12). The lowest monthly generation during any year
since 1967 was 82,820 MWh (November 2007). The highest monthly
generation during any year since 1967 occurred in July 1997 with
377,870 MWh.
Hydropower generation is highest during the winter heating season
(December to mid-February) and in the summer when air-conditioning
systems are used (mid-June to early September) (Figure 2-13). Almost
all of the power generated at Garrison Dam is supplied to the grid;
less than 1 percent of the total power produced is used for on-site
operations (Jody Farhat, personal communications, November 14, 2008).
2.3.2. Oahe Dam and Lake Oahe
The primary water management functions of Oahe Dam and Lake Oahe
are similar to the functions of Garrison Dam and Lake Sakakawea, as
defined in the Master Water Control manual as follows (USACE, 2006, p.
VII-3):
``(1) To capture plains snowmelt and localized rainfall runoffs
from the large drainage area between Garrison and Oahe Dams that are
then metered out at controlled release rates to meet System
requirements, while reducing flood damages in the Oahe Dam to Big Bend
reach, especially in the urban Pierre and Fort Pierre areas;
``(2) To serve as a primary storage location for water accumulated
in the System from reduced System releases due to major downstream
flood control regulation, thus helping to alleviate large reservoir
level increases in Big Bend, Fort Randall, and Gavins Point; and
``(3) To provide the extra water needed to meet project purposes
that draft storage during low-water years, particularly downstream
water supply and navigation.
``In addition, hourly and daily releases from Big Bend and Oahe
Dams fluctuate widely to meet varying power loads. Over the long term,
their release rates are geared to back up navigation releases from Fort
Randall and Gavins Point Dams in addition to providing storage space to
permit a smooth transition in the scheduled annual fall drawdown of
Fort Randall. Big Bend, with less than 2 million acre-feet of storage,
is primarily used for hydropower production, so releases from Oahe are
generally passed directly through Big Bend.''
The Carryover and Multiple Use space (1,607.5 ft msl) of Lake Oahe
was filled in 1967. This space remained generally filled with the
exception of the periods between 1987 and 1993, and from 2000 to the
present (Table 2-3; Figures 2-14 and 2-15). Monthly variability was
lowest during winter months (Figure 2-16). The variability in the
elevations in Lake Oahe was very similar to the variability in Lake
Sakakawea (Figures 2-7 to 2-9), as expected given the primary water
management functions of Lake Oahe (stated above). Outflows are
typically through the power facilities.
The highest monthly elevations occurred in June 1995, June 1996,
and July 1997 with elevations of 1,618 feet msl. In 2007, the maximum
monthly lake elevation was 35 feet lower at 1,583 feet msl (June 2007).
TABLE 2-2.--GROSS ENERGY PRODUCTION IN GARRISON RESERVOIR, JUNE 1967 TO SEPTEMBER 2008 (IN MWh)
[Retrieved on 8-October-2008]
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
MONTH FULL YEAR (Jan-Dec) Colder
YEAR ------------------------------------------------------------------------------------------------------------------------------------------------------------------ Months
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MIN MAX TOTAL MEAN (Dec-Apr)
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1967................................... ........ ........ ........ ........ ........ 232,818 295,092 336,767 237,050 275,633 237,942 241,156 232,818 336,767 .......... ........ 172,681 252,539 222,647
1968................................... 252,539 250,001 172,681 196,858 181,466 149,118 156,431 189,139 212,389 290,561 220,158 234,317 149,118 290,561 2,505,658 208,805 226,709 274,214 255,821
1969................................... 270,694 273,173 274,214 226,709 220,131 163,022 257,475 282,114 238,412 234,153 234,215 270,807 163,022 282,114 2,945,119 245,427 184,253 270,807 227,939
1970................................... 238,768 229,732 184,253 216,135 249,277 249,694 253,971 260,164 202,972 254,324 255,847 226,249 184,253 260,164 2,821,386 235,116 226,249 310,917 263,027
1971................................... 278,471 237,686 261,810 310,917 344,378 316,965 332,812 252,987 219,089 227,357 231,432 227,571 219,089 344,378 3,241,475 270,123 227,571 339,180 265,772
1972................................... 264,805 246,236 251,070 339,180 355,277 337,281 259,622 223,343 193,055 207,270 207,332 216,580 193,055 355,277 3,101,051 258,421 184,710 252,601 220,806
1973................................... 252,601 214,626 235,511 184,710 162,558 175,566 195,675 200,477 182,992 184,094 183,062 216,226 162,558 252,601 2,388,098 199,008 173,132 239,337 215,725
1974................................... 239,337 220,615 229,313 173,132 193,606 216,058 250,441 265,274 217,902 274,602 224,294 229,846 173,132 274,602 2,734,420 227,868 159,040 229,846 209,749
1975................................... 202,670 228,625 228,566 159,040 300,368 344,928 327,106 346,401 344,051 307,207 301,414 259,895 159,040 346,401 3,350,271 279,189 238,366 280,298 257,492
1976................................... 238,366 267,342 241,560 280,298 293,607 337,657 347,855 297,624 241,298 240,857 267,802 222,627 222,627 347,855 3,276,893 273,074 145,158 261,495 208,742
1977................................... 261,495 226,827 187,604 145,158 146,577 140,361 161,710 149,503 130,351 116,836 144,514 188,750 116,836 261,495 1,999,686 166,641 152,426 238,901 194,929
1978................................... 238,901 223,758 170,809 152,426 147,911 282,902 365,976 359,461 297,607 294,386 288,538 216,800 147,911 365,976 3,039,475 253,290 216,800 273,286 244,758
1979................................... 273,286 242,247 243,472 247,986 337,281 326,261 248,273 200,522 161,316 143,923 131,469 185,069 131,469 337,281 2,741,105 228,425 180,241 250,217 214,344
1980................................... 211,978 250,217 244,215 180,241 171,693 187,355 242,163 220,382 195,389 205,592 215,010 192,581 171,693 250,217 2,516,816 209,735 144,434 223,298 196,664
1981................................... 223,298 221,708 201,301 144,434 157,530 220,945 258,497 211,709 169,211 137,018 134,494 174,483 134,494 258,497 2,254,628 187,886 150,534 246,046 206,238
1982................................... 229,612 246,046 230,513 150,534 220,269 205,686 241,775 196,792 165,964 182,936 273,082 214,505 150,534 273,082 2,557,714 213,143 195,282 265,769 226,011
1983................................... 195,282 252,410 265,769 202091 158451 166,381 171,991 255,878 213,868 133,385 156,472 209,450 133,385 265,769 2,381,428 198,452 149,491 255,688 205,239
1984................................... 255,688 234,352 177,212 149,491 133,458 133,898 219,728 268,821 241,132 229,359 235,378 208,485 133,458 268,821 2,487,002 207,250 160,436 252,369 207,842
1985................................... 252,369 240,712 177,209 160,436 177,001 188,864 185,625 173,756 156,144 127,688 139,786 199,184 127,688 252,369 2,178,774 181,565 170,761 235,321 209,425
1986................................... 235,321 212,537 229,322 170,761 99,653 141,125 188,609 235,182 184,242 214,922 226,168 193,816 99,653 235,321 2,331,658 194,305 97,604 231,899 181,663
1987................................... 226,673 231,899 158,323 97,604 148,884 169,561 180,083 178,711 154,063 127,735 122,734 191,642 97,604 231,899 1,987,912 165,659 159,051 223,301 189,689
1988................................... 198,547 223,301 175,902 159,051 168,085 166,187 172,799 160,599 117,128 95,739 94,058 159,654 94,058 223,301 1,891,050 157,588 130,908 170,372 152,551
1989................................... 163,976 170,372 137,847 130,908 182,384 192,195 198,356 190,547 108,517 95,189 158,685 170,366 95,189 198,356 1,899,342 158,279 128,636 206,707 160,120
1990................................... 206,707 148,555 128,636 146,336 164,180 168,175 172,163 158,428 92,532 88,832 96,474 148,656 88,832 206,707 1,719,674 143,306 103,663 173,156 145,017
1991................................... 173,156 159,305 103,663 140,304 163,980 161,695 174,731 173,966 118,687 116,791 122,517 166,840 103,663 174,731 1,775,635 147,970 108,911 196,593 154,783
1992................................... 196,593 164,598 108,911 136,972 169,802 164,615 172,671 160,192 115,239 86,884 84,653 156,621 84,653 196,593 1,717,751 143,146 85,072 159,708 119,047
1993................................... 159,708 104,673 89,163 85,072 134,907 138,487 137,753 149,864 104,769 96,345 102,339 130,855 85,072 159,708 1,433,935 119,495 111,526 136,453 122,297
1994................................... 136,453 117,532 115,117 111,526 231,975 216,358 190,774 184,486 150,159 112,592 128,289 180,847 111,526 231,975 1,876,108 156,342 111,981 199,766 160,562
1995................................... 199,766 175,462 134,753 111,981 119,587 105,419 137,043 300,487 347,671 353,293 294,565 197,713 105,419 353,293 2,477,740 206,478 182,434 250,196 208,567
1996................................... 221,226 191,266 182,434 250,196 290,399 335,550 367,096 359,879 331,570 261,562 197,127 185,159 182,434 367,096 3,173,464 264,455 153,772 218,714 179,118
1997................................... 218,714 183,318 153,772 154,629 297,147 360,731 377,870 362,492 359,527 356,377 316,385 199,143 153,772 377,870 3,340,105 278,342 170,373 199,143 187,931
1998................................... 197,614 198,563 173,961 170,373 214,778 223,976 219,973 220,021 185,343 146,834 175,793 190,242 146,834 223,976 2,317,471 193,123 190,242 235,541 215,544
1999................................... 221,959 217,155 212,825 235,541 236,204 265,232 267,076 260,022 210,046 171,329 154,754 177,371 154,754 267,076 2,629,514 219,126 163,472 200,649 179,326
2000................................... 187,146 200,649 163,472 167,992 197,165 209,323 210,979 204,901 151,966 122,592 174,651 153,161 122,592 210,979 2,143,997 178,666 103,331 159,385 131,686
2001................................... 159,385 129,011 113,542 103,331 105,408 116,976 121,032 122,385 94,213 85,351 85,865 111,259 85,351 159,385 1,347,758 112,313 86,132 111,452 101,800
2002................................... 111,452 100,760 99,396 86,132 106,810 172,552 179,593 180,714 144,581 118,357 146,246 162,429 86,132 180,714 1,609,022 134,085 142,549 164,934 154,186
2003................................... 150,925 164,934 142,549 150,091 155,550 174,755 183,761 177,311 135,844 86,510 93,167 130,288 86,510 183,761 1,745,685 145,474 130,288 171,953 144,374
2004................................... 156,136 171,953 132,585 130,906 126,761 140,007 145,470 138,970 116,618 92,022 97,700 119,484 92,022 171,953 1,568,612 130,718 90,236 129,719 110,276
2005................................... 118,210 90,236 93,733 129,719 125,240 115,245 125,521 127,459 110,058 100,814 103,473 122,061 90,236 129,719 1,361,769 113,481 104,814 140,181 118,134
2006................................... 140,181 109,310 114,305 104,814 122,996 158,479 169,765 176,082 135,781 94,534 99,072 117,784 94,534 176,082 1,543,103 128,592 100,052 121,942 112,050
2007................................... 121,942 108,113 112,359 100,052 104,596 125,814 130,747 129,425 90,900 85,512 82,820 117,329 82,820 130,747 1,309,609 109,134 92,767 117,329 106,900
2008................................... 117,115 110,226 97,062 92,767 98,124 110,098 114,729 119,052 104,899 ........ ........ ........ 92,767 119,052 .......... ........ ......... ........ ........
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- STATISTICS (JANUARY 1968 TO DECEMBER 2007)
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------NUM.................................... 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40
MIN.................................... 111,452 90,236 89,163 85,072 99,653 105,419 121,032 122,385 90,900 85,351 82,820 111,259 82,820 129,719 1,309,609 109,134 85,072 111,452 101,800
MEAN................................... 207,049 196,995 176,341 167,352 190,433 204,135 217,525 217,662 183,565 172,542 175,046 184,404 130,426 251,968 2,293,048 191,087 150,835 215,467 184,154
MAX.................................... 278,471 273,173 274,214 339,180 355,277 360,731 377,870 362,492 359,527 356,377 316,385 270,807 222,627 377,870 3,350,271 279,189 238,366 339,180 265,772
STDEV.................................. 46,092 51,293 54,583 58,839 70,316 73,284 70,593 66,272 72,898 80,590 69,785 39,825 39,164 69,461 609,547 50,796 43,119 54,891 46,665
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 2-10.--Annual total gross energy generation at Garrison Dam
(Source of data: USACE).
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 2-11.--Monthly gross energy generation at Garrison Dam (Source
of data: USACE).
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 2-12.--Gross energy generation at Garrison Dam; monthly mean,
minimum and maximum for each year (Source of data: USACE).
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 2-13.--Monthly gross energy generation at Garrison Dam, relative
to total annual generation Highest mean generation occurred in
December, July, and August (Source of data: USACE).
2.4 Western Area Power Administration (WAPA)
The Western Area Power Administration (WAPA) is an agency of the
Department of Energy (Western). WAPA markets and transmits the power
generated by the dams of the System by law at cost to non-profit
preference power entities. Wholesale electrical power is transmitted
through an integrated 17,000-circuit mile, high-voltage transmission
system across 15 Western States including North Dakota, South Dakota,
Nebraska, Utah, Nevada, California, and portions of Minnesota, Iowa,
Kansas, Colorado New Mexico, Arizona, Texas, Wyoming, and Montana. The
six projects in the System (including Garrison Dam and Oahe Dam)
generated on average 8.3 million MWh per year between fiscal year 1997
and 2007, ranging from 5.0 million MWH in 2007 to 13.9 MWh in 1997.
2.5 Benefits of System's Hydropower Facilities
The hydropower facilities of the System are beneficial to the
region as they provide dependable cost-based energy to meet Western's
share of the annual peak power demands. Energy generated by these
facilities have valuable characteristics that improve the reliability
and efficiency of the electric power supply system, such as efficient
peaking, a rapid rate of unit unloading, and rapid power availability
for emergencies in the power grid (USACE, 2006). However, the
limitations placed upon the power plant detailed above limits the plant
from being an optimally efficient peaking facility. Another benefit is
the fact that the facilities generate clean energy with a minimal
carbon-footprint.
TABLE 2-3.--END-OF-MONTH ELEVATION OF LAKE OAHE, JUNE 1967 TO SEPTEMBER 2008 (IN FEET msl)
[Retrieved on 8-October-2008]
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
MONTH FULL YEAR (Jan-Dec) Colder Months (Dec-Apr)
--------------------------------------------------------------------------------------------------------------------------------------- \1\
YEAR --------------------------
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MIN MAX MEAN MIN MAX MEAN
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1967.......................... ....... ....... ....... ....... ....... 1,598.3 1,599.5 1,601.5 1,602.8 1,604.2 1,606.2 1,606.9 ....... ....... ....... 1,606.9 1,609.0 1,608.4
1968.......................... 1,608.7 1,609.0 1,608.8 1,608.8 1,607.4 1,606.7 1,603.3 1,601.0 1,599.9 1,602.8 1,604.7 1,604.7 1,599.9 1,609.0 1,605.5 1,604.7 1,615.6 1,609.4
1969.......................... 1,605.1 1,608.8 1,612.8 1,615.6 1,615.8 1,613.7 1,614.3 1,610.4 1,607.6 1,606.2 1,606.7 1,607.9 1,605.1 1,615.8 1,610.4 1,605.7 1,608.7 1,607.3
1970.......................... 1,606.5 1,607.6 1,605.7 1,608.7 1,612.5 1,612.8 1,610.0 1,607.5 1,605.1 1,604.9 1,605.9 1,604.5 1,604.5 1,612.8 1,607.6 1,604.5 1,615.5 1,609.6
1971.......................... 1,606.1 1,608.5 1,613.4 1,615.5 1,616.7 1,616.2 1,614.7 1,610.5 1,607.2 1,604.9 1,602.2 1,601.2 1,601.2 1,616.7 1,609.8 1,601.2 1,609.8 1,605.3
1972.......................... 1,602.4 1,603.9 1,609.0 1,609.8 1,614.4 1,615.8 1,614.4 1,610.2 1,606.4 1,602.6 1,601.0 1,599.9 1,599.9 1,615.8 1,607.5 1,599.9 1,608.8 1,604.3
1973.......................... 1,602.3 1,603.1 1,607.3 1,608.8 1,608.5 1,607.8 1,606.1 1,603.4 1,602.4 1,602.2 1,603.8 1,604.4 1,602.2 1,608.8 1,605.0 1,604.4 1,609.2 1,607.1
1974.......................... 1,605.7 1,607.2 1,609.2 1,608.9 1,608.6 1,608.0 1,606.1 1,604.5 1,602.6 1,603.1 1,603.7 1,605.1 1,602.6 1,609.2 1,606.1 1,604.7 1,609.8 1,606.8
1975.......................... 1,604.7 1,606.7 1,607.7 1,609.8 1,612.9 1,614.5 1,616.6 1,617.1 1,613.5 1,608.7 1,604.8 1,605.0 1,604.7 1,617.1 1,610.2 1,604.9 1,606.5 1,605.8
1976.......................... 1,604.9 1,606.5 1,606.2 1,606.5 1,607.5 1,609.0 1,608.1 1,606.7 1,603.9 1,603.5 1,604.0 1,603.9 1,603.5 1,609.0 1,605.9 1,603.9 1,608.2 1,606.3
1977.......................... 1604.6 1607.4 1,608.2 1607.5 1606.3 1605.5 1602.6 1599.0 1596.9 1595.4 1594.5 1594.8 1594.5 1608.2 1601.9 1,594.8 1,614.7 1,603.5
1978.......................... 1,596.9 1,600.7 1,610.3 1,614.7 1,615.7 1,615.4 1,615.0 1,613.4 1,610.4 1,607.0 1,605.6 1,604.6 1,596.9 1,615.7 1,609.1 1,604.6 1,614.3 1,608.4
1979.......................... 1,605.9 1,607.1 1,610.0 1,614.3 1,615.3 1,615.9 1,615.2 1,613.4 1,611.6 1,608.2 1,606.0 1,605.1 1,605.1 1,615.9 1,610.7 1,604.3 1,608.1 1,606.3
1980.......................... 1,604.3 1,606.2 1,607.9 1,608.1 1,605.9 1,605.0 1,603.1 1,600.0 1,598.0 1,597.2 1,596.8 1,598.1 1,596.8 1,608.1 1,602.6 1,597.8 1,602.0 1,599.8
1981.......................... 1,599.7 1,601.4 1,602.0 1,597.8 1,594.7 1,595.0 1,595.5 1,594.2 1,592.6 1,591.1 1,591.6 1,591.4 1,591.1 1,602.0 1,595.6 1,591.4 1,604.9 1,597.7
1982.......................... 1,592.6 1,597.2 1,602.3 1,604.9 1,610.2 1,612.5 1,612.9 1,610.8 1,607.9 1,607.8 1,608.5 1,607.7 1,592.6 1,612.9 1,606.3 1,605.8 1,614.4 1,609.3
1983.......................... 1,605.8 1,607.4 1,611.4 1,614.4 1,616.0 1,615.9 1,615.8 1,613.8 1,612.6 1,609.8 1,607.6 1,605.7 1,605.7 1,616.0 1,611.4 1,605.7 1,613.3 1,609.9
1984.......................... 1,608.4 1,610.7 1,611.4 1,613.3 1,615.6 1,618.3 1,616.8 1,613.8 1,610.2 1,608.9 1,606.7 1,605.2 1,605.2 1,618.3 1,611.6 1,605.2 1,611.0 1,608.2
1985.......................... 1,606.1 1,608.6 1,611.0 1,610.0 1,609.7 1,608.2 1,605.4 1,603.2 1,601.7 1,601.2 1,599.2 1,598.9 1,598.9 1,611.0 1,605.S 1,598.9 1,616.4 1,606.5
1986.......................... 1,601.4 1,603.9 1,611.9 1,616.4 1,617.4 1,617.0 1,615.4 1,612.7 1,610.8 1,609.6 1,608.7 1,605.7 1,601.4 1,617.4 1,610.9 1,604.2 1,614.6 1,608.5
1987.......................... 1,604.2 1,606.1 1,612.1 1,614.6 1,613.7 1,613.3 1,611.6 1,610.1 1,607.8 1,605.7 1,604.0 1,604.5 1,604.0 1,614.6 1,609.0 1,604.0 1,606.7 1,605.4
1988.......................... 1,604.0 1,606.2 1,606.7 1,605.5 1,604.7 1,603.0 1,600.3 1,597.0 1,592.8 1,590.3 1,588.6 1,589.1 1,588.6 1,606.7 1,599.0 1,589.1 1,593.2 1,591.1
1989.......................... 1,589.5 1,591.2 1,593.2 1,592.5 1,590.9 1,589.3 1,587.5 1,584.7 1,583.2 1,581.0 1,583.8 1,583.9 1,581.0 1,593.2 1,587.6 1,583.9 1,590.7 1,588.1
1990.......................... 1,587.8 1,589.5 1,590.7 1,588.8 1,588.1 1,589.2 1,588.2 1,586.1 1,583.5 1,581.2 1,582.2 1,582.2 1,581.2 1,590.7 1,586.5 1,582.2 1,587.9 1,585.3
1991.......................... 1,583.4 1,586.0 1,587.9 1,587.2 1,588.5 1,592.9 1,591.2 1,588.5 1,583.3 1,584.9 1,586.5 1,587.6 1,583.3 1,592.9 1,587.3 1,587.6 1,592.2 1,590.3
1992.......................... 1,589.3 1,591.5 1,592.2 1,591.1 1,590.4 1,589.8 1,590.0 1,590.1 1,591.4 1,591.0 1,591.8 1,591.6 1,589.3 1,592.2 1,590.9 1,591.6 1,597.9 1,594.2
1993.......................... 1,592.2 1,592.7 1,596.4 1,597.9 1,600.2 1,601.9 1,608.0 1,610.4 1,610.7 1,610.3 1,609.8 1,609.5 1,592.2 1,610.7 1,603.3 1,607.6 1,611.6 1,609.5
1994.......................... 1,608.2 1,607.6 1,611.6 1,610.6 1,610.6 1,610.2 1,610.0 1,608.1 1,606.3 1,605.2 1,603.8 1,603.7 1,603.7 1,611.6 1,608.0 1,603.7 1,610.6 1,606.8
1995.......................... 1,604.0 1,607.0 1,608.6 1,610.6 1,616.7 1,618.4 1,616.2 1,613.3 1,612.3 1,611.1 1,609.5 1,608.2 1,604.0 1,618.4 1,611.3 1,607.9 1,613.1 1,610.6
1996.......................... 1,607.9 1,611.1 1,612.8 1,613.1 1,616.9 1,618.5 1,617.5 1,616.0 1,615.3 1,613.5 1,609.3 1,607.5 1,607.5 1,618.5 1,613.3 1,607.5 1,617.9 1,612.2
1997.......................... 1,607.7 1,609.9 1,617.9 1,617.9 1,617.6 1,617.8 1,618.3 1,617.1 1,616.5 1,615.3 1,612.4 1,609.8 1,607.7 1,618.3 1,614.9 1,607.7 1,609.8 1,608.8
1998.......................... 1,607.7 1,608.4 1,608.2 1,609.7 1,609.7 1,611.5 1,612.2 1,612.2 1,610.6 1,609.5 1,609.3 1,607.4 1,607.4 1,612.2 1,609.7 1,606.4 1,611.1 1,608.4
1999.......................... 1,606.4 1,607.9 1,609.2 1,611.1 1,615.6 1,617.0 1,616.9 1,617.0 1,614.7 1,610.9 1,607.4 1,606.9 1,606.4 1,617.0 1,611.8 1,605.4 1,607.3 1,606.6
2000.......................... 1,605.4 1,606.4 1,607.0 1,607.3 1,607.3 1,606.2 1,604.8 1,602.5 1,599.5 1,598.3 1,597.3 1,597.1 1,597.1 1,607.3 1,603.3 1,597.1 1,604.8 1,600.0
2001.......................... 1,597.7 1,598.4 1,601.9 1,604.8 1,607.7 1,608.8 1,608.7 1,605.8 1,603.0 1,601.2 1,599.4 1,598.5 1,597.7 1,608.8 1,603.0 1,596.2 1,598.9 1,598.1
2002.......................... 1,598.6 1,598.9 1,598.2 1,596.2 1,595.3 1,592.7 1,590.8 1,588.1 1,586.4 1,585.1 1,583.4 1,584.8 1,583.4 1,598.9 1,591.5 1,584.8 1,588.2 1,586.6
2003.......................... 1,585.3 1,587.2 1,588.2 1,587.5 1,588.7 1,587.4 1,586.5 1,584.4 1,581.0 1,578.2 1,576.7 1,576.9 1,576.7 1,588.7 1,584.0 1,576.9 1,582.1 1,579.5
2004.......................... 1,577.6 1,579.2 1,582.1 1,581.6 1,578.4 1,576.8 1,574.3 1,572.1 1,573.2 1,574.8 1,576.0 1,575.8 1,572.1 1,582.1 1,576.8 1,574.4 1,576.2 1,575.3
2005.......................... 1,575.2 1,576.2 1,574.4 1,574.7 1,576.5 1,577.6 1,576.4 1,573.1 1,572.9 1,573.9 1,575.6 1,575.3 1,572.9 1,577.6 1,575.2 1,575.3 1,577.6 1,576.8
2006.......................... 1,576.8 1,577.6 1,576.7 1,577.4 1,577.0 1,575.8 1,573.4 1,570.3 1,571.4 1,572.6 1,573.2 1,572.8 1,570.3 1,577.6 1,574.6 1,572.3 1,577.7 1,574.3
2007.......................... 1,572.9 1,572.3 1,575.8 1,577.7 1,580.5 1,582.8 1,581.4 1,580.1 1,580.9 1,580.8 1,582.3 1,582.2 1,572.3 1,582.8 1,579.1 1,581.8 1,583.2 1,582.5
2008.......................... 1,582.3 1,581.8 1,583.2 1,582.8 1,584.7 1,592.6 1,593.9 1,592.4 1,593.1 ....... ....... ....... ....... ....... ....... ....... ....... .......
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ STATISTICS (JANUARY 1968 TO DECEMBER 2007)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------NUM........................... 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40
MIN........................... 1,572.9 1,572.3 1,574.4 1,574.7 1,576.5 1,575.8 1,573.4 1,570.3 1,571.4 1,572.6 1,573.2 1,572.8 1,570.3 1,577.6 1,574.6 1,572.3 1,576.2 1,574.3
MEAN.......................... 1,598.8 1,600.6 1,603.0 1,603.8 1,604.7 1,604.9 1,603.9 1,601.8 1,600.0 1,598.7 1,598.1 1,597.7 1,595.3 1,606.5 1,601.3 1,597.3 1,603.6 1,600.3
MAX........................... 1,608.7 1,611.1 1,617.9 1,617.9 1,617.6 1,618.5 1,618.3 1,617.1 1,616.5 1,615.3 1,612.4 1,609.8 1,607.7 1,618.5 1,614.9 1,607.9 1,617.9 1,612.2
STDEV......................... 10.4 10.6 11.3 12.0 12.6 12.8 13.2 13.4 12.9 12.3 11.4 11.0 11.3 12.2 11.6 10.8 12.1 11.1
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Rows include Jan to Apr of following year.
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 2-14.--End-of month pool elevations in Lake Oahe between 1967
and the present (Source of data: USACE).
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 2-15.--Annual end-of month pool elevations in Lake Oahe; monthly
mean, minimum and maximum for each year (Source of data: USACE).
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 2-16.--Annual end-of month pool elevations in Lake Oahe; monthly
mean, minimum and maximum in winter only (Dec-Feb) for each year
(Source of data: USACE).
Costs of power generation by the System's facilities are very low
compared to the costs of other types of energy generation facilities
(coal, gas, oil, nuclear). WAPA conducts rate studies intermittently to
adjust the rates for the power generated by the hydropower dams in the
System. Rates have gradually increased from approximately $5/MWh in
1973 to $18/MWh in 2007. Based on these rates, the revenue from net
energy generated at Garrison Dam has increased from approximately $12
million in 1973 to $24 million in 2007 (Figure 2-17). Highest revenues
were achieved in 1996 as a result of high rainfall in the watershed
which led to higher energy generation. Highest demand for hydropower
exists in summer and in winter; higher energy generation in these
months consequently results in higher revenues (Figure 2-18).
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 2-17.--Annual revenues for net energy generated by Garrison Dam
between fiscal year 1973 and fiscal year 2007 (Sources of input data:
USACE).
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 2-18.--Mean monthly revenue generated by Garrison Dam for fiscal
year 2005 through fiscal year 2007 (Source of input data: USACE).
3.0 SILTATION IMPACTS ON HYDROPOWER OPERATIONS
Potential impacts from siltation in the Missouri River on
hydropower operations in North Dakota consist of the following:
--Loss of storage in Lake Sakakawea
--Entrainment of sediment into the turbines at Garrison Dam
--Reduced releases at Garrison Dam in winter due to flooding risk
from sediment aggradation
3.1 Loss of Storage in Lake Sakakawea
3.1.1. Sediment Sources
Sediment enters the reservoir primarily via the Missouri River and
its tributaries. Another source is shoreline erosion. Due to the size
of Lake Sakakawea, nearly all of the sediment that enters the reservoir
remains there as sediment deposits. The USGS (1995) considers the
trapping efficiency 100 percent, with only negligible amounts of
suspended sediment being transported beyond Garrison Dam.
The drainage area of Lake Sakakawea is 181,400 square miles.
Excluding the drainage area of the Fort Peck Lake, which traps the
sediment of its own watershed, the drainage area for Lake Sakakawea is
123,900 square miles.
The largest point sources for sediment to Lake Sakakawea are the
Missouri River and especially the Yellowstone River, a tributary to the
Missouri River (Figure 2-3). The headwaters of the 678-mile long
Yellowstone River are in Wyoming and Montana. The lower 18 miles of the
Yellowstone River are within North Dakota. The Yellowstone River joins
with the Missouri River at RM 1581. Downstream from the confluence, the
Missouri River is free-flowing until up to the headwaters of Lake
Sakakawea. The free-flowing stretch of the Missouri River depends upon
Lake Sakakawea's elevation; the length of this free-flowing stretch may
be as little as 15 miles (e.g., in year 1997) to as many as 50 miles
(e.g., in year 1991) (NDGFD, 2002). Sediment from mainly the Missouri
River and the Yellowstone River has buried the old river channel
downstream of approximately RM 1535.
The Yellowstone River is largely unregulated, with only two dams in
the headwaters (Yellowtail Dam and Boysen Dam; Figure 2-3). The mean
annual flow of the Yellowstone River at its lowest gaging station (at
Sidney, Montana) was determined as 12,250 cfs, with a maximum
instantaneous flow estimated at 159,000 cfs in June 1921 (NDGFD, 2002).
Some of the highest stages in the river were caused by ice dams. The
construction of upstream water depletion projects have reduced flows in
the Yellowstone River by approximately 24 percent from historical
levels. In comparison, annual flows of the Missouri River at its lowest
gaging station above the confluence with the Yellowstone River, located
in Culbertson, Montana, have averaged 10,270 cfs. The peak flow in the
Missouri River after closure of Fort Peck Dam was 78,200 cfs on March
1943.
The mean grain size of the suspended sediment in the Missouri River
at Culbertson, Montana, near the border with North Dakota, was measured
as 45 percent sand, 50 percent silt, and 5 percent clay (USACE, 1978,
as listed in Wuebben and Gagnon, 1995). The corresponding grain sizes
in the Yellowstone River at Sidney, Montana, were 35 percent, 60
percent and 5 percent, respectively. The mean grain size (D50) of the
bed material was 0.28 mm in the Missouri River at Culbertson, and 0.25
mm in the Yellowstone River at Sidney. Both mean grain sizes fall into
the ``medium sand'' category which has a size range of 0.25 to 0.50 mm.
The USACE (1978) estimated the sediment load from the Missouri
River at Culbertson, Montana, with 13.5 million tons/year. A much
greater load (41.5 million tons/year) was estimated to be supplied to
Lake Sakakawea by the Yellowstone River at Sidney near the confluence
with the Missouri River. According to preliminary studies by the USGS
(as mentioned in Wuebben and Gagnon, 1995), these loads (total of 55
million tons/year) may have been overestimated by 30 percent.
Sediment contributed by the Missouri River includes sediment that
is eroded from the river's bank and bottom, downstream of the Fort Peck
dam.
The USACE (1993a) estimated that the gross storage loss for all of
Lake Sakakawea since closure of the dam in 1953 and the survey date in
1988 was 907,000 acre-feet or 25,900 acre feet/year. Using a bulk
density of 1.4 g/cm3, based on values provided by Geiger (1963) for
sand and silt, this volume translates into a sediment supply of 45
million tons/year. This volume is similar to the volume discussed above
in Wuebben and Gagnon (1995), after allowing for a 30 percent reduction
as suggested.
Additional riverine sediment sources to Lake Sakakawea are numerous
small tributaries such as the Little Missouri River, and shoreline
erosion in the lake. Shoreline erosion occurs primarily as a result of
waves acting on bluffs and other erodible topographic features. The
likelihood of shoreline erosion is highest during periods of high water
elevations in the reservoir. The relative contribution of shoreline
erosion to the total sediment load entering Lake Sakakawea is
considered to be very small, however (John Remus, pers. communication,
November 21, 2008).
3.1.2. Sediment Deposition in Lake Sakakawea
Lake Sakakawea extends close to the border of North Dakota with
Montana. Sediment initially accumulated in the lower elevation zones
during the filling of Garrison Lake. In 1993, the USACE estimated that
3.5 percent of the capacity in the Permanent Pool was lost.
Since the pool was filled, sediments carried by the Missouri River
settle out in the calmer headwaters of Lake Sakakawea. This deposition
has resulted in a progressive loss of the channel capacity as well as
in an upward shift of the stage-discharge relationship. Already the
upper reach of the lake is silted in heavily. New sediment islands form
continuously over time and gradually migrate downgradient (Figure 3-1).
However, the aggradation is largely confined to the upper reaches of
the reservoir (Figures 3-2 to 3-4). This is also reflected in USACE
(1993a):
``. . . the location of the sediment deposits vary significantly
longitudinally throughout the reservoirs [of the System]. The majority
of the sediment begins to settle out 10 to 15 miles downstream from the
upstream end of the pools, and is concentrated within a 30-mile reach
downstream from this point. Sediment deposits of any significant
quantity have not been observed in the vicinity of the dams and/or
powerhouses at any of the six dams [of the System]. Most of the
sediment that presently exists in the lower elevation zones of the
pools was deposited during the reservoir filling period, and little
change has been noted . . . since the projects were first filled.'' (p.
6)
As stated above, the USACE (1993a) estimated that the gross storage
loss for all of Lake Sakakawea since closure of the dam in 1953 and the
survey date in 1988 was 907,000 acre-feet or 25,900 acre-feet/year. In
the 20 years since that time, sedimentation has continued in the upper
reaches of Lake Sakakawea. Assuming that the sediment accumulation rate
from 1993 also applies for the period since the 1988 survey, an
additional 518,000 acre-feet would have been deposited in Lake
Sakakawea by year 2008. Accordingly, the total sediment load that has
been deposited in the reservoir between 1953 and 2008 (55-year time
span) is 1,425,000 acre-feet. This volume translates to a loss in
storage volume of 6 percent of Lake Sakakawea at the Maximum Operating
Pool level (1,854 feet msl), or 0.11 percent per year.
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 3-1.--Upper Lake Sakakawea area, showing sediment aggradation.
(The aerial photo is from June 23, 2003 (Source: Google Earth).
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 3-2.--Changes in thalweg elevations in Lake Sakakawea, 1956 and
1987 (USACE, 1993a).
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 3-3.--Changes in average bed elevations in Lake Sakakawea, 1956
and 1987 (USACE, 1993a).
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 3-4.--Changes in volume in Lake Sakakawea between 1956 and 1988
(USACE, 1993a).
The actual loss might be slightly lower as a result of increased
equilibration of the Missouri River channel between Fort Peck and the
upper Lake Sakakawea, resulting in gradually decreasing erosion rates
over time.
Using a uniform sediment aggradation rate, these values suggest
that Lake Sakakawea would be filled completely with sediment 900 years
after construction of the Garrison Dam. This value is only first-order
approximation as it does not consider variables such as sediment
trapping efficiency, climate variability over time, or potential
sediment contributions from the watershed of Fort Peck Lake (which may
be filled before Lake Sakakawea):
--Sediment Trapping Efficiency.--This first-order calculation assumes
a continuous trapping efficiency of 100 percent. In reality,
however, the trapping efficiency will gradually decrease toward
the end of the life expectancy for the reservoir, and sediment
will start to be transported passed Garrison Dam.
--Climate Variability Over Time.--Nine hundred years is a long time
during which the regional climate is expected to vary over the
short and long term. Decreasing precipitation in the Lake
Sakakawea watershed will result in less sediment erosion and
hence a longer life expectancy of the reservoir, and vice
versa.
--Sediment Contributions From the Watershed of Fort Peck Lake.--Like
Lake Sakakawea, Fort Peck Lake most likely captures nearly all
of the sediment of its watershed. When the lake eventually
fills with sediment, this sediment will bypass Fort Peck Dam
and also enter Lake Sakakawea. Comparisons between 1938 and
1986 lake bed data demonstrate that there was a storage loss of
869,000 acre-feet, or 18,100 acre-feet/year (USACE, 1993a).
Assuming the same loss rate for years 1987 to 2008, an added
398,000 acre-feet would have been lost. Therefore, the total
loss to-date since construction would be 1,267,000 acre-feet.
The volume represents a 6.8 percent loss of the gross storage
volume of Fort Peck Lake of 18,688,000 acre-feet since
construction 70 years ago (i.e., 0.10 percent per year). This
loss rate is very similar to the loss rate of Lake Sakakawea
(0.11 percent per year), suggesting a similar first-order life
expectancy of 900 years. Based on these data, sediment from the
Fort Peck Lake watershed will not reach Lake Sakakawea for many
centuries.
3.2 Entrainment of Sediment into the Turbines at Garrison Dam
Impacts to the hydropower operation will start to occur well before
Lake Sakakawea has filled with sediment. However, with an annual loss
of storage capacity by 0.11 percent, and most of the deposition
occurring in the upper reaches of the reservoir, impacts to the intakes
to the hydropower facility are not expected for a long time. As a
result, the USACE does not have any specific sediment management
methods or sediment control facilities at their hydroelectric
facilities at this time (Bill Mulligan, personal communication;
November 13, 2008).
Eventually, impacts will consist of clogging of the intake and
abrasion of the turbine blades by coarser sediment grains. The start
date for these impacts depends on parameters such as grain size, water
elevation in the reservoir over time, frequency of drought conditions
(which will bring sediment further into the lake), geometry of the
lake, flows velocities in front of the intake to the turbines, and
elevation of the intake in the water column relative to the elevation
of the reservoir. Based on the existing information, including USACE
(1993a), most of the sediment carried into the lake by the Missouri
River remains as delta deposits in the headwaters of the lake. Thus,
only the finest particles that can remain in suspension for a long time
are transported further downstream at present. As a rough first-order
estimate, we anticipate that effects on the turbines from sediment
deposition in the reservoir will be negligible for at least the next
200 years. However, a more detailed assessment must be performed if a
more accurate estimate is desired.
3.3 Reduced Releases at Garrison Dam in Winter due to Flooding Risk
Siltation in the reach between Garrison Dam and Lake Oahe has
resulted in increased risk of flooding in the downstream reach between
the dam and the headwater of Oahe Lake. The Missouri River typically
freezes in December (``ice-in''; ``freeze-up''). It remains frozen in
January and February, and starts to thaw in March and April (``ice-
out''; ``break-up'') (Jody Farhat, pers. communication, November 14,
2008). A large consideration in flow releases are ice dams (Figure 3-
5). Ice dams can form during freeze-up as well as during break-up
(FEMA, 2005). Ice-in starts at the headwaters of Lake Oahe, and moves
upstream toward Garrison Dam. Break-up ice dams normally occur in late
winter or early spring during the melting period. These break-up ice
dams are most common downstream of the confluence between the Missouri
River and the Heart River (RM 1311) (Figure 3-6). According to FEMA
(2005), these ice dams form mostly because of high flows in the Heart
River during snowmelt or spring rains while the Missouri River is still
covered with ice. Siltation in the river indirectly worsens such
flooding, as the ice sheet in the Missouri River is at a higher
elevation than it would be without aggradation.
In order to minimize the flooding risk, specifically in the
Bismarck/Mandan area, the USACE releases water from Lake Sakakawea in
the following manner:
--Ice-in (December).--The USACE releases water at a reduced rate
while the ice is forming on the river. The gradually forming
ice creates a ``conduit'' for the released water underneath it.
Initially the ice surfaces are rough and ``chunky'', resulting
in a higher risk of flooding. As a result, release rates have
been reduced to as low as 16,000 cfs in past years as the ice
sheet build-up advances upstream from the headwaters of Lake
Oahe.
--January-December.--After the ice has formed on the river, it is
smoothed on its underside by the flowing water, allowing for an
increase in the release rate at Garrison Dam. The rate is set
in a manner that prevents flow over the ice or the breakup of
the ice which could cause ice dams. As specified in the Master
Water Control Manual, release rates are not normally scheduled
above 20,000 cfs in December (USACE, 2006). However, based on
experience, water release rates of 27,000 cfs are possible.
This maximum winter release rate is a reduction of the original
capacity of 35,000 cfs, as a result of aggradation of the river
in the headwaters of Lake Oahe.
--Ice-out (April-March).--The breaking up of the ice presents a risk
to flooding as the moving ice can cause ice dams that block the
flow of water. In addition, rainfall events may result in high
discharges from the tributaries to the Missouri River in the
reach between Garrison Dam and Lake Oahe. These tributary
discharges are often coupled with melting snow from the
watershed. The two largest tributaries are the Heart River and
Knife River. Planned winter flow releases at Garrison Dam
consider flows in these tributaries.
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 3-5.--Longitudinal profile of typical break-up ice jam (Wuebben
and Gagnon, 1995).
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 3-6.--Sediment aggradation along the Missouri River between the
cities of Bismarck and Mandan, and the headwaters of Lake Oahe (Source:
Google Earth).
3.3.1. Flows
The mean annual outflow from Lake Sakakawea between 1967 (2 years
after the reservoir was filled) and 2007 was 15.6 million acre-feet
(Table 3-1), which translates into a mean daily flow rate of 21.5
million cfs (Table 3-2). The annual outflow ranged from a minimum of
9.6 million acre-feet in both 1993 and 2001, to a maximum of 25.2
million acre-feet in 1997 (Figure 3-7). Releases from recent years were
close to the minimum due to a drought in the upper Missouri watershed.
Most of the inflow to Lake Oahe comes from water releases at
Garrison Dam. A gaging station is maintained along the Missouri River
at Bismarck (USGS Station 06342500), operated in cooperation with the
USACE. Discharge data at Bismarck reflect the gradual filling of Lake
Sakakawea until the late 1960s (Figures 3-8 and 3-9; Table 3-3).
Thereafter, the discharge rate in the Missouri River gradually
decreased until 1995, as also observed in power generation records and
Garrison Dam release flows. Discharge rates in 1996 and 1997 were very
high due to high runoff in the Upper Missouri River watershed. The
discharge rates decreased in the subsequent years to their currently
lowest level since the Lake Sakakawea was closed (Figure 2-7). The
decrease in flow over the 20 year period between 1968 and 2007 was on
average 50 percent less (Figure 3-10).
As expected, the discharge data between Bismarck (USGS data) and
Garrison Dam (USACE data) coincide well (Figure 3-11). Peak discharges
were slightly higher at Bismarck due to tributary runoff downstream of
Garrison Dam (Figure 3-12). In general, the flow at Bismarck was 8.3
percent \2\ higher compared to release flows at Garrison Dam between
1967 and 2007 (Figure 3-13). This percentage was higher (13.3 percent)
during the ice-out period (March-April), presumably due to snow-melting
in the watershed downstream of Garrison Dam. In specific years, the
flow at Bismarck was higher by as much as 45 percent compared to
release flows at Garrison Dam, which underscores the importance of
managing releases at Garrison Dam to prevent flooding in Bismarck and
Mandan (Figure 3-14).
---------------------------------------------------------------------------
\2\ The USGS gaging station is located upstream in Bismarck. The
Heart River and Apple Creek enter the Missouri River downstream of the
USGS gage. Their mean annual discharge rate is 267 cfs and 45 cfs,
respectively. Thus, these two streams contribute an additional 1.3
percent to the flow of the Missouri River, before the Missouri River
enters Lake Oahe.
---------------------------------------------------------------------------
The annual runoff peak typically occurs in June. The highest
monthly releases occur in July and August (Figure 3-15). The lowest
releases occur during the fall (October and November).
A rating curve at the Bismarck gaging station indicates that there
have been major changes in the stage at this location for flows
exceeding 30,000 cfs. Such flows caused an upward trend of 1 to 2 feet
(Figure 3-16). This increase has caused flooding in the winter in some
of the lower lying housing areas near Bismarck (USACE, 2004c).
According to Mr. Ronald Sando (personal communication November 12,
2008), flooding can occur in Bismarck, south of the Bismarck
Expressway. There has also been flooding in the past in the city of
Mandan along the western bank of the Missouri River.
3.3.2. Sedimentation
The headwaters of Lake Oahe reach almost up to the city of
Bismarck. Sediment deposition has occurred in the headwaters of Lake
Oahe, just as it has in the headwaters of Lake Sakakawea (USACE,
1993b). The highest aggradation of sediment occurred in an area
approximately 10 miles to the south of Bismarck (Berger, 2008). The
sediment delta that formed in Lake Oahe has affected the river's flood
stage in Bismarck and Mandan. At construction, the open-water channel
capacity for a stage of 13 feet was 90,000 cfs (USACE, 2006). In 1975,
just 20 years later, this capacity had been reduced to 50,000 cfs.
Releases at Garrison Dam result in erosion of sediment just
downstream of the dam (USGS, 1995; Biedenharn et al., 2001). The river
stabilizes further downstream as erosion of sediment is balanced by
sediment resupplied from upstream sources. As flow velocities decrease,
the carrying capacity of the river decreases as well. Sediments, both
carried in suspension and as bedload, eventually settle out resulting
in aggradation of the river. A study of the sedimentation from 1958 to
1985 was conducted by the USACE from RM 1390 (Garrison Dam) to RM 1336
(20 miles north of Bismarck) (USACE, 1993c). The study found that the
thalweg and average bed elevations had decreased at most locations
(Table 3-4). The widths of the channel varied. Tailwater elevations at
Garrison Dam had decreased by approximately 7 feet between 1956 and
2003 (USACE, 2004c; Figure 3-17). Erosion in the Missouri River
downstream of Garrison Dam was also shown from investigations along 21
transects by the USGS conducted between Garrison Dam and Lake Oahe
between 1988 and 1991 (USGS, 1995).
The USGS (1995) also observed erosion along transects located in
Bismarck and 6 miles to the south of Bismarck. This erosion was likely
the result of degradation of sediment that had previously been
deposited in the headwater of Lake Oahe. The elevations in Lake Oahe
were lower during the study period (1988 to 1991) than during earlier
years (Figure 2-14). However, elevations have fluctuated since then
with higher elevations in the mid-1990s and again low elevations in
recent years due to drought in the watershed. Bruce Engelhardt also
stated that sedimentation in the Missouri River occurs at times in the
Bismarck area (personal communication, November 13, 2008).
It is expected that the river will continue to erode sediment in
the upper Garrison Reach. Erosion will continue from degradation as
well as from meandering of the channel, although these processes may
gradually decrease over time. Williams and Wolman (1984, as reported in
USGS [1995]) estimated that 95 percent equilibrium would be reached
within 2 to 90 years after completion of a dam, based on a study of 21
dams constructed on alluvial rivers, mostly in the semiarid western
United States. Site-specific data for this reach of the Missouri River
were not located, however, in order to narrow down this wide range.
In urban areas such as Bismarck and Mandan, the river channel has
no room to widen without affecting properties. Therefore, aggradation
within the river at this location results in an increased risk of
flooding and the loss of property. Potential buyouts due to flooding
concerns in the Bismarck-Mandan area are estimated at over $100 million
(Remus, 2008). The impact of flooding is estimated to be greatest
between RM 1300 and 1316, i.e., in downtown Bismarck and Mandan (FEMA,
2005). Flooding also occurs outside of urbanized areas, affecting
cropland and causing soil erosion. Since flooding from ice dams occurs
in winter, there are no crops that could be damaged, however.
TABLE 3-1.--MONTHLY OUTFLOW FROM LAKE SAKAKAWEA, JUNE 1967 TO SEPTEMBER 2008 (IN 1,000 ACRE-FEET)
[Retrieved on 8-October-2008]
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
MONTH FULL YEAR (Jan-Dec) Colder Months (Dec-Apr) \1\
YEAR -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MIN MAX MEAN TOTAL MIN MAX MEAN TOTAL
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1967................................................ ....... ....... ....... ....... ....... 1,574 1,917 2,210 1,560 1,826 1,594 1,635 ....... ....... ....... ....... 1,176 1,739 1,518 7,588
1968................................................ 1,739 1,717 1,176 1,321 1,224 990 1,006 1,219 1,366 1,897 1,439 1,551 990 1,897 1,387 16,645 1,504 1,881 1,723 8,617
1969................................................ 1,810 1,871 1,881 1,504 1,442 1,044 1,630 1,790 1,522 1,514 1,526 1,815 1,044 1,881 1,612 19,349 1,233 1,815 1,541 7,704
1970................................................ 1,616 1,554 1,233 1,486 1,706 1,642 1,610 1,648 1,293 1,626 1,655 1,474 1,233 1,706 1,545 18,543 1,474 2,066 1,744 8,720
1971................................................ 1,863 1,591 1,726 2,066 2,337 2,071 2,134 1,611 1,386 1,444 1,485 1,467 1,386 2,337 1,765 21,181 1,467 2,232 1,753 8,763
1972................................................ 1,764 1,656 1,644 2,232 2,367 2,214 1,648 1,412 1,214 1,305 1,326 1,401 1,214 2,367 1,682 20,183 1,195 1,645 1,437 7,183
1973................................................ 1,645 1,393 1,549 1,195 1,037 1,104 1,225 1,268 1,167 1,157 1,172 1,401 1,037 1,645 1,276 15,313 1,146 1,604 1,435 7,175
1974................................................ 1,604 1,481 1,543 1,146 1,283 1,404 1,589 1,680 1,378 1,747 1,446 1,500 1,146 1,747 1,483 17,801 1,041 1,578 1,401 7,007
1975................................................ 1,358 1,578 1,530 1,041 1,959 2,388 3,800 3,328 2,216 1,994 1,964 1,716 1,041 3,800 2,073 24,872 1,598 1,894 1,725 8,626
1976................................................ 1,598 1,812 1,606 1,894 2,198 2,230 2,244 1,921 1,545 1,547 1,761 1,464 1,464 2,244 1,818 21,820 957 1,803 1,406 7,030
1977................................................ 1,803 1,552 1,254 957 971 920 1,069 999 866 774 972 1,298 774 1,803 1,120 13,435 1,031 1,689 1,371 6,855
1978................................................ 1,689 1,614 1,223 1,031 974 1,829 2,365 2,346 1,932 1,949 1,978 1,424 974 2,365 1,696 20,354 1,424 1,876 1,664 8,318
1979................................................ 1,876 1,690 1,678 1,650 2,247 2,165 1,597 1,294 1,037 927 838 1,194 838 2,247 1,516 18,193 1,187 1,668 1,412 7,059
1980................................................ 1,380 1,668 1,630 1,187 1,132 1,235 1,603 1,453 1,291 1,364 1,443 1,305 1,132 1,668 1,391 16,691 980 1,539 1,347 6,734
1981................................................ 1,539 1,534 1,376 980 1,071 1,491 1,733 1,401 1,144 920 899 1,163 899 1,733 1,271 15,251 1,018 1,741 1,426 7,130
1982................................................ 1,594 1,741 1,614 1,018 1,483 1,356 1,551 1,240 1,042 1,135 1,755 1,370 1,018 1,755 1,408 16,899 1,238 1,734 1,458 7,289
1983................................................ 1,238 1,637 1,734 1,310 1,025 1,066 1,080 1,611 1,350 837 986 1,340 837 1,734 1,268 15,214 956 1,652 1,325 6,624
1984................................................ 1,652 1,531 1,145 956 839 831 1,350 1,672 1,523 1,438 1,502 1,330 831 1,672 1,314 15,769 1,042 1,645 1,358 6,789
1985................................................ 1,645 1,601 1,171 1,042 1,139 1,190 1,188 1,117 1,008 830 923 1,338 830 1,645 1,183 14,192 1,140 1,595 1,414 7,072
1986................................................ 1,595 1,454 1,545 1,140 649 890 1,167 1,466 1,148 1,332 1,424 1,227 649 1,595 1,253 15,037 630 1,499 1,166 5,831
1987................................................ 1,452 1,499 1,023 630 942 1,069 1,128 1,118 969 802 766 1,234 630 1,499 1,053 12,632 1,089 1,502 1,266 6,328
1988................................................ 1,313 1,502 1,190 1,089 1,146 1,136 1,177 1,109 816 661 664 1,127 661 1,502 1,078 12,930 940 1,250 1,097 5,484
1989................................................ 1,174 1,250 993 940 1,273 1,333 1,378 1,342 770 675 1,131 1,225 675 1,378 1,124 13,484 927 1,489 1,153 5,767
1990................................................ 1,489 1,075 927 1,051 1,180 1,201 1,211 1,117 654 616 683 1,061 616 1,489 1,022 12,265 767 1,265 1,059 5,297
1991................................................ 1,265 1,170 767 1,034 1,195 1,143 1,187 1,186 818 810 843 1,162 767 1,265 1,048 12,580 775 1,374 1,092 5,461
1992................................................ 1,374 1,173 775 977 1,185 1,156 1,183 1,115 807 612 601 1,121 601 1,374 1,007 12,079 612 1,158 859 4,293
1993................................................ 1,158 764 638 612 937 933 908 971 672 612 652 833 612 1,158 808 9,690 695 877 778 3,889
1994................................................ 877 749 735 695 1,435 1,323 1,168 1,134 932 704 806 1,137 695 1,435 975 11,695 730 1,282 1,028 5,140
1995................................................ 1,282 1,124 867 730 775 659 813 1,832 2,199 2,209 1,852 1,244 659 2,209 1,299 15,586 1,131 1,677 1,335 6,674
1996................................................ 1,409 1,213 1,131 1,677 2,246 2,106 2,252 2,218 2,091 1,615 1,231 1,171 1,131 2,252 1,697 20,360 965 1,407 1,140 5,699
1997................................................ 1,407 1,170 986 965 1,916 2,524 3,523 3,069 2,771 3,040 2,520 1,345 965 3,523 2,103 25,236 1,155 1,368 1,282 6,409
1998................................................ 1,354 1,368 1,187 1,155 1,489 1,529 1,476 1,476 1,260 1,051 1,220 1,287 1,051 1,529 1,321 15,852 1,287 1,615 1,472 7,361
1999................................................ 1,521 1,483 1,455 1,615 1,611 1,769 1,761 1,714 1,393 1,157 1,040 1,203 1,040 1,769 1,477 17,722 1,128 1,385 1,231 6,154
2000................................................ 1,277 1,385 1,128 1,161 1,371 1,445 1,448 1,422 1,068 874 1,246 1,111 874 1,448 1,245 14,936 744 1,155 948 4,741
2001................................................ 1,155 940 791 744 756 823 848 859 680 627 630 793 627 1,155 804 9,646 642 804 748 3,742
2002................................................ 804 735 768 642 787 1,243 1,279 1,300 1,043 852 1,071 1,207 642 1,300 978 11,731 1,066 1,240 1,151 5,755
2003................................................ 1,133 1,240 1,066 1,109 1,151 1,265 1,319 1,296 1,003 663 699 979 663 1,319 1,077 12,923 979 1,330 1,104 5,522
2004................................................ 1,181 1,330 1,024 1,008 969 1,071 1,103 1,059 894 707 758 934 707 1,330 1,003 12,038 721 1,035 877 4,384
2005................................................ 950 721 744 1,035 1,014 893 933 954 840 773 797 945 721 1,035 883 10,599 819 1,097 922 4,611
2006................................................ 1,097 859 891 819 942 1,181 1,265 1,353 1,078 743 782 943 743 1,353 996 11,953 802 980 902 4,512
2007................................................ 980 877 910 802 820 955 980 984 692 666 645 915 645 984 852 10,226 744 924 849 4,247
2008................................................ 924 879 785 744 790 853 837 854 748 ....... ....... ....... ....... ....... ....... ....... ....... ....... ....... .......
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- STATISTICS (JANUARY 1968 TO DECEMBER 2007)
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------NUM................................................. 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40
MIN................................................. 804 721 638 612 649 659 813 859 654 612 601 793 601 984 804 9,646 612 804 748 3,742
MEAN................................................ 1,417 1,358 1,206 1,141 1,306 1,370 1,498 1,478 1,222 1,155 1,178 1,244 877 1,754 1,298 15,573 1,024 1,484 1,260 6,300
MAX................................................. 1,876 1,871 1,881 2,232 2,367 2,524 3,800 3,328 2,771 3,040 2,520 1,815 1,464 3,800 2,103 25,236 1,598 2,232 1,753 8,763
STDEV............................................... 277 321 342 376 476 480 632 522 472 545 460 223 229 577 329 3,943 257 328 277 1,383
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Rows include Jan to Apr of following year.
TABLE 3-2.--AVERAGE DAILY OUTFLOW FOR THE MONTH FROM LAKE SAKAKAWEA, JUNE 1967 TO SEPTEMBER 2008 (IN 1,000 cfs)
[Retrieved on 8-October-2008]
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
MONTH FULL YEAR (Jan-Dec) Colder Months (Dec-Apr)
--------------------------------------------------------------------------------------------------------------------------------------- \1\
YEAR --------------------------
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MIN MAX MEAN MIN MAX MEAN
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1967.......................... ....... ....... ....... ....... ....... 26.5 31.2 35.9 26.2 29.6 26.8 26.6 ....... ....... ....... 19.1 29.8 25.2
1968.......................... 28.3 29.8 19.1 22.2 19.9 16.6 16.4 19.8 23.0 30.9 24.2 25.2 16.4 30.9 23.0 25.2 33.7 28.8
1969.......................... 29.4 33.7 30.6 25.3 23.4 17.5 26.5 29.1 25.6 24.6 25.6 29.5 17.5 33.7 26.7 20.1 29.5 25.8
1970.......................... 26.3 28.0 20.1 25.0 27.7 27.6 26.2 26.8 21.7 26.4 27.8 24.0 20.1 28.0 25.6 24.0 34.7 29.2
1971.......................... 30.3 28.7 28.1 34.7 38.0 34.8 34.7 26.2 23.3 23.5 24.9 23.9 23.3 38.0 29.3 23.9 37.5 29.1
1972.......................... 28.7 28.8 26.7 37.5 38.5 37.2 26.8 23.0 20.4 21.2 22.3 22.8 20.4 38.5 27.8 20.1 26.8 24.0
1973.......................... 26.8 25.1 25.2 20.1 16.9 18.6 19.9 20.6 19.6 18.8 19.7 22.8 16.9 26.8 21.2 19.3 26.7 24.0
1974.......................... 26.1 26.7 25.1 19.3 20.9 23.6 25.8 27.3 23.2 28.4 24.3 24.4 19.3 28.4 24.6 17.5 28.4 23.5
1975.......................... 22.1 28.4 24.9 17.5 31.9 40.1 61.8 54.1 37.2 32.4 33.0 27.9 17.5 61.8 34.3 26.0 31.8 28.7
1976.......................... 26.0 31.5 26.1 31.8 35.7 37.5 36.5 31.2 26.0 25.2 29.0 23.8 23.8 37.5 30.0 16.1 29.3 23.5
1977.......................... 29.3 28.0 20.4 16.1 15.8 15.5 17.4 16.2 14.6 12.6 16.3 21.1 12.6 29.3 18.6 17.3 29.1 23.0
1978.......................... 27.5 29.1 19.9 17.3 15.8 30.7 38.5 38.3 32.5 31.7 33.2 23.2 15.8 38.5 28.1 23.2 30.5 27.8
1979.......................... 30.5 30.4 27.3 27.7 36.5 36.4 26.0 21.0 17.4 15.1 14.1 19.4 14.1 36.5 25.2 19.4 29.0 23.4
1980.......................... 22.4 29.0 26.5 19.9 18.4 20.8 26.1 23.6 21.7 22.2 24.2 21.2 18.4 29.0 23.0 16.5 27.6 22.5
1981.......................... 25.0 27.6 22.4 16.5 17.4 25.1 28.2 22.8 19.2 15.0 15.1 18.9 15.0 28.2 21.1 17.1 31.4 23.9
1982.......................... 25.6 31.4 26.3 17.1 24.1 22.8 25.2 20.2 17.5 18.5 29.5 22.3 17.1 31.4 23.4 20.1 29.5 24.4
1983.......................... 20.1 29.5 28.2 22.0 16.7 17.9 17.6 26.2 22.7 13.6 16.6 21.8 13.6 29.5 21.1 16.0 26.9 22.0
1984.......................... 26.9 26.6 18.6 16.0 13.7 14.0 22.0 27.1 25.6 23.4 25.2 21.6 13.7 27.1 21.7 17.5 28.8 22.7
1985.......................... 26.7 28.8 19.0 17.5 18.5 20.0 19.3 18.2 16.9 13.5 15.5 21.8 13.5 28.8 19.6 19.2 26.2 23.6
1986.......................... 25.9 26.2 25.1 19.2 10.6 14.9 19.0 23.8 19.3 21.7 23.9 20.0 10.6 26.2 20.8 10.6 27.0 19.6
1987.......................... 23.6 27.0 16.6 10.6 15.3 18.0 18.3 18.2 16.3 13.0 12.9 21.0 10.6 27.0 17.6 183 261 212
1988.......................... 21.3 26.1 19.4 18.3 18.6 19.1 19.1 18.0 13.7 10.7 11.2 18.3 10.7 26.1 17.8 15.8 22.5 18.4
1989.......................... 19.1 22.5 16.2 15.8 20.7 22.4 22.4 21.8 12.9 11.0 19.0 19.9 11.0 22.5 18.6 15.1 24.2 19.3
1990.......................... 24.2 19.4 15.1 17.7 19.2 20.2 19.7 18.2 11.0 10.0 11.5 17.3 10.0 24.2 17.0 12.5 21.1 17.8
1991.......................... 20.6 21.1 12.5 17.4 19.4 19.2 19.3 19.3 13.8 13.2 14.2 18.9 12.5 21.1 17.4 12.6 22.3 18.1
1992.......................... 22.3 20.4 12.6 16.4 19.3 19.4 19.2 18.1 13.6 10.0 10.1 18.2 10.0 22.3 16.6 10.3 18.8 14.3
1993.......................... 18.8 13.8 10.4 10.3 15.2 15.7 14.8 15.8 11.3 9.9 11.0 13.6 9.9 18.8 13.4 11.7 14.3 13.0
1994.......................... 14.3 13.5 12.0 11.7 23.3 22.2 19.0 18.4 15.7 11.4 13.6 18.5 11.4 23.3 16.1 12.3 20.9 17.2
1995.......................... 20.9 20.2 14.1 12.3 12.6 11.1 13.2 29.8 37.0 35.9 31.1 20.2 11.1 37.0 21.5 18.4 28.2 22.2
1996.......................... 22.9 21.1 18.4 28.2 36.5 35.4 36.7 36.1 35.1 26.3 20.7 19.0 18.4 36.7 28.0 16.0 22.9 19.0
1997.......................... 22.9 21.1 16.0 16.2 31.1 42.5 57.3 49.9 46.5 49.4 42.3 21.9 16.0 57.3 34.8 19.3 24.6 21.4
1998.......................... 22.0 24.6 19.3 19.4 24.2 25.7 24.0 24.0 21.2 17.1 20.5 20.9 17.1 25.7 21.9 20.9 27.1 24.6
1999.......................... 24.7 26.7 23.7 27.1 26.2 29.7 28.6 27.9 23.4 18.8 17.5 19.6 17.5 29.7 24.5 18.3 24.1 20.5
2000.......................... 20.8 24.1 18.3 19.5 22.3 24.3 23.5 23.1 18.0 14.2 20.9 18.1 14.2 24.3 20.6 12.5 18.8 15.8
2001.......................... 18.8 16.9 12.9 12.5 12.3 13.8 13.8 14.0 11.4 10.2 10.6 12.9 10.2 18.8 13.3 10.8 13.2 12.5
2002.......................... 13.1 13.2 12.5 10.8 12.8 20.9 20.8 21.1 17.5 13.8 18.0 19.6 10.8 21.1 16.2 17.3 22.3 19.2
2003.......................... 18.4 22.3 17.3 18.6 18.7 21.3 21.4 21.1 16.9 10.8 11.7 15.9 10.8 22.3 17.9 15.9 23.1 18.4
2004.......................... 19.2 23.1 16.7 16.9 15.8 18.0 17.9 17.2 15.0 11.5 12.7 15.2 11.5 23.1 16.6 12.1 17.4 14.6
2005.......................... 15.4 13.0 12.1 17.4 16.5 15.0 15.2 15.5 14.1 12.6 13.4 15.4 12.1 17.4 14.6 13.8 17.8 15.4
2006.......................... 17.8 15.5 14.5 13.8 15.3 19.8 20.6 22.0 18.1 12.1 13.1 15.3 12.1 22.0 16.5 13.5 15.9 15.1
2007.......................... 15.9 15.8 14.8 13.5 13.3 16.0 15.9 16.0 11.6 10.8 10.8 14.9 10.8 16.0 14.1 12.5 15.3 14.1
2008.......................... 15.0 15.3 12.8 12.5 12.9 14.3 13.6 13.9 12.6 ....... ....... ....... ....... ....... ....... ....... ....... .......
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ STATISTICS (JANUARY 1968 TO DECEMBER 2007)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------NUM........................... 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40
MIN........................... 13.1 13.0 10.4 10.3 10.6 11.1 13.2 14.0 11.0 9.9 10.1 12.9 9.9 16.0 13.3 10.3 13.2 12.5
MEAN.......................... 23.0 24.2 19.6 19.2 21.2 23.0 24.4 24.0 20.5 18.8 19.8 20.3 14.5 29.1 21.5 17.0 25.1 21.0
MAX........................... 30.5 33.7 30.6 37.5 38.5 42.5 61.8 54.1 46.5 49.4 42.3 29.5 23.8 61.8 34.8 26.0 37.5 29.2
STDEV......................... 4.5 5.7 5.6 6.3 7.7 8.1 10.3 8.5 7.9 8.9 7.7 3.6 3.8 9.3 5.4 4.1 5.7 4.6
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Rows include Jan to Apr of following year.
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 3-7.--Annual total outflow from Lake Sakakawea at Garrison Dam
from 1968 to 2007 (Source of data: USACE).
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 3-8.--Daily Discharge in the Missouri River at Bismarck from
1958 to 2008 (Source of data: USGS).
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 3-9.--Annual mean discharge at Bismarck from 1958 to 2007
(Source of data: USGS).
TABLE 3-3.--MONTHLY MEAN FLOW AT BISMARCK
[USGS Gaging Station 06342500]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Month
Year ------------------------------------------------------------------------------------------------------------ Mean
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
--------------------------------------------------------------------------------------------------------------------------------------------------------
1958............................... 14,190 13,270 15,370 19,090 20,770 29,370 14,730 17,680 29,710 20,430 16,750 14,970 18,861
1959............................... 14,580 15,990 16,150 16,800 21,000 21,340 20,950 21,680 21,220 16,200 15,590 14,970 18,039
1960............................... 15,110 18,360 19,600 14,190 13,260 8,445 10,840 12,760 12,560 10,000 12,330 15,120 13,548
1961............................... 20,620 20,090 20,880 20,790 19,340 14,350 13,760 16,590 9,369 16,410 25,180 16,080 17,788
1962............................... 21,710 23,540 24,080 23,540 22,310 22,140 13,800 9,271 8,121 8,399 8,155 14,330 16,616
1963............................... 20,270 20,200 22,440 17,000 9,234 16,720 17,140 9,821 9,683 11,600 17,010 24,590 16,309
1964............................... 24,320 28,000 25,850 20,550 17,780 21,390 14,590 13,600 18,920 17,150 23,770 21,780 20,642
1965............................... 28,230 31,430 31,390 29,090 23,870 27,630 22,610 14,490 13,140 29,460 33,950 31,260 26,379
1966............................... 20,680 27,810 25,760 10,510 10,900 13,350 18,700 20,230 17,440 21,090 25,600 23,060 19,594
1967............................... 27,020 32,610 31,710 19,220 10,900 27,130 32,920 39,400 28,760 32,390 28,900 27,350 28,193
1968............................... 27,690 33,310 23,700 23,570 21,500 18,570 17,950 22,380 24,910 35,080 26,360 28,270 25,274
1969............................... 32,350 34,840 33,550 32,350 26,060 19,930 29,740 33,300 28,880 26,860 28,520 31,690 29,839
1970............................... 26,980 29,840 22,530 28,020 31,950 31,050 28,720 29,920 24,170 28,730 31,060 27,310 28,357
1971............................... 28,300 29,850 32,760 38,220 40,950 37,360 36,910 28,910 26,260 26,450 27,240 24,150 31,447
1972............................... 31,220 30,500 34,370 40,370 42,030 40,800 30,130 26,230 22,650 22,970 24,910 21,220 30,617
1973............................... 28,190 27,220 27,860 22,660 18,000 19,690 21,450 21,910 20,930 20,340 21,110 23,970 22,778
1974............................... 27,500 28,740 28,360 21,850 23,030 25,680 28,060 29,780 25,920 29,480 26,400 25,920 26,727
1975............................... 24,470 30,180 27,350 22,650 35,450 43,540 64,610 57,010 39,700 34,210 34,390 29,100 36,888
1976............................... 28,060 34,640 29,570 34,700 38,030 40,880 39,680 34,990 29,410 28,370 32,460 26,500 33,108
1977............................... 29,100 30,700 23,580 17,950 17,200 17,250 18,850 17,790 16,230 14,050 17,190 22,980 20,239
1978............................... 27,770 30,710 26,070 23,060 17,550 33,030 42,410 42,260 35,460 34,550 35,040 24,710 31,052
1979............................... 31,730 32,550 29,180 33,950 40,120 40,370 28,940 22,870 18,850 16,650 15,250 20,570 27,586
1980............................... 23,310 29,790 28,630 22,090 19,630 22,380 27,520 25,350 23,610 23,750 25,620 22,270 24,496
1981............................... 26,150 29,700 25,170 17,630 19,330 27,490 30,350 25,120 20,430 16,940 16,130 20,320 22,897
1982............................... 27,850 34,790 31,130 24,830 26,560 26,310 27,580 22,490 19,810 20,750 31,480 26,120 26,642
1983............................... 21,210 31,640 32,790 24,010 18,790 19,660 19,790 27,470 25,090 16,230 18,490 22,480 23,138
1984............................... 28,430 28,810 22,950 18,290 16,030 16,650 23,350 29,010 27,760 25,860 27,690 23,380 24,018
1985............................... 27,980 31,490 22,230 20,660 21,320 23,160 22,030 20,810 19,340 14,340 15,850 22,870 21,840
1986............................... 27,710 28,610 31,730 22,470 12,840 15,640 20,940 26,290 21,610 23,250 26,340 22,020 23,288
1987............................... 25,720 29,530 20,590 12,580 16,510 19,940 20,820 20,930 18,290 14,910 14,490 23,040 19,779
1988............................... 23,930 31,280 24,380 21,140 20,520 21,040 21,210 19,780 15,050 11,110 11,170 20,400 20,084
1989............................... 20,190 24,540 17,370 17,020 22,550 24,870 24,820 24,400 14,640 11,630 20,150 21,210 20,283
1990............................... 26,020 21,930 17,820 19,010 20,520 22,150 21,720 19,720 12,680 11,000 12,070 18,590 18,603
1991............................... 21,900 22,290 14,570 18,370 21,480 21,560 21,610 21,840 15,500 14,170 14,810 19,450 18,963
1992............................... 23,050 21,160 14,240 17,180 20,910 20,620 20,730 19,410 14,700 10,970 10,930 18,650 17,713
1993............................... 19,330 14,270 10,670 10,420 15,930 17,020 19,270 17,650 12,900 11,040 11,520 13,590 14,468
1994............................... 14,160 13,640 13,490 12,520 25,520 25,400 20,870 19,920 17,160 13,690 14,590 20,810 17,648
1995............................... 23,080 24,250 17,780 13,130 13,840 11,660 13,580 32,180 42,670 40,150 34,980 21,710 24,084
1996............................... 24,440 23,620 20,730 31,350 38,960 38,470 39,500 39,320 38,060 28,510 22,470 20,260 30,474
1997............................... 24,340 22,660 21,700 18,380 32,310 42,580 56,770 48,100 45,060 48,180 43,240 23,550 35,573
1998............................... 23,490 26,230 20,750 19,270 23,530 25,890 24,490 24,640 21,430 15,640 19,870 21,610 22,237
1999............................... 24,570 26,690 26,610 27,080 26,480 29,930 28,830 28,500 24,660 20,240 17,970 20,420 25,165
2000............................... 22,090 25,910 19,950 19,940 22,190 25,470 24,940 24,660 19,400 14,690 20,880 18,740 21,572
2001............................... 19,480 17,740 16,060 14,090 12,430 14,550 14,190 14,130 11,290 10,160 10,510 13,250 13,990
2002............................... 13,360 13,530 13,030 11,800 12,630 22,030 21,780 22,260 18,820 14,240 18,370 21,020 16,906
2003............................... 19,280 23,560 18,710 19,210 19,490 22,810 22,660 21,850 17,160 10,770 11,460 15,960 18,577
2004............................... 19,950 24,610 19,180 17,590 15,450 18,440 18,090 17,230 15,060 11,590 12,580 15,600 17,114
2005............................... 16,000 13,540 12,870 17,850 17,430 16,160 16,220 16,140 14,810 13,070 13,680 16,060 15,319
2006............................... 18,690 16,100 15,130 13,920 15,130 20,280 21,350 22,970 20,080 12,830 13,470 15,780 17,144
2007............................... 16,470 16,430 15,990 14,090 13,270 16,770 16,300 16,670 12,840 11,410 ....... ....... 15,024
====================================================================================================================
Mean 1958-2007..................... 23,445 25,454 22,767 20,921 21,656 23,979 24,576 24,234 21,244 19,840 21,183 21,409 22,538
Mean 1968-2007..................... 24,139 26,036 22,628 21,382 22,836 24,927 26,219 25,905 22,332 20,222 21,301 21,681 23,274
--------------------------------------------------------------------------------------------------------------------------------------------------------
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 3-10.--Monthly mean discharge rates at Bismarck during the five
colder months (December to April) from 1968 to 2007 (Source of data:
USGS).
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 3-11.--Monthly outflow at Garrison Dam vs. monthly discharge at
Bismarck (1968 to 2007) (Sources of data: USACE, USGS).
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 3-12.--Monthly outflow at Garrison Dam and monthly discharge at
Bismarck (1967 to 2008). Higher discharges at Bismarck reflect the
added runoff from the watershed downstream of Garrison Dam (Sources of
data: USACE, USGS).
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 3-13.--Residual discharge after subtracting outflow at Garrison
Dam from the discharge at Bismarck, reflecting the runoff from the
watershed between Garrison Dam and Bismarck (1967 to 2007) (Sources of
data: USACE, USGS).
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 3-14.--Percent flow at Bismarck relative to the outflow at
Garrison Dam for different periods of the year (1967 to 2007). Highest
additional discharge occurred during the spring melting season.
(Sources of data: USACE, USGS).
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 3-15.--Monthly releases at Garrison Dam, relative to total
annual releases, showing that highest releases occur during the peak
demand periods in December, July, and August (Sources of data: USACE).
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 3-16.--Stage-discharge relationship in Bismarck, reflecting an
increase of the stage at high flows (USACE, 2004c).
3.3.3. Hydropower Generation
Water release rates at Garrison Dam for ice-in vary from year to
year depending on the specific conditions and needs of other uses.
Under ``normal conditions'', the USACE would release from ``the top of
the maintenance zone'' and gradually release the water over the winter.
However, reduced runoff in the watershed has resulted in a decline in
power generation between 1967 and 2008 by almost a factor of 2 (Figure
2-10). Using linear regression, the decline was approximately 8 percent
greater during the 5-month-long colder period (December to April) than
during the other months of the year (Figure 3-18). Specifically, the
greatest decline in the colder period occurred during January-February
and ice-out (March-April) (Figure 3-19).
TABLE 3-4.--CHANNEL CHANGES DOWNSTREAM OF GARRISON DAM BETWEEN 1958 AND 1985 (USACE, 1993c).
[QUALITATIVE ACTIVE CHANNEL CHANGES 1958 TO 1985 FOR A DISCHARGE OF 20,000 CFS]
----------------------------------------------------------------------------------------------------------------
THALWEG AVE. BED D50 GRAIN
1960 R.M. ELEV ELEV AVE DEPTH WIDTH AREA SIZE
----------------------------------------------------------------------------------------------------------------
1388.19....................................... - - - + - +
1387.09....................................... - - + - - +
1385.88....................................... - - - + - +
1384.86....................................... - - - - - +
1383.33....................................... - - + - - +
1382.25....................................... - - * - - -
1381.34....................................... - - - - - +
1380.43....................................... - - + - - +
1379.68....................................... - - - + - +
1379.00....................................... - - - + - +
1378.42....................................... - - * * - +
377.53........................................ * - - + - +
1376.71....................................... - - - - + +
375.89........................................ - - - - - +
374.91........................................ - - - - - +
1374.58....................................... - - * - - +
1373.80....................................... + - + + + +
1372.50....................................... - - + * + +
1371.37....................................... - - - - - +
1370.29....................................... + - * * - +
1368.89....................................... * - - + + +
1367.40....................................... - - - - - +
1366.24....................................... - - + - - +
1364.87....................................... + - + - - +
1363.86....................................... + - - - - +
1362.55....................................... + - - + - -
1360.40....................................... - - + - - -
1358.50....................................... * - - + + +
1356.50....................................... * - + + + +
1353.85....................................... + - - - - +
1351.83....................................... + - - * * +
1349.46....................................... - - - + + +
1346.46....................................... - - + + + -
1344.72....................................... - - + - - -
1343.30....................................... - - - + - -
1341.40....................................... + - - + + +
1339.67....................................... - - * + + -
1338.05....................................... - - + + + +
1336.82....................................... - - - + + -
1335.91....................................... - - * - + +
----------------------------------------------------------------------------------------------------------------
* NO CHANGE OR INCOMPLETE DATA.
- MEASURED UNITS HAVE DECREASED FOR THAT PARAMETER OR MSL ELEVATION HAS DECREASED.
+ MEASURED UNITS HAVE INCREASED FOR THAT PARAMETER OR MSL ELEVATION HAS INCREASED.
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 3-17.--Tailwater elevation changes at Garrison Dam at different
flows, reflecting the degradation of the channel since the construction
of the dam (USACE, 2004c).
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 3-18.--Monthly gross energy generation in colder and warmer
periods, showing a slightly greater decrease during colder months over
time compared to warmer months (Source of data: USACE).
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 3-19.--Monthly gross energy generation in colder and warmer
periods, with higher resolution during colder months (Source of data:
USACE).
Power generation during the colder period accounted for 58 percent
of the total annual power generation; this value has decreased to 53
percent (Figure 3-20). Although there are other potential causes for a
relatively greater decline during the winter months (such as the
statistical effect of the floods in the mid-1990s), the decline could
have been caused by aggradation in the Missouri River in the headwater
of Lake Oahe.
Siltation in the river has resulted in aggradation and widening of
the river channel south of Bismarck. In urban areas such as Bismarck
and Mandan the river channel cannot widen without an increased risk of
flooding and the loss of property. As a result, the flow release rates
have been reduced over time to prevent flooding. This effect is
expected to continue. The risk is higher during wet years when the
elevation of Lake Oahe is higher, and consequently its headwaters
extend further north, and thus more sediments is being deposited again
closer to the urban areas of Bismarck and Mandan than at the present
time. It is likely that power generation in winter during wet years
will decrease as a result. However, high inflows to the reservoir
during wet years may require higher water release rates even during the
colder months. This condition occurred during the wet years between
1995 and 2000 when release rates (and thus energy generation) during
colder months were approximately 50 percent higher than during
subsequent years (i.e., from year 2001 to the present) (Figure 3-18).
One of the biggest impacts to hydropower generation from ice dams
is the reduction in flexibility of hydropower generation in winter (if
the risk for flooding is to be reduced). Specifically, as stated above,
the power plant cannot be operated as an optimally efficient peaking
facility.
Prevention of flooding means that the water from Lake Sakakawea is
released at a different time of the year, generating power at that
time. Since rates applied to power generated at the Garrison Dam do not
vary on a month-by-month basis, annual revenues from power generation
are thus not lost. The total annual revenue from energy generation
would only be adversely affected if water is released from Lake
Sakakawea during warmer months in excess of the maximum generating
capacity of Garrison Dam (41,000 cfs), in order to prepare for reduced
releases during the colder months.
However, winter is one of the peak power demand periods. Thus,
reduced power generation capacity in winter at the Garrison Dam power
plant may mean that power from other, potentially more expensive
sources needs to be generated to accommodate demand.
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 3-20.--Power generation during colder months (5-month period)
relative to total annual generation (Source of data: USACE).
4.0 RECOMMENDATIONS
Releases from Garrison Dam by the USACE for various uses already
aim to minimize flooding. Detailed monitoring data should continue to
be collected to allow for effective adaptive management measures of the
operations of Garrison Dam to maximize the benefit of the dam and the
overall System, while minimizing impacts. This is particularly
important in light of the fact that there are a number of natural
variables that change regularly (daily, as well as longterm), such as
rainfall, temperature, flow, erosion and deposition patterns, etc. In
addition, the river serves multiple uses that also need to be balanced,
e.g., navigation, flood protection, irrigation, recreation, etc.
Specifically in winter, flood protection from ice dams is a more
important driver for the determination of the release rates.
Dredging could be considered on a temporary and localized basis for
flood control, but a larger-scale dredging operation would most likely
be cost-prohibitive. Dredging has been conducted for selected water
intakes which are affected by sedimentation (such as the power plant
Leland Olds in Stanton). Small-scale dredging for similar purposes is
probably cost-effective.
The risk of flooding will increase once the current drought has
passed, and Lake Oahe again has full pool elevations. Higher pool
elevations imply that sediment carried by the Missouri River will be
settling out closer to the city of Bismarck than at present which will
result in further aggradation. A higher risk of flooding requires
further reduction in hydropower generation at Garrison Dam. The
existing flood plain and zoning should be reviewed in the cities of
Bismarck and Mandan to determine if additional steps should be
undertaken to better accommodate high flows in the Missouri River.
Supposedly, there has been additional development down close to the
river edge around the city. Such developments should be avoided, or
potentially even reversed if feasible. Similarly, the flood plain and
zoning in other potentially affected areas (i.e., non-urban areas)
should be reviewed. Further, appropriate bank stabilization measures
should be considered in areas most heavily affected by flooding. After
all, when reservoir levels are high during wetter years, more water
needs to be passed through the river, which will limit the reduction in
flow that can be achieved in the winter (as occurred during the wet
period from 1995 to 2000; Figure 3-18).
As suggested by the Water Commission in their comments to the draft
report, it is recommended to conduct a study that more quantitatively
demonstrates that higher elevations in Lake Oahe will result in a
decrease in flow velocities due to aggradation. This study would need
to address the range of variables that affect the flow in order to
extract the impact of lake elevations on outflow rates. A first-order
assessment was conducted during this study, comparing average outflow
rates at Garrison Dam with elevation in Lake Oahe, although the
available data were insufficient to quantitatively address the range of
variables. The recommended assessment should include an estimate of
future trends of sedimentation and resulting impacts.
5.0 REFERENCES
Berger (Louis Berger Group, Inc.), 2008, Identification and sources
and deposits and locations of erosion and sedimentation. Prepared for
the U.S. Army Corps of Engineers Omaha District and the Missouri River
Joint Water Board (August 2008).
Biedenharn, S.S., R.S. Soileau, L.C. Hubbard, P.H. Hoffman, C.R.
Thorne, and C.C. Bromley, 2001, Missouri River-Fort Peck Dam to Ponca
State Park Geomorphological Assessment related to Bank Stabilization.
FEMA, (Federal Emergency Management Agency), 2005, Flood Insurance
Study, Burleigh County, North Dakota, and incorporated areas.
Geiger, A.F., 1963, Developing sediment storage requirements for
upstream retarding reservoirs. Proc. Federal Interagency Sedimentation
Conf., USDA-ARS Misc. Pub. 970, p. 881-885. Cited in: Morris, G.L. and
J. Fan, 1997, Reservoir Sedimentation Handbook.
NDGFD (North Dakota Game and Fish Department), 2002, The Missouri
and Yellowstone Rivers in North Dakota, Williston Reach)--A Report to
the Director. http://gf.nd.gov/multimedia/news/positions/mo-riv-
whitepaper-williston.html.
Remus, J., P.E., 2008, Sedimentation in the Upper Missouri River
Basin. U.S. Army Corps of Engineers. http://watercenter.unl.edu/
MoRiverMainstem/Sedimentation.asp. Accessed November 13, 2008.
USACE (U.S. Army Corps of Engineers), 1978, Buford Trenton
Irrigation District: Backwater and drainage problems. USACE Omaha
District, Omaha Nebraska, Design Memorandum MGR146.
USACE (__), 1992, Williston area studies. Aggradation analysis.
USACE Omaha District, Nebraska, Draft report.
USACE (__), 1993a, Aggradation, Degradation, and Water Quality
Conditions: Missouri River Mainstem Reservoir System. USACE Omaha
District.
USACE (__), 1993b, Lake Oahe aggradation study. USACE Omaha
District, M.R.D. Sediment Memoranda, No. 15.
USACE (__), 1993c. Downstream Channel and Sediment Trends Study.
USACE Omaha District.
USACE (__), 1999, Missouri River Main Stem Reservoirs Hydrologic
Statistics. RCC Technical Report F-99. USACE Missouri River Region
Resevoir Control Center.
USACE (__), 2000a, Downstream Channel and Sediment Trend Study
Update. Garrison Project--North Dakota. Prepared by Sedimentation and
Channel Stabilization Section, Hydrologic Engineering Branch (M.R.D.
Sediment Memoranda, No. 1 6A).
USACE (__), 2004a, Missouri River Final Environmental Impact
Statement, Master Water Control Manual Review and Update.
USACE (__), 2004b, Record of Decision, Master Water Control Manual
Review and Update.
USACE (__), 2004c, Missouri River stage trends. RCC Technical
Report A-04. Prepared by Reservoir Control Center, USACE Northwestern
Division--Missouri River basin, Omaha, Nebraska.
USACE (__), 2006, Missouri River Mainstem Reservoir System, Master
Water Control Manual, Missouri River Basin. Reservoir Control Center,
USACE Northwestern Division--Missouri River Basin.
USGS (United States Geological Survey), 1995, Transport and sources
of sediment in the Missouri River between Garrison Dam and the
headwaters of Lake Oahe, North Dakota, May 1988 through April 1991.
USGS Water-Resources Investigations Report 95-4087. Prepared in
cooperation with the USACE.
USGS (__), 2008, Flow data at the Bismarck gaging station. Accessed
on Nov. 8, 2008. http://waterdata.usgs.gov/nwis/nwisman/
?site_no=06342500&agency_cd=USGS.
Williams, G.P. and M.G. Wolman, 1984, Downstream effects of dams on
alluvial rivers. U.S. Geological Survey Professional Paper 1286, 83p.
Wuebben, J.L. and J.J. Gagnon, 1995, Ice jam flooding on the
Missouri River near Williston, North Dakota. Accessed at: http://
www.tpub.com/content/ArmyCRREL/CR95_19/CR95_190007.htm.
PERSONAL COMMUNICATION
Larry Cieslik, Chief, Reservoir Control Center, U.S. Army Corps of
Engineers; November 6, 2008.
Bruce Engelhardt, Investigations Section Chief, North Dakota State
Water Commission; November 11, 2008.
Jody Farhat, P.E., Power Production Team Leader, Missouri River
Basin Water, Management Division, Northwestern Division, U.S. Army
Corps of Engineers, Omaha, NE; November 10, 2008.
James Mueller, Chief, Maintenance Engineering Section, U.S. Army
Corps of Engineers; January 8, 2009.
Bill Mulligan, Chief, Civil Works Project Management, U.S. Army
Corps of Engineers, Omaha, NE; November 17, 2008.
John Remus, Chief, Hydrologic Engineering Branch, U.S. Army Corps
of Engineers, Omaha, NE; November 7, 2008.
Ronald Sando, Water Resources Consultant, Missouri River Joint
Water Board; October 24, 2008.
John Stonebarger, UGP Energy Marketing Supervisor, Western Area
Power Administration, November 10, 2008.
U.S. Geological Survey, North Dakota Water Science Center,
Bismarck, ND; November 12, 2008.
Peter Whiting, Associate Dean of the College of Arts and Sciences,
and Associate Professor of Geological Sciences, Case Western Reserve
University, Cleveland, OH; October 23, 2008.
Acknowledgment
We greatly appreciate the time and effort of the persons listed
above to provide helpful documentation and information for this
project.
----------------------------------------------------------------
EXHIBIT 1--Combined Reservoir Regulation and Power Production Order No.
St-2, 1983
Garrison Standing Order
To: Garrison Office Attn: Project Engineer
From: Reservoir Control Center
Re: Garrison Combined Reservoir Regulation and Power Production Order
No. St-2, 1983. This order will apply when referenced in the
Daily Reservoir Regulation and Power Production Orders.
1. Minimum energy generation shall be maintained to avoid low
pumping stages below Garrison as follows:
Period Minimum Energy for Period
4 hours 300 MWh
5 hours 400 MWh
6 hours 550 MWh
7 hours 700 MWh 8 hours 850 MWh
The WAPA power systems dispatcher shall be advised whenever it
appears that loading is falling below the above minimums so that plant
loading can be increased. The above minimums have been furnished to
WAPA.
2. Unless otherwise specified in daily reservoir regulation and
power production orders supplementary releases will be made only as
necessary to maintain daily average discharge of 6,000 cfs. The WAPA
dispatcher will be notified as far in advance as possible of the intent
to make supplementary releases.
----------------------------------------------------------------
appendix e--impact of silation of the missouri river on fish and
wildlife in north dakota
1.0 INTRODUCTION
The contemporary Missouri River in North Dakota is highly modified
from its natural character due to the Flood Control Act of 1944. The
Flood Control Act was Federal legislation that led to the establishment
of the Pick-Sloan Plan to construct six large dams on the Missouri
River mainstem from Nebraska to Montana.
The completion of the Pick-Sloan Plan has had several implications
for the ecology of the river. The creation of reservoirs has converted
riverine to lacustrine habitat (NRC, 2002; Galat et al., 2005) by
stabilizing river flows (Hesse and Mestl, 1993; Galat and Lipkin,
2000). The stabilization of flows and the presence of dams cause
sediment to become trapped in the reservoirs, resulting in a sediment
deficit downstream (Macek-Rowland, 2000; Galat et al., 2005).
Reservoirs also reduce channel meandering, resulting in a decline in
off-channel habitat (Shields et al., 2000).
North Dakota contains one dam, Garrison Dam, and its associated
reservoir, Lake Sakakawea. The reservoir known as Lake Oahe, formed by
the Oahe Dam in South Dakota, also extends into North Dakota from the
south. Therefore, from an ecological perspective, the Missouri River in
North Dakota may be thought of as having four parts:
--The Williston Reach.--The riverine segment close to the Montana
border, into which the Yellowstone River flows and which flows
into Lake Sakakawea;
--Lake Sakakawea.--The reservoir formed by Garrison Dam (closed in
1953), whose entire range is within the state of North Dakota;
--The Garrison Reach.--The riverine segment from Garrison Dam to the
headwaters of Lake Oahe; and
--Lake Oahe.--The reservoir formed by Oahe Dam in South Dakota
(closed in 1958) and which is in both North Dakota and South
Dakota.
2.0 DESCRIPTION OF THE RESOURCE
The creation of these reservoirs has resulted in a suite of
ecological changes, including the creation of major warm water sport
fisheries. It has also resulted in declines for many of the native fish
that were adapted to the pre-impoundment conditions. Therefore, in this
section, we will define the ``resource'' as two groups of animals:
those that constitute a conservation concern and those that are
important for recreational purposes (hunting and fishing). These are
hereafter referred to as ``Conservation Species'' and ``Recreational
Species,'' respectively.
2.1 Conservation Species
Within the first group, we include those animals that are listed as
species of conservation priority in the North Dakota Wildlife Action
Plan (NDWAP) of 2005. The NDWAP report uses a ``conservation priority''
system that rates a species at a particular ``level'' of conservation
priority.\1\ The report then divides the State of ND into geographic
focus areas. Our intent is to include in the ``conservation species''
group all those species of conservation priority that are listed in the
NDWAP's ``Missouri River and Breaks'' section, which lists all of the
animals of conservation priority that fall within the Missouri River
focus area in the State of ND. The section can be found on page 71 of
the NDWAP report.
---------------------------------------------------------------------------
\1\ ``Level I species are those having a high level of conservation
priority because of declining status in North Dakota or across their
range; or have a high rate of occurrence in North Dakota, constituting
the core of the species breeding range, but may be at-risk range-wide.
Level II species are those having a moderate level of conservation
priority; or a high level of conservation priority but a substantial
level of non-[State wildlife grant] funding is available to them. Level
III species are those having a moderate level of conservation priority
but are believed to be peripheral or non-breeding in North Dakota''
(Hagen et al., 2005, p.10).
---------------------------------------------------------------------------
We do not include the species of conservation priority that are not
listed in the ``Missouri River and Breaks'' geographic focus area as
per the NDWAP report of 2005. Such animals have ranges that fall
outside of the Missouri River mainstem system.
The species listed under the ``Missouri River and Breaks''
geographic focus area of the NDWAP are:
--Birds.--Bald eagle (Haliaeetus leucocephalus), piping plover
(Charadrius melodius), least tern (Sterna antillarum), red-
headed woodpecker (Melanerpes erythrocephalus), golden eagle
(Aquila chyrsaetos)
--Mammals.--River otter (Lotra Canadensis)
--Reptiles and Amphibians.--Smooth softshell turtle (Apalone mutica),
false map turtle (Graptemys pseudogeographica)
--Fish.--Sturgeon chub (Macrhybopsis gelida), pearl dace (Margariscus
margarita), blue sucker (Cycleptus elongatus), paddlefish
(Polydon sp athula), pallid sturgeon (Scaphirhynchus albus),
flathead catfish (Pylodictis olivaris), flathead chub
(Platygobio gracilis), sicklefin chub (Macrhybopsis meeki),
yellow bullhead (Ameiurus natalis)
The pallid sturgeon, in addition to being listed as a species of
conservation priority, is also a federally endangered species. The
piping plover and the least tern are also federally threatened species.
While the NDWAP report lists the pearl dace (Margariscus margarita)
and the yellow bullhead (Ameiurus natalis) in the ``Missouri River and
Breaks'' section, we do not include the yellow bullhead and the pearl
dace in our analysis. These fish either do not use the Missouri River
mainstem, or only very rarely make use of it, and so they fall outside
the scope of this report.
2.2 Recreational Species
The recreational species group includes the most popular game fish
as described in the creel surveys prepared for the year 2006 by NDGF
(Brooks et al., 2007a, 2007b). According to these surveys, the most
popular sport fish in Lake Sakakawea, by estimated number of fish
caught during 2006, in order of popularity, are: walleye, sauger,
northern pike, Chinook salmon, white bass, and channel catfish. The
order from most popular to least popular in Lake Oahe is walleye,
channel catfish, sauger, northern pike, white bass, and Chinook salmon.
Full details, including the estimates and the methods used to
accomplish these estimates, are available in Brooks et al (2007a,
2007b).
The recreational species group also includes a bird species that is
important for recreational hunting on the Missouri River: the Canada
goose (Branta Canadensis).\2\ The Canada goose is a game species, and
over 100,000 of them are shot in the State of North Dakota every year
(Richkus et al., 2008), a significant proportion of which are shot on
the Missouri River mainstem and floodplain. We also include beavers and
muskrats, as hunting and trapping occurs for these animals on the
Missouri River (Fred Ryckman, 2008, personal communication). White-
tailed deer is another game species that is hunted on the Missouri
River floodplain. However, the species is not evaluated here because
neither the literature nor the interviews indicated that siltation has
any effect on white-tailed deer.
---------------------------------------------------------------------------
\2\ Steve Dyke, a conservation biologist for NDGF suggested we
consider the Canada goose as part of this assessment.
---------------------------------------------------------------------------
3.0 AREAS WHERE THE RESOURCE COULD BE IMPACTED BY SEDIMENTATION
In this section we summarize sediment dynamics in the Missouri
River in North Dakota for each of the four river sections defined in
Section 1. We also summarize the key areas in which increased
sedimentation will affect the resource.
3.1 Williston Reach
Suspended sediment in the Williston Reach comes from the mainstem
upstream, beginning at the Fort Peck Dam in Montana, and from the
Yellowstone River, which flows into the Missouri River near the western
edge of the North Dakota/Montana border. The sediment load from the
Yellowstone River supports near pre-impoundment levels of turbidity in
the Williston reach; therefore, the reach exhibits many of the
characteristics of the pre-impoundment Missouri River (Ryckman, 2000;
Lambing and Cleasby, 2006; Steven Krentz, 2008, personal
communication). When this sediment load meets the slow-moving
headwaters of Lake Sakakawea, it settles out and forms a delta. This
reach connects fish that reproduce successfully in the Yellowstone
River (such as paddlefish, pallid sturgeon, and blue suckers) with the
Missouri River.
3.2 Lake Sakakawea
Lake Sakakawea is a reservoir of approximately 286 kilometers in
length (Galat et al., 1996). It has a delta that is 61 kilometers in
length, formed by the deposition of sediment from the Williston reach
(Galat et al., 2005). Lake Sakakawea's waters are colder, clearer,
deeper, and have a more stable hydrograph (seasonal floods have been
eliminated; Hesse and Mestl, 1993; Galat and Lipkin, 2000) than the
Missouri River mainstem before dam construction. The ecology of the
Lake Sakakawea delta has not been studied intensively (Fred Ryckman,
2008, personal communication). However, it has been observed that the
waters beyond the delta are clear, and that this area supports a large
fishery with abundant walleye, northern pike, and sauger populations.
Paddlefish are often found in Lake Sakakawea, although they do not
reproduce successfully there (Fred Ryckman, 2008, personal
communication; Scarnecchia et al., 2008).
3.3 Garrison Reach
Whereas the Williston reach contains near pre-regulation levels of
sediment due to import from the sediment-rich Yellowstone River and
from the mainstem upstream, the Garrison reach between Garrison Dam and
the headwaters of Lake Oahe is relatively deprived of sediment due to
the retention of sediment in Lake Sakakawea. Major sources of sediment
in this reach come from tributaries (Macek-Rowland, 2000) and from
river-bed erosion on the mainstem. Among these tributaries, the Heart
River is the most important contributor of sediment (Macek-Rowland,
2000). The Garrison reach is not well-studied, and little is known
about the ecology of this segment of the river (Steven Krentz, 2008,
personal communication).
3.4 Lake Oahe
Lake Oahe, formed by the Oahe Dam in South Dakota, is the longest
of the six Pick-Sloan Reservoirs, 372 kilometers in length (Galat et
al., 1996). A sediment load from the Garrison reach forms a delta that
is 103 kilometers in length (Galat et al., 2005). Only a third of Lake
Oahe is located within North Dakota, with the remainder in South
Dakota. Lake Oahe supports a fishery with abundant walleye, northern
pike, and sauger populations. Paddlefish are found in Lake Oahe,
although it is unclear where they reproduce, as they are not known to
reproduce in the reservoir itself (Fred Ryckman, 2008, personal
communication).
3.5 Key Areas Where the Resource Could be Impacted by Sedimentation
An increased sediment load in the reservoirs would mean increased
sediment aggradation due to the decreased maximum water velocity
associated with reservoirs and the considerably limited ability of
reservoirs to transport sediment downstream. Aggradation would cause
deltas to increase in size (Palmieri et al., 2001, cited in Kaemingk et
al., 2007) and could lead to sediment accumulation behind dams. An
increased sediment load would also increase turbidity in the inter-
reservoir reaches. In the reservoirs, turbidity would increase in the
headwaters while the remainder of the reservoir would remain clear, due
to the low water velocity in reservoirs that would cause suspended
sediment to settle out (Blevins, 2006). The impacts on different
species of fish and wildlife would not be uniform, as some species
benefit in some reaches while others are negatively affected. These
differences are the result of a particular species' life-cycle
characteristics as they relate to each particular portion of the river.
As we discuss below, many of the key recreation species of fish
require clear and sediment-free water for their prosperity. Therefore,
sedimentation and increased turbidity have negative impacts on their
populations. However, current conditions do allow for abundant
recreational fisheries.
An increased sediment load could presumably have benefits for some
of the conservation species that are adapted to life in a turbid
environment. However, other physical factors being equal, increased
sediment loading alone is not likely to be sufficient to restore or
support the populations of these species.
Other conservation species would benefit from an increase in the
amount of sandbar habitat available. Increased sedimentation could
potentially generate new sandbar habitat; the deficit of sandbar
habitat is in many areas a result of reduced sediment load due to
sediment retention by dams (NRC, 2002). Colonization of sandbars by
cottonwood and willow trees constitutes another important part of
habitat generation for many species. However, such colonization would
require seasonal floods of a magnitude commensurate with those of the
Missouri River during pre-regulation times, which are now absent
(Johnson, 2002; Bovee and Scott, 2002). Thus, increased sedimentation
alone may not generate suitable sandbar habitat unless a hydrologic
regime that suits colonization by cottonwood and willow trees is
allowed to occur.
4.0 LITERATURE AND DATA COLLECTION METHODOLOGY
Our approach to literature collection was to first conduct as
series of informational interviews with key personnel in the following
institutions:
--North Dakota Game and Fish
--United States Fish and Wildlife Service, Bismarck Office
--United States Geological Survey
--University of North Dakota
--North Dakota State University
--University of Nebraska
--United States Army Corps of Engineers, Omaha District
Through these interviews, we derived a list of the species to
evaluate in this section. We were also able to obtain key pieces of
literature that reviewed the life-cycle of key species in the State of
North Dakota.
The second step was to complete an Internet search using key terms
from species names and relying on search engines that investigated
government, academic, and professional Web sites. Through this
literature search we were able to obtain some reports (government or
academic) that described species of interest in States other than North
Dakota, if the in-State literature on a particular species was lacking.
The third step of literature collection involved searching through
Berger's extensive database of information on the ecology of the
Missouri River. Through our participation with other projects focused
on the Missouri River, Berger has assembled a large library of peer-
reviewed and government documents pertaining to various aspects of
ecology on the Missouri River. We were able to focus a search of this
library for literature that would provide information about the key
species in this analysis. This library was also useful in establishing
the basic ecological situation of the Missouri River and in
characterizing pre-regulation versus post-regulation characteristics
and conditions.
5.0 IDENTIFICATION AND DISCUSSION OF POTENTIAL SILTATION IMPACTS TO
FISH AND WILDLIFE
In this section we discuss the impacts of siltation to fish and
wildlife in the mainstem Missouri River in North Dakota, broken into
the two groups of species identified in Section 3.
5.1 Conservation Species
This group consists of seven fish, two reptiles, five birds, and
one mammal. All of these species have shown enough certainty of decline
for them to have been listed as species of conservation priority,
either at the State or national levels.
5.1.1. Fish
All of the seven fish are endemic to the Missouri River mainstem in
North Dakota. This means that they have evolved in a highly turbid
environment. For some species, declines in population have been
directly attributed to declines in water turbidity (flathead catfish,
all chubs, pallid sturgeon). While the general life-cycle
characteristics and habitat needs of these fish species is well-
established in the scientific literature, fish ecology in the North
Dakota portion of the Missouri River mainstem is not well-studied (Fred
Ryckman, 2008, personal communication; Chris Guy, 2008, personal
communication).
However, several ecological conditions are thought to impact the
health of conservation priority fish in the Missouri River mainstem in
North Dakota. For instance, there is enough information to conclude
that siltation has a positive impact on some species in some portions
of the river, but a negative impact on those same species when it
occurs elsewhere. This is especially true concerning fish reproduction.
Many of the conservation species are gravel spawners (paddlefish,
pallid sturgeon, blue sucker), and if gravel substrates become covered
with a layer of silt, these habitats become unsuitable for the fish
species (AFS, 2008). This is especially true in areas of the river with
low water velocity, such as the reservoirs, where silt may easily
settle out. In areas of high water velocity, however, it is less of a
problem because the high water velocity prevents the silt from settling
onto the gravel substrate (USFWS, 1993a).
The Williston reach currently does have high turbidity due to
sediment loads from the Yellowstone River, while the Garrison reach is
relatively deprived of sediment due to retention behind Garrison Dam
(Galat et al., 2005).
Blue Sucker
The blue sucker is a species of Level I conservation priority in
North Dakota. The species currently occupies Lake Oahe and the Garrison
reach. In addition, small populations have been found in the Williston
reach, but they do not appear to be reproducing successfully there. The
reasons for this are unclear (Fred Ryckman, 2008, personal
communication).
Blue suckers are adapted to live in the swift current of large,
turbid rivers (Hagen et al., 2005). Berry et al. (2004) found that blue
suckers used waters of 10 to 50 nephelometric turbidity units (NTUs) of
turbidity. They are mostly found in riffles and narrow chutes, and
require gravel bottoms free of sediment (Hagen et al., 2005).
Population decline over the years has been attributed to habitat
modification, specifically caused by temperature alteration and
turbidity reduction (Berry et al. 2004; Hagen et al., 2005). Population
recruitment \3\ has been observed in the Missouri River, however, blue
sucker reproduction has never been observed in the mainstem. As such,
it is likely that the young-of-year fish that add to the blue sucker
populations in the mainstem are spawned in the tributaries, after which
they migrate into the mainstem (Steven Krentz, 2008, personal
communication).
---------------------------------------------------------------------------
\3\ Recruitment is defined as ``the addition of new individuals to
a population by reproduction'' (Smith and Smith, 2008).
---------------------------------------------------------------------------
Increases in water turbidity in high-velocity reaches will likely
have a positive impact on this species. However, in waters of lower
velocity, an increased silt load may cause gravel substrates to become
covered by silt, resulting in a negative impact on blue sucker.
Flathead, Sicklefin, and Sturgeon Chubs
Sturgeon and sicklefin chubs are species of Level I conservation
priority according to the NDWAP, while flathead chubs are species of
Level II conservation priority.
All of these chubs are adapted for life in turbid, free-flowing
rivers with an abundance of sloughs, sandbars, and woody debris (Hesse,
1994, cited in Everett et al., 2004). Turbidity is a major variable
affecting sicklefin and sturgeon chub presence in rivers (USFWS, 2001;
Bonner and Wilde, 2002; Fisher et al., 2002; Everett et al., 2004).
Note that flathead chubs are more likely to use sandbar habitat than
sturgeon or sicklefin chubs (Fisher et al., 2002).
Reduced turbidity is likely the reason why chubs are no longer
found in the reservoirs of Lake Sakakawea or Lake Oahe, nor are they
found in the Garrison reach (Scarnecchia et al., 2002; Fred Ryckman,
2008, personal communication). Their presence has been observed in the
Williston reach, which retains pre-regulation levels of turbidity
(Scarnecchia et al., 2002).
As chubs are not currently known to inhabit the reservoirs, it is
difficult to determine whether increased sediment loading in these
reservoirs would serve to re-establish or support their populations.
Increased aggradation in the Garrison reach might be more likely to
have a positive impact on chubs, as this reach, though modified,
retains a riverine as opposed to lacustrine character. Particularly
given the positive association between chub presence and water
turbidity (USFWS, 2001; Bonner and Wilde, 2002; Fisher et al., 2002;
Everett et al., 2004), it is reasonable to predict that increases in
turbidity would have a positive impact on these fish, so long as this
occurs in an environment that is in all other respects inhabitable by
chubs. The reservoirs do not seem to meet this qualification, while the
Garrison reach does. However, scientific research on chub reproduction
in North Dakota is inadequate to fully assess how sedimentation will
affect their ability to reproduce successfully.
Flathead Catfish
Flathead catfish are an endemic species of Level III conservation
priority in the State of North Dakota. This species is known to use
pools with instream structure, such as snags, rubble, and bridge
supports (Berry et al., 2001). They are commonly found in waters with
high turbidity (USGS, 1998), and reproduce in holes along the river's
banks (Berry et al., 2001). Currently, the flathead catfish of North
Dakota are known to inhabit Lake Oahe exclusively, and are not found in
the other portions of the river in the State (Hagen et al., 2005).
The NDWAP cites reduced turbidity, temperature reduction, and
population fragmentation as reasons behind flathead catfish decline in
North Dakota (Hagen et al., 2005). Other studies have placed special
emphasis on the role of decreased turbidity in flathead catfish decline
(USGS, 1998; Berry et al., 2001). As such, increases in turbidity would
likely have a positive impact on this species, however, it is unknown
whether increased turbidity alone would be sufficient to restore and
support populations of this species and return it to the reaches from
which it has been expelled. Given its preference for slower waters
(Hagen et al., 2005), it may be unrealistic to expect flathead catfish
to return to areas of high-velocity flow, even if the turbidity in
these areas increases.
Paddlefish
This species is listed as a species of Level II conservation
priority. While it is legal to fish for paddlefish, given its
conservation status, the volume of the catch is subject to
restrictions.
Paddlefish do not rely on visual cues for spawning, migration, or
feeding (Firehammer et al., 2001), and typically grow successfully in
turbid environments. However, sedimentation poses a problem for
paddlefish egg-laying. Paddelfish spawn in the spring (Hagen et al.,
2005) and require clean, well-oxygenated gravel substrates in order to
deposit eggs successfully (Jennings and Zigler, 2000). Some research
suggests that paddlefish are particularly susceptible to losing their
spawning habitat as gravel substrates are covered with silt
(Sparks,1984, Turner and Rablais, 1991, Holland-Bartels, 1992, and
Schmulbach et al., 1992, cited in Jennings and Zigler, 2000). This is
likely a reason why they do not spawn in the Missouri River reservoirs,
where slow-moving currents cause suspended sediment to settle out and
cover gravel spawning beds (Fred Ryckman, 2008, personal
communication).
Hagen et al. (2005) note that the lower water velocity brought
about by the Missouri River reservoirs has allowed silt to cover
existing gravel substrates and make them unsuitable as reproductive
substrates for paddlefish. For this reason, paddlefish do not reproduce
within the Missouri River reservoirs. Most observed paddlefish
reproduction occurs in the Yellowstone River. Larvae produced in the
Yellowstone drift into the Williston reach, and eventually enter into
Lake Sakakawea (Scarnecchia et al., 2008; Fred Ryckman, 2008, personal
communication).
They do not reproduce successfully within the reservoir, yet adult
paddlefish are abundant in Lake Sakakawea. Paddlefish are also found in
Lake Oahe, however, scientists do not know where these fish originate
from (Fred Ryckman, 2008, personal communication).
Therefore, turbidity in high-velocity reaches such as the Williston
reach or in tributaries such as the Yellowstone River does not have an
adverse impact on paddlefish. As reproduction does not occur in the
reservoirs anyhow, increased turbidity in the reservoirs is not likely
to limit paddlefish populations because they can forage successfully in
turbid environments. Further research clarifying the importance of the
Garrison reach for paddlefish in North Dakota would clarify the
potential impacts of increased sedimentation in that area. Available
research suggests that increased turbidity in a high-velocity
environment benefits paddlefish.
Pallid Sturgeon
The pallid sturgeon was listed as a federally-endangered fish in
1990. In addition, they are a species of Level II conservation priority
in North Dakota.
Pallid sturgeon are morphologically adapted for benthic dwelling in
swift, turbid waters (Forbes and Richardson, 1905; Kallemeyn, 1983;
Gilbraith et al., 1988). They are known to use waters of 31.3 NTU (J.
Erickson, 1992, cited in USFWS, 1993b), and to have a current velocity
of 10 to 30 centimeters per second (J. Erickson, 1992, cited in USFWS,
1993b). Young-of-year and juvenile pallid sturgeon use sandbar habitat
(Yerk and Baxter, 2001, Kapuscinski and Baxter, 2003, and Doyle and
Starostka, 2003, cited in USFWS, 2003). Mostly they are found over sand
or gravel substrate (Sheehan et al., 2002 cited in USFWS, 2003; Hagen
et al., 2005). The population declines leading to their listing as a
federally-endangered species have been attributed to widespread habitat
destruction throughout their range (Gilbraith et al., 1988; Kallemeyn,
1983; NRC, 2002; USFWS, 2003, 2007).
Little is known about the pallid sturgeon's reproductive biology
(USFWS, 1993b; USFWS, 2003). It is thought that they spawn during July
and August (Forbes and Richardson, 1905) over hard rock, rubble, or
gravel substrate (USFWS, 2003). These characteristics are similar to
the well-studied shovelnose sturgeon (USFWS, 1993b).
Pallid sturgeon are known to spawn successfully in the relatively
unregulated Yellowstone River (Pat Braaten, 2008, personal
communication). However, no natural pallid sturgeon recruitment has
been observed in the Missouri River since monitoring began in earnest
approximately 20 years ago (Pat Braaten, 2008, personal communication;
Chris Guy, 2008, personal communication). Pallid sturgeon larvae are
known to drift close to the river-bottom (Braaten et al., 2008) and it
is hypothesized, though not empirically confirmed, that for this reason
larvae are suffocated and killed as they move into the sediment-laden
and slow-moving delta headwaters of Lake Sakakawea after drifting in
from the Yellowstone River (Pat Braaten, 2008, personal communication;
Fred Ryckman, 2008, personal communication).
The particular effects of siltation on pallid sturgeon are not well
understood, and would not be uniform across the Missouri River with its
diversity of flows, temperatures, and depths. Mitigation measures
dealing explicitly with sedimentation as it effects pallid sturgeon
have not been attempted in North Dakota (Chris Guy, 2008, personal
communication; Pat Braaten, 2008, personal communication).
Note that the declines in pallid sturgeon populations have been
attributed to habitat destruction throughout their range. This suggests
that neither the re-introduction of water turbidity, or increases in
siltation, are likely to suffice to restore their populations by
themselves.
5.1.2. BIRDS
Bald Eagle
The bald eagle was listed as a federally endangered species in
1967, but was delisted in 2007. It is a species of Level II
conservation priority in North Dakota.
Bald eagles build their nests in large trees. In North Dakota,
cottonwoods are particularly important nest trees and the majority of
bald eagles making use of the Missouri River mainstem and floodplain
habitat use cottonwood trees (Aron, 2005). They forage by perching in
trees and viewing the water in order to capture fish and waterfowl
(Steenhof et al., 1980).
Increases in water turbidity that prevent bald eagles from being
able to see fish in the water will cause bald eagles to turn to mammals
and birds for food (Grubb, 1995, cited in Stinson et al., 2007). So
long as mammal and bird prey is abundant, increased turbidity will not
have an impact on the foraging success of bald eagles.
If siltation increases the amount of fresh sandbars, it may lead to
an increase in cottonwood recruitment, which would benefit bald eagles.
Golden Eagle
The golden eagle is a species of Level II conservation priority in
North Dakota.
These birds usually nest on cliffs, but will also nest in
cottonwood or green ash trees (Hagen et al., 2005). They feed on small
animals, primarily mammals (Hagen et al., 2005). Current understanding
suggests that anthropogenic disturbance, caused by hunters, birders,
and manmade structures, in addition to toxic chemicals, are the biggest
threats to golden eagles. Habitat destruction is a problem not because
it reduces suitable habitat for golden eagles, but because it limits
access to food (Hagen et al., 2005).
If siltation increases the amount of cottonwood trees available by
creating more riparian habitat, it will have a positive impact on
golden eagles. Otherwise, it will not have a significant impact on
these birds.
Least Tern
The least tern was listed as a federally-endangered species in
1985. In addition it is a species of Level II conservation priority in
North Dakota.
The least tern adapted to colonial nesting on non-vegetated,
shifting sandbars within large, alluvial rivers (USFWS, 1990; USFWS,
2003). Dam operations have reduced the availability of this habitat for
least terns, due to the stabilizing effect on hydrology and their
tendency to trap suspended sediment necessary for sandbar formation
downstream (USFWS, 2003). According to USFWS (2000), the least tern's
range in North Dakota does not extend into Lake Sakakawea, but is
limited to the Garrison reach and Lake Oahe. Most research on least
tern habitat has been conducted on the lower Missouri River, not in
North Dakota (USACE, 2008).
Because the primary issue responsible for least tern decline is
reduced habitat availability caused primarily by sediment retention
behind dams, increased siltation would be a benefit for least terns
only if it is able to increase the amount of sandbar habitat available.
In the Garrison reach, which has a sediment deficit, increased
siltation would be particularly beneficial to least terns if it is able
to create sandbar habitat. Least terns require non-vegetated sandbar
habitat, so if fresh sandbars became colonized by vegetation then they
would be unsuitable for least tern use. This means that a one-time
sediment release would not create suitable habitat for least terns. The
generation of suitable sandbar habitat relies on the natural annual
hydrologic peaks, in addition to an unhindered supply of sediment,
occurring regularly as a constant flow through the system.
Piping Plover
The Northern Great Plains population of the piping plover (which
includes the entire North Dakota population of the species) was listed
as federally endangered in 1985. As of 2008, they had been changed from
a federally endangered species to a federally threatened species. This
bird is also a species of Level II conservation priority in North
Dakota.
Plovers use beach-like habitat, including sandflats and gravel,
with little vegetative cover (less than 20 percent). These habitats are
often adjacent to rivers and reservoirs; they can also use natural
islands that meet these characteristics (Haig, 1992). Northern Great
Plains piping plovers in the pre-regulation Missouri River nested on
sandbars and islands (Galat, 2005; Haig et al., 1994). They feed
primarily on terrestrial invertebrates and benthic worms (Haig, 1992).
Siltation will benefit piping plovers if it occurs in high-velocity
currents where it may aggrade to form sandbars and islands. As with the
least tern, piping plovers require non-vegetated sandbars, and so any
sandbar habitat that is formed will be unsuitable if it becomes
colonized by vegetation. Siltation that does not generate sandbar
habitat will not affect piping plovers. Thus, as with the least tern, a
one-time release of sediment will not suffice to restore sandbar
habitat suitable for piping plover. Sandbar habitat will require
hydrologic peaks and flows that would transport sediment through the
system.
Red-Headed Woodpecker
The red-headed woodpecker is a species of Level II conservation
priority in the State of North Dakota.
Red-headed woodpeckers live in deciduous woodlands in the upland or
floodplain habitats (Hagen et al., 2005). They make nests anywhere from
5 to 80 feet above ground level, in dead oak, ash, maple, elm,
sycamore, cottonwood, or willow trees, or in utility poles (Hagen et
al., 2005). Their diet is composed of insects found in decaying wood,
corn, nuts, berries, and occasionally the eggs or young birds of other
passerines (Hagen et al., 2005).
Siltation will not have an impact on red-headed woodpecker, unless
it generates an increase in tree recruitment, which would have a
positive impact.
5.1.3. OTHER CONSERVATION SPECIES
False Map Turtle
The false map turtle is a species of Level III conservation
priority in North Dakota.
False map turtles rely primarily on large rivers and backwaters for
their habitat (Bodie et al., 2000). Their decline has been attributed
to the reduction and alteration of sandbar habitat in the mainstem
Missouri River (Hagen et al., 2005). Therefore, siltation will benefit
false map turtles if it generates new sandbar habitat. Recall from the
discussions on least tern and piping plover that a one-time release of
sediment will not suffice to this end.
Smooth Softshell Turtle
The smooth softshell turtle is a species of Level III conservation
priority in North Dakota.
Smooth softshell turtles rely primarily on moderate to fast streams
and rivers (Bodie et al., 2000). They are found in Lake Oahe, but have
not been observed in Lake Sakakawea, nor have they been observed in the
Garrison or Williston reaches of the river (Hagen et al., 2005).
North Dakota's 2005 Wildlife Action Plan suggests that reductions
in sandbar habitat have been the primary cause of smooth softshell
turtle declines. Therefore, siltation that results in the generation of
sandbar habitat will be beneficial to these reptiles.
River Otter
The river otter is a species of Level II conservation priority in
North Dakota.
River otters historically occurred throughout aquatic habitats in
North Dakota, but their populations have declined due to the
destruction or modification of riparian habitat, usually for the
purposes of economic development of various kinds, including
agricultural, residential, or others (Hagen et al., 2005). The current
status of river otter populations in North Dakota is uncertain, and it
is not clear whether a viable population exists within the State.
However, we include river otters in our analysis because the Missouri
River is an important waterway through which these animals might return
to North Dakota from populations in other States (Hagen et al., 2005).
Increased siltation will only affect river otters if it generates
riparian habitat, as they are known to use this habitat. Decline in
riparian and wetland habitat was cited in Hagen et al. (2005) as a
reason for river otter decline.
5.2 RECREATIONAL SPECIES
Walleye, channel catfish, sauger, northern pike, white bass, and
Chinook salmon are the most important recreational fish species on the
Missouri River in North Dakota. Of these six fish species, walleye are
the most prized recreation fish. The fisheries for all of these species
are thriving under the current sediment regime, although the particular
impacts of siltation on the most popular species such as walleye,
sauger, and northern pike remain unclear (Fred Ryckman,2008, personal
communication). Trapping and hunting occurs for Canada goose, beaver,
and muskrat (Steve Dyke, personal communication, 2008), so we include
these animals as well. The methods used to estimate the populations of
the recreational fish species are outlined in Brooks et al. (2007a,
2007b). Note that the margin of error is likely due to a small sample
size.
Academic and government studies reveal that endemic recreational
fish that were abundant in the pre-regulation Missouri River benefit
from the increased turbidity brought about by siltation; these include
the channel catfish and the sauger.
For those fish that were introduced or that were artificially made
abundant, the effects of an increased sediment load and increased
turbidity are negative; in this group are the northern pike, white
bass, Chinook salmon, and walleye. Increases in sediment load are
thought to be detrimental to these species for two reasons. First,
these species are all visual predators, and their foraging success
decreases in turbid waters. Second, their reproductive success requires
a rocky or gravel substrate for laying eggs, and if this is coated with
a layer of sediment, it becomes unsuitable. Highly-aggraded habitat is
therefore unsuitable for them.
Fisheries for walleye exist in all four segments of the Missouri
River mainstem in North Dakota. The considerable sedimentation that
does occur in the inter-reservoir reaches presumably affects them, but
successful fisheries exist nonetheless. The sediment-laden waters of
the Williston reach deposit their sediment load in the 61-kilometer
delta of Lake Sakakawea. The reservoir beyond the delta is relatively
clear. Thus, increased siltation in the Williston reach or in the Lake
Sakakawea delta will only affect the Lake Sakakawea fishery if it is of
a volume sufficient to significantly increase the length of the delta
or to increase the turbidity and siltation of the clear waters beyond
the delta. For this reason, siltation in the inter-reservoir reaches
will not have an impact on the fishery species unless it is severe.
Recall, however, that much about the effects of siltation on fishery
species remains uncertain (Fred Ryckman, 2008, personal communication);
what is known is that the current conditions allow these species to
thrive (Brooks et al., 2007a, 2007b; Fred Ryckman, 2008, personal
communication).
Walleye
Walleye are a native fish in the Missouri River basin, although
prior to the construction of dams, they were not abundant (Benson,
1968, cited in Bryan, 1995).
Today, walleye are the major constituent of the recreational
fishery on the Missouri River in North Dakota. Eighty-two percent of
the anglers on Lake Oahe in 2006 were found to fish primarily for
walleye (Brooks et al., 2007a). Walleye accounted for 98 percent of
boat angling and 68 percent of shore angling in 2006 on Lake Sakakawea
(Brooks et al., 2007b). Total harvest of walleye from Lake Sakakawea
during 2006 was between 993,482 and 285,871 fish caught by boat
anglers, and between 476,051 and 181,468 fish caught by the shore
anglers (Brooks et al., 2007b). In Lake Oahe, boat anglers caught
between 141,951 and 48,719 individual walleyes, while shore anglers
caught between 110,344 and 45,125 individuals (Brooks et al., 2007a).
Walleye are visual predators, and as such, high turbidity may
impair their ability to see their prey and thus to forage successfully.
They are also opportunistic predators that prey on a variety of fish
species (Lyons and Magnuson, 1987, Vigg et al., 1991, Jackson, 1992,
and Mero, 1992, cited in Bryan, 1995), and during portions of the year,
their diet may consist primarily of aquatic insects (Kelso, 1973;
Swenson, 1977, Johnson et al., 1988, and Mero, 1992, cited in Bryan,
1995). The most important prey fish are rainbow smelt, spottail shiner,
and freshwater drum (Jackson, 1992, cited in Bryan, 1995). With the
exception of freshwater drum, these species were introduced to the
Missouri River system as forage for walleye and other game fish (Galat
et al., 2004). They are not adapted to life in a turbid environment.
Thus, increased turbidity in the clear waters of the reservoirs may
have a negative impact on these fish, and these effects may carry over
to walleye.
Siltation also has implications for walleye reproduction. This is
because walleye are broadcast spawners, releasing fertilized eggs into
the water column over a rocky surface so that they descend into the
cracks between rocks and later hatch (Kerr et al., 1997, cited in
Dustin and Jacobson, 2003). They have also been observed laying eggs
over live vegetation (Dustin and Jacobson, 2003). Eggs that land on
sand, silt, or muck experience high mortality (Johnson, 1961, and
Priegel, 1970, cited in Dustin and Jacobson, 2003). Therefore, if the
rocky surfaces that walleye rely on for reproduction become covered by
sediment, this reduces their ability to reproduce successfully.
Siltation of a level sufficient to prevent aquatic plant growth will
also reduce walleyes' ability to reproduce successfully over
vegetation.
Another way in which sediment will affect walleye is in its
capacity to modify temperature. Temperature is an extremely important
factor in walleye growth (Armour, 1993, cited in Bryan, 1995), and they
cannot reproduce in waters colder than 6 C (Hokanson, 1977, cited in
Bryan, 1995). If the suspended sediment load reduces the water
temperature below this level during spawning, it will reduce their
population.
The Williston and Garrison reaches have walleye fisheries, and
these occur during late summer through spring, which are clear-water
periods (NDGF, 1998a, 1998b).
Thus because of effects on foraging and reproduction, increased
siltation is likely to have a negative effect on walleye populations.
However, the walleye fishery in Lakes Sakakawea and Oahe is thriving.
This is true of Lake Sakakawea despite the sediment load from the
Williston reach and the delta at the headwaters. The effects of
siltation on walleye in North Dakota are unclear (Fred Ryckman, 2008,
personal communication). However, under current conditions their
populations are not declining. Increased sediment loads are not likely
to be a problem for walleye unless they result in increased turbidity
in the clear waters of Lakes Sakakawea and/or Oahe.
Northern Pike
On Lake Sakakawea in 2006, northern pike accounted for less than 1
percent of all boat angling efforts, and 8 percent of all shore angling
efforts, representing 7,799 (+/- 23,305) and 1,116 (+/- 6,737)
individual fish, respectively (Brooks et al., 2007b). On Lake Oahe,
northern pike accounted for less than 1 percent of all boat angling
efforts, and 3 percent of all shore angling efforts (Brooks et al.,
2007a). These totals (1,884 (+/- 4,674) and 636 (+/- 2,951),
respectively) are for individual fish (Brooks et al., 2007a).
Northern pike thus constitute an important recreational species,
and much of their life-cycle needs are similar to those of walleye.
They are visual predators (Polyak, 1957, and Braekvelt, 1975, cited in
Inskip, 1982), therefore increases in water turbidity affects their
ability to detect prey and to forage successfully. Although northern
pike will eat a variety of small mammals including invertebrates,
waterfowl, and small mammals, they are mostly piscivorous,\4\ with
gizzard shad, alewife, yellow perch, and trout-perch comprising the
bulk of their diet (Inskip, 1982). Ambush constitutes a major foraging
strategy for northern pike; as such, they require aquatic plants for
cover. Siltation reduces aquatic plant cover (by choking out young
plants or by reducing light penetration); therefore, it will have a
negative impact on northern pike.
---------------------------------------------------------------------------
\4\ A piscivore is a carnivorous animal which lives on eating fish.
---------------------------------------------------------------------------
Northern pike spawn over vegetation in areas of calm, shallow water
(Williamson, 1942, and Clark, 1950, cited in Inskip, 1982). They can
use flooded terrestrial vegetation for this purpose, although they have
been observed using backwaters (McCarraher and Thomas, 1972, Jarvenpa,
1962a, and Frost and Kipling, 1967, cited in Inskip, 1982). Therefore,
a reduction in submerged vegetation brought about by siltation reduces
the northern pike's ability to spawn successfully.
The Williston and Garrison reaches have northern pike fisheries
occurring during late summer through spring, which are clear-water
periods (NDGF, 1998a, 1998b).
If siltation or turbidity increases occur in the clear waters of
Lakes Sakakawea and/or Oahe, they will have a negative impact on
northern pike populations due to adverse effects on foraging and
reproduction. However, increased siltation in the Williston or Garrison
reaches will not likely have an impact on northern pike, because unless
it is severe, such siltation aggrades in the reservoir deltas once it
reaches the reservoir from the inter-reservoir reach. This would leave
ample clear-water areas in the reservoir for the northern pike fishery
to remain.
Channel Catfish
In Lake Sakakawea during 2006, only 438 channel catfish were caught
by shore and boat anglers (Brooks et al., 2007b). However, on Lake
Oahe, channel catfish accounted for 3 percent of all boat angling
efforts, and 39 percent of all shore angling efforts (Brooks et al.,
2007a). Brooks et al. (2007a) estimate that 13,346 (+/- 16,857) channel
catfish were caught by boat anglers, and 6,872 (+/- 13,571) channel
catfish were caught by shore anglers.
Channel catfish are a native species throughout the Missouri River
basin (Galat et al., 2004), and are substrate generalists (Pegg and
Pierce, 2002). They use habitat in the mainstem, in the floodplain, and
in reservoirs (Galat et al., 2004). They feed on insects and
crustaceans (Walburg, 1975). Channel catfish in turbid water fisheries
do not require stocking, and natural recruitment serves to maintain
their population (Mosher et al., 2006), suggesting that they can
successfully exist in turbid environments.
Because channel catfish are known to thrive in turbid environments,
increases in turbidity are likely to have a positive impact on their
populations in the Missouri River in North Dakota.
Chinook Salmon
Chinook salmon are a non-native species in the Missouri River
system.
During 2006, Chinook salmon accounted for 1 percent of all boat
angling, and 8 percent of all shore angling on Lake Sakakawea (Brooks
et al., 2007a). The totals (4,199 (+/- 6,268) and 3,907 (+/- 5,806),
respectively) are for individual fish (Brooks et al., 2007b). On Lake
Oahe during 2006, only 1,121 Chinook salmon were caught (Brooks et al.,
2007a).
Chinook salmon lay their eggs over a gravel substrate (Rice, 1960,
cited in McCullough, 1999). Therefore gravel that becomes covered by
sediment is unsuitable as spawning ground for Chinook salmon. However,
Chinook salmon do not reproduce naturally in the Missouri River in
North Dakota, and their population is entirely the result of stocking
efforts; therefore, siltation will not affect their ability to
reproduce. Additionally, turbidity has been shown to reduce the growth
of the closely-related coho salmon (Sigler et al., 1984). As the
Chinook salmon's popularity as a sport fish in Lake Sakakawea reflects
a general abundance of this species in that reservoir, we may infer
that the lack of siltation in Lake Sakakawea is favorable to Chinook
salmon.
Thus, due to the limitations that it places on growth and on
spawning, siltation is likely to have negative impacts on Chinook
salmon. Increased siltation in the reservoirs is likely to have a
negative impact on the species for the reasons outlined above.
Increased siltation in the Williston reach is not likely to affect them
unless it is severe enough to significantly increase the size of the
delta or the turbidity of waters in Lake Sakakawea. Increased siltation
in the Garrison reach is not likely to affect Chinook salmon in an
appreciable way.
Sauger
Sauger accounted for 2 percent of all boat angling and 4 percent of
all shore angling on Lake Oahe during 2006, representing 3,940 (+/-
9,923) and 2,209 (+/- 7,031) individual fish, respectively (Brooks et
al., 2007a). On Lake Sakakawea in 2006, sauger accounted for 1 percent
of all boat angling and less than 1 percent of all shore angling,
representing 8,363 (+/- 21,394) and 4,588 (+/- 12,654) individual fish,
respectively (Brooks et al., 2007b). The Williston reach has a sauger
fishery as well (NDGF, 1998a).
Sauger prefer habitat with high physical turbidity (Pflieger, 1975;
Graeb, 2006). Therefore, other factors being equal, it is possible that
increases in water turbidity will increase the likelihood of sauger
presence. Little is known about sauger reproduction, and so siltation's
effect thereupon cannot be estimated accurately here. However, it is
known that sauger spawn successfully in the Lewis & Clark Lake delta of
Nebraska. Therefore, it is possible that an increase in delta habitat
brought about by siltation will have a positive impact on sauger
reproduction (Graeb, 2006). Regardless, the current sediment regime
allows for productive sauger fisheries throughout the Missouri River in
North Dakota (NDGF, 1998a, 1998b; Brooks et al., 2007a, 2007b).
Gizzard shad are an important prey species for sauger (Graeb,
2006). Therefore, siltation will affect sauger in accordance with its
effects upon gizzard shad. As gizzard shad are native to the Missouri
River mainstem (Galat et al., 2004), it is unlikely that turbidity and
high sediment loads have a negative effect upon their populations, so
increases in siltation are not likely to affect them.
Siltation is likely to have a positive effect on sauger populations
because is improves foraging habitat. However, the sauger fishery is
currently thriving in the clear, silt-free waters of Lakes Sakakawea
and Oahe.
White Bass
In 2006 on Lake Sakakawea, a total of 1,425 white bass were caught
by boat and shore anglers (Brooks et al., 2007b). During the same year
on Lake Oahe, white bass accounted for 1 percent of all boat angling
efforts, and 4 percent of all shore angling efforts (Brooks et al.,
2007a). The totals (2,308 (+/- 6,880) and 945 (+/- 5,821),
respectively) are for individual fish (Brooks et al., 2007a).
White bass were introduced into the Missouri River in 1959, 1960,
and 1961 (Ploskey et al., 1994, cited in Beck, 1998). White bass are
visual predators and feed on zooplankton in the early life stages and
then their diet turns to fish and insects as growth progresses
(Michaletz et al., 1977, cited in Beck, 1998). Juvenile white bass are
prey for walleye, and have been known to seek cover from these fish in
stands of aquatic vegetation (Beck, 1998).
Increased turbidity would have a negative impact on white bass
because it would reduce their ability to forage successfully. Also,
siltation that reduces aquatic vegetation will reduce the amount of
cover available for juvenile white bass, so predation may increase,
further reducing population size.
Canada Geese
Canada geese are opportunistic nest-builders, using whatever
materials they can find, and build nests near open water with low banks
(Dewey and Lutz, 2002). If no vegetation is present, Canada geese may
construct nests in the open, simply by depressing the ground with their
body weight and laying eggs into it (Dewey and Lutz, 2002). These birds
feed on grasses, and can be quite flexible in their diet (Dewey and
Lutz, 2002).
Siltation is not likely to affect Canada geese unless it reduces
the amount of low-bank habitat, which is itself unlikely because silt
deposition would create shallow-water habitat that suits Canada geese.
Silt deposition might reduce herbaceous vegetation, reducing the food
available for Canada geese.
Muskrat
Muskrats are present on the Missouri River system in North Dakota,
and rely on riparian habitat for nesting and foraging (Smith, 1996).
They create burrows in the river's banks, which can disturb sediment
and result in increased turbidity (McMasters University, 2008).
Muskrats feed primarily upon riparian plants, but consume mollusks and
crustaceans occasionally (Natureserve, 2008).
Increased siltation of the mainstem Missouri River will not affect
muskrats unless it significantly affects the amount of riparian
vegetation that is available as food. As these animals naturally
generate increases turbidity through their burrowing activities, it is
not likely that increased turbidity brought about by large sediment
loads will have a negative impact on them.
Beavers
Beavers are known for building their own stream impoundments, which
can alter the riverine landscape; however, the Missouri River
mainstem's large size and great depth prevents beavers from building
impoundments on it, and so they instead burrow into the banks and
create underwater food caches there (Collen and Gibson, 2001). While
beaver dams may bring about a reduction in water velocity and thereby
reduce the sediment carrying capacity of a stream, the absence of
beaver dams on the Missouri River mainstem prevents this from
happening. Beavers feed on riparian plants (Andersen and Cooper, 2000;
Collen and Gibson, 2001).
Siltation will not affect beavers unless it affects the abundance
of riparian plants that may constitute part of the beavers' forage
base.
6.0 CONCLUSIONS
The results of our analysis are summarized below and in Table 1.
Increased sediment loads are likely to have a positive impact on
channel catfish and sauger, which are known to inhabit turbid waters.
These fish are not currently species of conservation priority, and the
current sediment regime is allowing them to sustain populations.
Siltation will have no significant impact upon river otters and
Canada geese. These animals are not directly affected by turbidity.
Moreover, the reasons for the decline in river otter populations are
the complete removal of habitat and changes in siltation will not
significantly affect this factor. Canada geese are opportunistic in
their habitat use; however, for the reasons noted in Section 6.2.1,
Canada geese may be affected by increased siltation, although this is
unlikely.
Siltation will have a positive impact on red-headed woodpeckers,
golden eagles, and bald eagles only if it increases the amount of
riparian forest habitat available, other wise it will have no impact.
These birds all require riparian forests for their habitat. Siltation
may contribute to riparian forest habitat by aggrading and creating new
surfaces for colonization by cottonwoods and willows, but in the
absence of natural hydrology this is unlikely to occur.
Increased sediment loading occurring in the clear waters of
reservoirs will have a negative impact upon walleye, northern pike,
Chinook salmon, and white bass. These species are all visual predators
and gravel spawners, and increased turbidity and increased siltation
has negative consequences for them. The current sediment regime does
allow for an abundant fishery throughout the Missouri River in North
Dakota. Note that inter-reservoir fisheries for these fish species
exist only during clear-water seasons (late summer through spring;
NDGF, 1998a, 1998b).
The pallid sturgeon, paddlefish, flathead chub, sicklefin chub,
sturgeon chub, and blue sucker are adapted to thrive in a highly turbid
environment, but cannot be expected to increase in abundance unless
other environmental factors are satisfied also. The pallid sturgeon, as
discussed above, is adapted to life in a turbid environment, however,
they do not reproduce successfully in any reaches of the Missouri
River, even the turbid Williston reach. It is hypothesized that their
larval drift habits, which involve larvae drifting close to the river
bottom, causes them to undergo widespread mortality after they reach
deltas. The paddlefish can grow in the Missouri River, but do not
reproduce successfully in any reach. It is known that chubs require
turbid water for their survival, but it is unclear whether this is the
only reason why they do not inhabit Lakes Sakakawea or Oahe. The blue
sucker does indeed exist in the reservoirs, but primarily it inhabits
the inter-reservoir reaches.
The least tern, piping plover, smooth softshell turtle, and false
map turtle require sandbar habitat, and siltation that increases
sandbar habitat will be of benefit to them. Sandbar habitat is more a
result of hydrology than of sediment load. Therefore, NDGF (1998a,
1998b) recommends that flows be managed to allow more sandbar habitat
to be created in the inter-reservoir reaches. NDGF, 1998a, suggests
that ``[i]n at least one year out of four, sustained flows of less than
28,000 but greater than 40,000 cfs in April, May, and June [would be]
sufficient to create and/or scour sandbars for terns and plovers'' (p.
3). Also, in order to be suitable habitat for terns and plovers,
sandbars must be free of vegetation; USACE has not had complete success
in managing sandbar habitat to be free of vegetation (USACE, 2008),
although further research into feasible techniques is planned for the
near future (USACE, 2008).
TABLE 6-1.--IMPACT OF SILTATION ON KEY SPECIES
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Positive impact if
siltation increases Siltation positive, Positive impact if
Positive impact No significant riparian forest Negative impact but require other siltation increases River sections that the
impact habitat; otherwise environmental sandbar habitat animal predominates in
no impact factors as well
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Conservation Priority Level I:
Blue sucker........................ ................... ................... ................... ................... X ................... Oahe and Garrison
Sturgeon chub...................... ................... ................... ................... ................... X ................... Williston only
Sicklefin chub..................... ................... ................... ................... ................... X ................... Williston onlyConservation Priority Level II:
Bald eagle......................... ................... ................... X ................... ................... ................... N/A
Golden eagle....................... ................... ................... X ................... ................... ................... N/A
Least tern......................... ................... ................... ................... ................... ................... X N/A
Piping plover...................... ................... ................... ................... ................... ................... X N/A
Red-headed woodpecker.............. ................... ................... X ................... ................... ................... N/A
River otter........................ ................... X ................... ................... ................... ................... N/A
Flathead chub...................... ................... ................... ................... ................... X ................... Williston Reach only
Paddlefish......................... ................... ................... ................... ................... X ................... Williston, Sakakawea,
Oahe
Pallid sturgeon.................... ................... ................... ................... ................... X ................... Yellowstone River and
WillistonConservation Priority Level III:
Smooth softshell turtle............ ................... ................... ................... ................... ................... X N/A
False map turtle................... ................... ................... ................... ................... ................... X N/A
Flathead catfish................... ................... ................... ................... ................... X ................... Oahe onlyRecreational Species:
Beaver............................. ................... ................... ................... ................... ................... ................... N/A
Canada goose....................... ................... X ................... ................... ................... ................... N/A
Channel catfish.................... X ................... ................... ................... ................... ................... Oahe
Chinook salmon..................... ................... ................... ................... X ................... ................... Sakakawea
Muskrat............................ ................... ................... ................... ................... ................... ................... N/A
Northern pike...................... ................... ................... ................... X ................... ................... Sakakawea
Sauger............................. X ................... ................... ................... ................... ................... Sakakawea, Oahe
Walleye............................ ................... ................... ................... X ................... ................... Sakakawea, Oahe
White bass......................... ................... ................... ................... X ................... ................... Sakakawea, Oahe
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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Missouri and lower Yellowstone rivers in relation to flow
characteristics. Hydrobiologia 479: 155-167.
Pflieger, W.L. 1975. The fishes of Missouri. Missouri Department of
Conservation, Jefferson City. 343 pp.
Richkus, K.D., K. A. Wilkins, R.V. Raftovich, S.S. Williams, and
H.L. Spriggs. 2008. Migratory bird hunting activity and harvest during
the 2006 and 2007 hunting seasons: Preliminary estimates. U.S. Fish and
Wildlife Service. Laurel, Maryland. USA.
Rood S., Braante J., Hughes F. Ecophysiology of riparian
cottonwoods: stream flow dependency, water relations and restoration.
Tree Physiology 23, 1113-1124. 2003.
Ryckman, F. 2000. The Confluence. North Dakota Outdoors 63: 8-10.
Scarnecchia, D., S. Everett, T. Welker, and F. Ryckman. 2002.
Missouri River Fishes: Big Changes in the Big Muddy. North Dakota
Outdoors 10-13.
Schmulbach, J.C., G. Gould, and C.L. Groen. 1975. Relative
abundance and distribution of fishes in the Missouri River, Gavins
Point Dam to Rulo, Nebraska. Proceedings South Dakota Academy of
Science 54: 194-222.
Smith, J.W. 1996. Wildlife Use of the Missouri and Mississippi
River Basins. In Galat, D.L., and Frazier, A.G. (eds.), Overview of
River-Floodplain Ecology in the Upper Mississippi River Basin. Volume 3
of Kelmelis, J.A. (ed.), Science for Floodplain Management into the
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111.
Sigler, J.W., T.C. Bjornn, and F.H. Everest. 1984. Effects of
Chronic Turbidity on Density and Growth of Steelheads and Coho Salmon.
Transactions of the American Fisheries Society 113: 142-150.
Sluis, W., and J. Tandarich. 2004. Siltation and hydrologic regime
determine species composition in herbaceous floodplain communities.
Plant Ecology 173: 115-124.
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Stinson, D.W., J.W. Watson, and K.R. McAllister. 2007. Status
Report for the Bald Eagle. Washington Department of Fish and Wildlife,
Olympia. 86 + viii pp.
United States Army Corps of Engineers (USACE). 2008. Draft
Environmental Assessment for the Restoration of Emergent Sandbar
Habitat Complexes in the Missouri River; Nebraska and South Dakota.
U.S. Army Corps of Engineers, Omaha District. 78 pp.
USFWS. 2007. Pallid Sturgeon (Scaphirhynchus albus), 5-Year Review
Summary and Evaluation. U.S. Fish and Wildlife Service Pallid Sturgeon
Recovery Coordinator, Billings, MT.
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to the 2000 Biological Opinion on the Operation of the Missouri River
Main Stem Reservoir System, Operation and Maintenance of the Missouri
River Bank Stabilization and Navigation Project, and Operation of the
Kansas River Reservoir System.
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of Sturgeon and Sicklefin Chub in the United States. United States
Department of the Interior. 80 pp.
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Blue Sucker (Cycleptus elongatus), a Candidate Endangered or Threatened
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albus). U.S. Fish and Wildlife Service, Bismark, North Dakota. 55 pp.
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Department of Zoology, University of Toronto.
appendix f--impact of siltation on flood control missouri river, north
dakota
1.0 INTRODUCTION
The Louis Berger Group, Inc. (Berger) was tasked by the U.S. Army
Corps of Engineers (USACE) to assess the potential impacts of
sedimentation in the Missouri River within the State of North Dakota.
The assessment was to be based on review of relevant existing data and
information. The study area was defined by the USACE to include the
watershed of the mainstem of the Missouri River from the North Dakota/
South Dakota border on the downstream end to the Montana/North Dakota
border on the upstream end. This section of the report analyzes the
potential impacts of sedimentation on flood control.
The Garrison and Oahe Dams and their respective reservoirs are part
of the Missouri River Mainstem System consisting of six dams in total.
The Garrison and Oahe Dams were authorized by the Flood Control Act and
serve as the main mechanisms for flood control along the Missouri River
in the State of North Dakota.
1.1 Principal Flood Problems
Principal flood problems were identified in the 2005 Flood
Insurance Study (FIS) prepared by the Federal Emergency Management
Agency (FEMA) for the Bismarck, North Dakota area. The FIS attributes
the following four conditions as the causes or contributing factors to
flooding in the area: (1) open-water season flooding from Garrison Dam
operations; (2) open-water season flooding from tributaries, and other
residual drainage areas below Garrison Dam, combined with releases from
Garrison Dam; (3) flooding, resulting from ice jams and ice conditions;
and (4) flooding caused by aggradation in the upper reaches of the Lake
Oahe.
Major flooding along the Missouri River occurred in 1881, 1887,
1910, 1917, 1938, 1939, 1943, 1947, 1950 and 1952. As a result of the
completion of Garrison Dam in 1953, floods of the magnitudes
experienced during these events would have a recurrence interval
greater than 500 years.
The maximum peak discharge that has occurred since 1953 on the
Missouri River was 68,900 cubic feet per second (cfs) at the USGS
stream gage at the city of Bismarck. This occurred on July 13, 1975,
with an estimated recurrence interval of 75 years. A more recent flood
of record occurred in May 1980, with a peak discharge of 18,900 cfs.
The highest record of flooding at the Bismarck stream gage since
completion of the Garrison Dam was 14.8 feet, which occurred on January
13, 1983, because of ice conditions and ice jams. A discharge of 59,500
cfs was recorded on July 25, 1997. These conditions are typical of an
event with a recurrence interval of approximately 10 years.
1.2 Flood Storage Capacity Losses in Reservoirs
The Garrison and Oahe Reservoirs have defined zones for flood
control, multiple uses, and permanent pool. These zones are defined as
follows and are shown on Figure 1-1:
--Exclusive Flood Control Zone.--This zone is the total upper volume
of the mainstem lakes maintained exclusively for flood control.
Water is released from this zone as quickly as downstream
channel conditions permit so that sufficient storage remains
available for capturing future inflows.
--Annual Flood Control and Multiple Use Zone.--This zone is used to
store the high annual spring and summer inflows to the
reservoirs. Later in the year, water stored in this zone is
released for riverine uses so that the zone is evacuated by the
beginning of the next flood season on March 1. Evacuation is
accomplished mainly during the summer and fall navigation
season.
--Carryover Multiple Use Zone.--This zone is designed to provide
water for all uses during drought periods. The zone is operated
so that it remains full during periods of normal inflow but is
gradually drawn down during drought periods.
--Permanent Pool.--The permanent pool provides the minimal water
level necessary to allow the hydropower plants to operate and
to provide reserved space for sediment storage. It also serves
as a minimum pool for recreation and for fish and wildlife
habitat and as an ensured minimum level for pump diversion of
water from the reservoirs.
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 1-1.--Reservoir Storage Zones
The Garrison Reservoir has lost 907,000 acre-feet of total storage
capacity due to accumulated sediments from the time it began operation
in 1953 until 1988. The Oahe Reservoir has lost 614,000 acre-feet of
total storage capacity from the time it began operation in 1958 until
1989. Table 1-1 and Figure 1-2 show the storage loss by zone.
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 1-2.--Reservoir Storage Losses By Zone
TABLE 1-1.--RESERVOIR STORAGE LOSSES BY ZONE
--------------------------------------------------------------------------------------------------------------------------------------------------------
Total Storage Below the Pool Storage Change Over Time (percent)
Elevation (1,000 acre-feet) -----------------------------------------------------------------------
---------------------------------------
Flood Flood Carryover Total Total
Year Excl. Control Carryover Excl. Control & Perm. Storage Storage Annual
Flood & & Perm. Flood & Multiple Pool Loss Loss Loss
Control Multiple Multiple Pool Control Multiple Use 1,000 (percent) (percent)
Use Use Use acre-ft
--------------------------------------------------------------------------------------------------------------------------------------------------------
Garrison Reservoir:
Pool Elev............................ 1,854 1,850 1,837.5 1,775 1,854 1,850 1,837.5 1,775 ....... ......... .........
1953............................. 24,728 23,225 18,917 5,152 ........ ........ ......... ........ ....... ......... .........
1958............................. 24,504 23,000 18,694 5,004 -0.1 ........ 0.5 2.9 224 0.9 0.18
1959............................. 24,477 22,973 18,670 4,989 -0.1 0.1 0.6 3.2 251 1.0 0.17
1964............................. 24,355 22,846 18,517 4,981 -0.4 -0.5 1.7 3.3 373 1.5 0.14
1969............................. 24,137 22,635 18,348 4,976 0.1 0.5 2.9 3.4 591 2.4 0.15
1979............................. 23,923 22,439 18,209 4,990 0.6 2.0 4.0 3.1 805 3.3 0.13
1988............................. 23,821 22,332 18,110 4,980 0.9 2.0 4.6 3.3 907 3.7 0.11
Oahe Reservoir:
Pool Elev............................ 1,620 1,617 1,607.5 1,540 1,620 1,617 1,607.5 1,540 ....... ......... .........
1958............................. 23,751 22,649 19,490 5,665 ........ ........ ......... ........ ....... ......... .........
1963............................. 23,647 22,545 19,386 5,575 ........ ........ 0.1 1.6 104 0.4 0.09
1968............................. 23,507 22,416 19,239 5,521 1.0 -0.6 0.8 2.5 244 1.0 0.10
1976............................. 23,337 22,240 19,054 5,451 0.5 -0.9 1.6 3.8 414 1.7 0.10
1989............................. 23,137 22,035 1,883 5,373 ........ -1.3 2.6 5.2 614 2.6 0.08
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: Aggradation, Degradation and Water Quality Conditions, USACE 1993.
Data taken from Plate 7, ``Summary of Reservoir Surveys and Associated Storage Loss by Zone''.
2.0 LITERATURE AND DATA COLLECTION METHODOLOGY
Jeff Klein of the North Dakota State Water Commission (NDSWC) was
contacted to obtain data used to develop the Missouri River hydraulic
model, particularly channel profile data. Mr. Klein responded by
providing components of the hydraulic model in Burleigh and Morton
Counties.
Nancy Steinberger, the Regional Engineer for FEMA was contacted to
obtain historic flood plain mapping and historic hydraulic modeling of
the river, particularly the channel profiles from the model input data
set. Ms. Steinberger indicated that the channel profiles of the river
would best be obtained from the Omaha District of the USACE, who was
responsible for the hydraulic modeling. Ms. Steinberger further
indicated that historic flood mapping of the Missouri River in North
Dakota could be obtained through FEMA but only three counties, Morton,
Burleigh, and a small portion of Williams, have been updated in recent
years. She noted that the Williams County update was underway and had
not been published yet. Morton, Burleigh and Williams County (in the
vicinity of the town of Williston) were updated because they contain
population centers; the other counties along the Missouri River within
the State of North Dakota did not have populations high enough to
warrant updating the FEMA mapping.
Due to the lack of new flood data all along the Missouri River,
analysis in this report was limited to the areas where historic and
current flood data was available, particularly the areas surrounding
the City of Bismarck. The analysis can be expanded to include Williams
County in the vicinity of the town of Williston once the updated flood
data becomes available.
3.0 POTENTIAL SILTATION IMPACTS ON FLOOD CONTROL
During the design and construction of a reservoir, siltation rates
are one of the many factors that are considered when determining the
expected life of a reservoir. Excessive siltation rates are those
considered above what is expected when a reservoir is constructed. When
excessive siltation occurs, the storage capacity of a flood control
reservoir is significantly and rapidly decreased. The two most common
impacts associated with excessive siltation are: less water available
for domestic and agricultural use; and decreased flood protection. The
most common causes for excessive siltation are accelerated erosion and
increased runoff associated with change in land use activities
throughout the watershed.
The decrease in storage potential of a reservoir due to siltation
can cause increased downstream flood risks. Increases in probability
and intensity of flood events can result from increased upland erosion,
which causes a decrease in hydraulic capacity of a channel due to
sedimentation. Changes in land use of upland areas may also generate
more runoff in a shorter period and potentially increase flood
intensity. Agricultural and recreational uses may be impacted by the
increased flooding and sediment transport. There may also be an
increase in water treatment costs where water treatment plants draw raw
water from the impacted impoundments, streams and rivers.
There were two FISs prepared by FEMA for Bismarck, North Dakota and
the surrounding area. The 1988 FIS for the city of Bismarck and
Burleigh County Unincorporated areas was compared to the 2005 FIS for
Burleigh County and Unincorporated Areas. The 1988 FIS used an older
version of the Hydrologic Engineering Centers analysis software (HEC-2)
and the 2005 FIS used the HEC River Analysis System software (HEC-RAS).
The models, which were provided by the NDSWC and Houston Engineering,
Inc., were run to simulate the 50-year, 100-year, and 500-year storm
event scenarios. The results of the models were then compared to the
data within the associated report for verification.
The flood profiles from the two models were then compared at key
milestones along the river to determine the change in elevation (Table
3-1). It was found that for the 50-year design storm, flood water
surface elevations had risen by approximately 1.2 feet at the
downstream station and by as much as 1.8 feet within the reach. For the
100-year storm, flood elevations had risen by approximately 1.3 feet at
the downstream station and as much as 1.4 feet within the reach. The
model results also yielded that for the 500-year storm, flood
elevations had risen as much as 1.1 feet at the downstream station.
Although these model simulations provided verification of the water
surface elevation change, they did not provide an explanation for the
increase.
Compilation and review of data from previous studies prepared by
the USACE indicates that sediment is accumulating at various locations
within the main channel of the Missouri River. Table 3-2 shows the
segments of river that have experienced documented sedimentation. The
highlighted segments are located within the reach analyzed in the
Bismarck FIS or downstream from this reach. The sedimentation occurring
in these segments could be impacting the flood elevations in the
Bismarck area. It should be noted that only two of the segments,
identified in bold text in Table 3-2, fall within the reach bounded by
the key milestones identified in Table 3-1.
TABLE 3-1.--FLOOD ELEVATION COMPARISON
--------------------------------------------------------------------------------------------------------------------------------------------------------
Flood Elevations, (feet) NAVD Changes in Flood
------------------------------------------------------ Elevations from 1988 to
Key Milestone River 1988 Flood Data 2005 Flood Data 2005 (feet)
Station --------------------------------------------------------------------------------
50 yr 100 yr 500 yr 50 yr 100 yr 500 yr 50 yr 100 yr 500 yr
--------------------------------------------------------------------------------------------------------------------------------------------------------
Confluence Apple Creek...................................... 1300.21 1626.7 1627.7 1631.0 1627.9 1629.0 1632.1 1.2 1.3 1.1
Confluence Little Heart River............................... 1302.22 1628.3 1629.3 1632.8 1629.6 1630.7 1633.8 1.3 1.4 1.0
Confluence Heart River...................................... 1310.72 1633.7 1634.9 1638.3 1634.5 1635.7 1638.8 0.8 0.9 0.5
Bismarck Expressway......................................... 1313.41 1635.1 1636.3 1639.8 1636.0 1637.3 1640.4 0.9 1.0 0.6
Memorial Bridge............................................. 1314.21 1635.4 1636.5 1640.0 1636.3 1637.5 1640.8 0.9 1.0 0.7
Railroad.................................................... 1314.99 1635.9 1637.0 1640.5 1637.7 1637.9 1641.2 1.8 0.9 0.7
Interstate 94............................................... 1315.49 1636.1 1637.3 1640.7 1636.9 1638.1 1641.5 0.8 0.9 0.8
City of Bismarck Limits..................................... 1317.42 1637.7 1638.9 1642.9 1638.2 1639.6 1643.6 0.5 0.7 0.6
Confluence Burnt Creek...................................... 1319.88 1638.9 1640.0 1643.9 1639.5 1640.8 1644.6 0.6 0.8 0.8
Burleigh County Limits...................................... 1328.64 1644.0 1645.0 1648.5 1643.7 1644.8 1648.4 -0.3 -0.2 -0.1
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source.--Elevations are from HEC-2 data and HEC-RAS data from the 1988 and 2005 Flood Insurance Studies, respectively.
TABLE 3-2.--RIVER SEGMENTS WITH SEDIMENTATION
----------------------------------------------------------------------------------------------------------------
ENDING RIVER MILES WITHIN
STARTING RIVER MILE MILE SEGMENT LEVEL OF SEDIMENTATION
----------------------------------------------------------------------------------------------------------------
1564........................................... 1548 16 Low
1548........................................... 1534 14 Moderate
1534........................................... 1521 13 High
1521........................................... 1489 32 Moderate
1489........................................... 1470 19 Low
1457........................................... 1453 4 Low
1438........................................... 1436 2 Low
1362........................................... 1352 10 Moderate
1303........................................... 1301 2 Low
1301........................................... 1297 4 Moderate
1297........................................... 1290 7 High
1290........................................... 1288 2 Moderate
1288........................................... 1285 3 Low
1285........................................... 1282 3 Moderate
1282........................................... 1270 12 Low
1270........................................... 1248 22 Moderate
1248........................................... 1232 16 Low
----------------------------------------------------------------------------------------------------------------
River miles within the Bismarck FIS boundary with sedimentation.
River miles downstream of the Bismarck FIS boundary with sedimentation.
Source.--Data taken from Berger Aggradations Area Map; October 2008.
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 3-1--Aggradation Based on USACE Studies
4.0 FLOOD CONTROL MEASURES
Siltation in the reach between the Garrison Dam and Lake Oahe has
resulted in increased risk of flooding in the downstream reach between
the dam and the headwater of Lake Oahe. Because of this sediment
aggradation, the impact of ice dams on seasonal flooding is increasing.
As a means to counter this impact, careful sequenced water releases
during the winter months are made to prevent flooding caused by ice
dams.
The Missouri River typically freezes in December, and remains
frozen until the thaw which occurs in March and April. Ice dams can
form during freeze-up as well as during ice break-up. Initial forming
of ice (ice-in) starts at the headwaters of Lake Oahe and moves
upstream towards Garrison Dam. Ice dams formed during break-up are most
common downstream of the confluence between the Missouri River and the
Heart River (river station 1311). According to FEMA (2005), the higher
flows in the Heart River during snowmelt or spring rains cause the
formation of ice dams on the still-frozen Missouri River. With the
siltation causing a higher river bed elevation and resulting higher ice
sheet elevation, flooding impacts are exacerbated as a result.
The USACE releases water at the Garrison Dam in a controlled manner
over the winter months to reduce the ice-in and ice-out risk to
flooding in the Bismarck/Mandan area. The ice break-up which occurs in
March and April can cause ice dams which block the flow of water. This
issue is compounded when spring thaw and rainfall increases the
discharge flow from tributaries into the Missouri River. Proper
management of water releases is able to help control downstream
flooding, but reduced flow during winter months can impact the
production of electrical hydropower.
5.0 CHANNEL GEOMETRY ANALYSIS
As discussed in Section 3.0, Berger compared the output data from
the models associated with the 1988 and 2005 FIS reports and found a
trend for higher water surface elevations and lower minimum channel bed
elevations. Ten river stations, which were selected based on their
proximity to key milestones identified in the aforementioned FIS
reports, were selected for a more detailed analysis. The stations and
their associated water surface and minimum channel elevations are shown
in Table 5-1 and the differences between the values of the two models
are shown in Table 5-2.
TABLE 5-1.--RIVER STATIONS AND ELEVATIONS
------------------------------------------------------------------------
1988 FIS DATA 2005 FIS DATA
-------------------------------------------
Water Minimum Water Minimum
River Station Surface Channel Surface Channel
NAVD 88 NAVD 88 NAVD 88 NAVD 88
(feet) (feet) (feet) (feet)
------------------------------------------------------------------------
1300.21..................... 1627.72 1598.40 1629.04 1603.40
1302.22..................... 1629.31 1601.50 1630.70 1596.10
1310.72..................... 1634.85 1611.30 1635.71 1607.70
1313.41..................... 1636.27 1608.60 1637.27 1606.30
1314.21..................... 1636.53 1602.30 1637.54 1601.50
1314.99..................... 1637.00 1605.00 1637.91 1601.90
1315.49..................... 1637.25 1602.60 1638.12 1598.00
1317.42..................... 1638.90 1610.20 1639.56 1612.60
1319.88..................... 1640.02 1612.90 1640.80 1609.50
1328.64..................... 1645.00 1616.40 1644.82 1617.10
------------------------------------------------------------------------
As demonstrated in Table 5-2, the majority of the river stations
evaluated indicated an increase in water surface elevation. However, a
trend for the minimum channel elevation could not be established.
Because channel geometry and flow characteristics are inherently
related and constantly changing, Berger then compared the cross-
sectional area for each of the 10 river stations to evaluate the
channel geometry to determine if excessive erosion or sedimentation
occurred between the two model years. Changes in the channel geometry
will affect water velocity, assuming a constant discharge, which in
turn influences a river's ability to transport sediment as bed load,
material in contact with the river bed having a diameter larger than
fine sand; or as suspended load, fine materials such as clay and silt
that are held in suspension in the water and carried without contact
with the river bed.
As the velocity of the water in a channel increases, the more
capacity the water has for erosion and transportation of sediment in
the channel. In other words, the sediment transportation power, or the
kinetic energy, of the water is directly proportional to the increased
velocity. When discharge is held constant and width decreases, the
velocity increases and the channel will tend to deepen by eroding the
channel bed, which is referred to as scouring. Kinetic energy is
decreased as water erodes the river channel or moves sediments along
the river bed. In addition, some of the kinetic energy is lost through
turbulence and friction. Once sufficient kinetic energy has been
expended or lost, the deposition of the sediment load will occur.
TABLE 5-2.--COMPARISON OF ELEVATIONS
------------------------------------------------------------------------
Water Surface Minimum
River Station NAVD 88 Channel NAVD
(feet) 88 (feet)
------------------------------------------------------------------------
1300.21................................. 1.32 5.00
1302.22................................. 1.39 -5.40
1310.72................................. 0.86 -3.60
1313.41................................. 1.00 -2.30
1314.21................................. 1.01 -0.80
1314.99................................. 0.91 -3.10
1315.49................................. 0.87 -4.60
1317.42................................. 0.66 2.40
1319.88................................. 0.78 -3.40
1328.64................................. -0.18 0.70
------------------------------------------------------------------------
Studies have demonstrated that for any given discharge, the river
channel bed will adjust to a quasi-equilibrium condition governed by
the kinetic energy transfer between channel flows and the local
resistance associated with the geometry of the river channel, which
directly influences sediment transport. The greater the ratio of the
cross-sectional area of the channel is to the wetted perimeter, the
less the local resistance will be as there is proportionately less
water within the friction zone of the channel (near the sides and bed).
In other words, the channel geometry will stabilize once the water has
reached its maximum sediment load for a given discharge.
One example of particular interest is that water flowing over a
spillway will have very little sediment as most of it will have settled
out upstream of the dam. This water then has a lot of kinetic energy
and is capable of transporting a large amount of sediment. For this
reason, channels immediately downstream of impoundments are
particularly susceptible to the effects associated with erosion.
The gross cross-sectional areas of the 10 river stations were
compared (see Table 5-3) for the HEC-RAS data for both the 1988 and
2005 FIS models. All sections indicate a net increase in cross-
sectional area. These values include both the main channel and the
overbank areas. Detailed analysis of the channel geometry required
evaluation of the main channel cross-section.
The cross-sections of the 10 river stations were plotted with the
output from the HEC-RAS models. The two cross-sections of the main
channel from the 1998 and 2005 FIS models were then visually compared
for each of the river stations. The results of this analysis are
illustrated in Figures 5-1 through 5-10.
TABLE 5-3.--RIVER STATIONS AND GROSS CROSS-SECTIONAL AREA
----------------------------------------------------------------------------------------------------------------
1988 FIS Area 2005 FIS Area Change in Area
River Station (square feet) (square feet) (square feet)
----------------------------------------------------------------------------------------------------------------
1300.21......................................................... 24,685.40 24,936.13 250.73
1302.22......................................................... 25,136.57 27,422.00 2,285.43
1310.72......................................................... 30,438.93 31,333.79 894.86
1313.41......................................................... 21,768.87 28,165.79 6,396.92
1314.21......................................................... 23,065.15 26,082.67 3,017.52
1314.99......................................................... 17,418.97 19,355.91 1,936.94
1315.49......................................................... 14,456.52 15,614.66 1,158.14
1317.42......................................................... 35,911.24 38,000.80 2,089.56
1319.88......................................................... 24,774.47 27,718.37 2,943.90
1328.64......................................................... 19,530.14 20,203.27 673.13
----------------------------------------------------------------------------------------------------------------
Based on the results of the analysis, 7 of the 10 river stations
show a net increase in cross-sectional area within the main channel.
Likewise, 8 of the 10 stations show signs that significant scouring and
sloughing has occurred. Both scour and sloughing are a normal part of a
river's natural erosion processes. Scour of a river channel can occur
due to an increased discharge rate, as mentioned previously, when the
channel geometry is reduced thus increasing the velocity through that
section. These influences can be temporary, such as an increase in
discharge associated with a storm event or a decrease in channel area
caused by debris or ice dams. Sloughing, also commonly referred to as
slumping, is a form of channel bank erosion where the sides of a
channel collapse and are deposited to the bottom of a channel. The main
cause of sloughing is saturation of soil associated with a rise in the
water surface elevation, often followed by a sudden decrease of the
same water elevation. As the water surface falls, it creates a pressure
imbalance within the saturated soil and the resulting forces cause the
soil to erode into the channel bed. The soils that collapse into the
channel bed are often comprised of fine silts and sands and are
therefore more susceptible to scouring. Two of the three areas
identified as having a net decrease in main channel cross-sectional
area are preceded by river stations where sloughing appeared to have
occurred.
There is a significant increase in water surface elevation from the
1988 FIS report and the 2005 FIS report at the downstream river
station. This increase, approximately 1.32 feet, slowly decreases in
subsequent upstream river stations until in the vicinity of river
station 1300.21. However, this does not appear to be attributable to a
channel geometry based on the 10 river sections analyzed. In fact, the
majority of the cross-sections indicated an increase in the area of the
main channel, either through scouring or sloughing, which would lend
itself to a fall in the water surface elevation. The data suggest that
the water surface elevation is either being influenced by a downstream
source or an increased initial water surface elevation used in the 2005
model.
It is important to note that this analysis has a finite study area
and is limited by the accuracy of the data and the HEC-RAS models
provided. It should also be noted that common industry belief is that
this HEC-RAS model, albeit a highly versatile tool, is not able to
accurately model all dynamics of flood events, especially in a highly
urbanized watershed.
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figures 5-1 to 5-4.--River Station Cross-Sections
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figures 5-5 to 5-8.--River Station Cross-Sections
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figures 5-9 to 5-10.--River Station Cross-Sections
6.0 CHANNEL STABILITY ANALYSIS
Channel and bank stability on the Missouri River is a continual
concern as a potential source of sedimentation. Section 33 of the Water
Resources Development Act of 1988 authorized the USACE to alleviate
bank erosion and related problems along the Missouri River from Fort
Peck Dam, Montana to Ponca State Park, Nebraska. The act stated that
both structural and nonstructural measures could be used to address
bank erosion on the river. As a consequence, the stabilization projects
constructed along the river have created concern about the overall
cumulative impacts of bank stabilization on river issues such as fish
and wildlife resources, which resulted in the USACE preparing a report
entitled ``Missouri River--Fort Peck Dam to Ponca State Park
Geomorphological Assessment Related to Bank Stabilization'' (December
2001). The report was prepared as a joint effort by the U.S. Army
Engineer Research and Development Center, University of Nottingham and
Colorado State University (Biedenharn et al). The report studied the
potential geomorphic impacts of the bank stabilization program on
wildlife habit within the Missouri River system with a particular
emphasis on the formation and persistence of habitat bars.
There is a general scarcity of research literature regarding the
effect of further bank stabilization measures on the sediment supply to
the river channel and how this affects the bar and island morphology.
According to Biedenharn et al. (2001), the upper Missouri River
contains numerous bars and islands composed primarily of material from
eroding banks. A report prepared for the USACE by Pokrefke, T.J.,
Abraham, D.A., Hoffman, P.H., Thomas, W.A., Darby, S.E. and Thorne,
C.R. entitled ``Cumulative Erosion Impacts Analysis for the Missouri
River Master Water Control Manual Review and Update Study'' (July
1998), attempted to predict how any future increases in bank
stabilization would affect erosion rates in the four reaches (Fort
Peck, Garrison, Fort Randall and Gavins Point) on the Missouri River.
Of these four, the Garrison Reach is the only reach set solely in the
State of North Dakota. The Pokrefke et al. (1998) report predicted that
an exponential relationship exists between increasing amounts of bank
stabilization and decreasing rates of bank erosion in the three upriver
reaches (Fort Peck, Garrison and Fort Randall), primarily due to the
fact that the upriver reaches are close to a position of dynamic
equilibrium and are stabilizing naturally. By comparison, the Gavins
Point Reach, which is further downriver, has a linear relationship
between increasing bank stabilization and decreasing bank erosion.
The Garrison study reach extends from river station 1390 just
downstream of the Garrison Dam to river station 1311, located just
south of Bismarck where the Heart River connects to the Missouri River.
The reach is regulated by the Garrison Dam. The Biedenharn et al.
(2001) report states that the bed material in the reach is
predominantly sand with occasional outcrops of gravel. The channel in
the Garrison reach is relatively straight, with a moderate to high
degree of braiding with numerous bars and islands. The channel width
ranges from about 430 feet to 4,400 feet, with an average width of
about 2,100 feet. Bank heights within the Garrison Reach generally
range from about 10 feet to 43 feet, with an average bank height of
about 17 feet. The bank material contains approximately 29 percent
fines (silts and clays), with the remainder sands (upper limit
approximately 1 mm in size).
The Biedenharn et al. (2001) report studied the Garrison Reach
using specific gauge sections to study the degradational trend of the
reach. Historically, this reach followed a degradational pattern after
the dam construction was completed in 1953, but this degradational
trend began to subside in the mid 1970s to early 1980s. The report
notes that the gauge records suggest that this reach of the river has
been approaching a state of dynamic equilibrium since the mid 1980s.
This is not to say that the reach has achieved dynamic equilibrium, as
active processes such as widening of the active channel continue to
occur, but it is evident that the rate of change in degradation is
declining.
The Biedenharn et al. (2001) report investigated the relationship
between channel widths and the formations of bars and islands by
comparing the cumulative distribution for two time periods, 1975 and
1997. In general for the Garrison Reach, the channel width in the range
of 2,070 feet appeared to be the threshold zone below which it is
unlikely that bars will exist. Using the collected information for bars
and island formation in the Garrison Reach, the report attempted to
determine a relationship between the percent bank stabilization and the
bar and island density, but found no obvious trends.
A follow-up report, built upon the work presented in the Pokrefke
(1998) and Biedenharn (2001) reports, was prepared under contract to
the USACE by HDR Engineering, IIHR-Hydro science & Engineering,
Mussetter Engineering and WEST Consultants, entitled ``Bank
Stabilization Cumulative Impact Analysis Final Technical Report--Fort
Peck, Garrison, Fort Randall, and Gavins Point Study Reaches'' (March
2008). The HDR report draws on the USACE's 1999 Cumulative
Environmental Impact Statement (CEIS) for on-going bank stabilization
within the Missouri River from Fort Peck Dam to Ponca, Nebraska. The
CEIS was intended to evaluate the cumulative environmental impacts of
past and future banks stabilization construction on the Missouri River.
The HDR report, formed from the draft Appendix C of the CEIS, evaluates
the amount of bank stabilization over two time periods and the
potential relationship between increased bank stabilization and sandbar
habitat formation in the Missouri River within the four study reaches.
The HDR report concluded that there is no correlation between past bank
stabilization construction and evaluated habitat features. As a result,
the USACE declared that there is no geomorphologic basis on which to
alter the rate or amount of bank stabilization currently being
permitted in the Missouri River and postponed the preparation of the
CEIS. Figure 6-1 (HDR, 2008) shows the vicinity map for the Garrison
reach studied in the Biedenharn (2001), Pokrefke (1998) and HDR (2008)
reports.
In studying the Garrison Reach, the HDR (2008) report utilized data
recorded from five stream gauge locations, two sets of aerial
photography taken 17 years apart, channel cross-section survey data,
and HEC-RAS model data. The planform analysis performed in the study
took into account variables such as channel top width, annual flow,
bank material, channel bed material to determine the river trends
within each study reach.
The HDR (2008) report presented a table (Table 1-7, Revetment by
Study Reach) showing the miles of revetment installed for each study
reach and the time periods during which the revetment was installed.
The information was based upon a revetment inventory performed as part
of the HDR study, using a database of bank stabilization constructed by
USACE and authorized by USACE under section 404 of the Clean Water Act,
supplemented by videotape observations of bank stabilization of both
banks of each study reach. The table summarized the percentage of
bankline protected, which is interpreted in the report as the amount of
historic channel high bank stabilized. The historic channel high banks
are stated in the report to be the outer boundaries of a developing,
new flood plain. The report recognizes that the remnant river has a
much smaller main channel which generally migrates within the banks of
the historic channel. The historic or pre-dam river changed
significantly with construction and operation of the mainstem dams. The
revetment identified in the HDR report for the Garrison Reach is shown
in Table 6-1 below.
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 6-1.--Vicinity Map for Garrison Study Reach (HDR, 2008)
TABLE 6-1.--REVETMENT, GARRISON REACH
----------------------------------------------------------------------------------------------------------------
Total Study
Revetment Reach River Bankline
Study Reach (miles) \1\ Year Installed Miles, Both Protected
Banks (percent) \2\
----------------------------------------------------------------------------------------------------------------
Garrison \3\ \4\................................ 24.0 1976-1985 104.2 \2\ 23.0
5.6 1985-1999 104.2 5.4
----------------------------------------------------------------------------------------------------------------
Source: Table 1-7, HDR Report (2008).\1\ The amount of revetment is the amount that exists within the geomorphic reaches, not the total stabilization
that may exist within the total reach as some areas outside the geomorphic study reach have been stabilized.
\2\ The percent of bankline protected reflects the total amount on high bank that is stabilized. Some of this
bankline is no longer adjacent to the active flow channel.
\3\ There were approximately 8 miles of bank stabilization constructed in the Garrison Study Reach prior to
1976, during what is considered the pre-revetment study period.
\4\ The 8 miles of bank stabilization completed prior to 1976 represent about 8 percent of the bankline in the
Garrison Study Reach, which means that 15 percent of the bankline was actually stabilized between 1976 and
1985.
The analysis in the HDR (2008) report measures total flood plain
erosion. Some of this erosion is degradation of the new main channel
(particularly immediately downstream of a dam); some erosion is where
the new channel is widening within its new flood plain, and some
erosion is where the new channel is widening its new flood plain via
erosion of the historic channel bank.
The nature of the Missouri River and its channel planform is that
of a meandering stream, as opposed to a braided stream. The difference
between meandering and braided is shown in Figure 6-2 (HDR, 2008). The
terms are defined in a USACE report by E.W. Lane entitled ``A Study of
the Shape of Channels Formed by Natural Streams Flowing in Erodible
Material M.R.D. Sediment Report Series 9'' (1957) as follows: ``a
braided stream is characterized by having a number of alluvial channels
with bars or islands between meeting and dividing again, and presenting
from the air the intertwining effect of a braid'' and ``a meandering
stream is one whose channel alignment consists principally of
pronounced bends, the shapes of which have not been determined
predominantly by the varying nature of the terrain through which the
channel passes.'' It is important to note that the Lane report
indicated that, prior to construction of the five lower mainstem dams,
the Missouri River exhibited characteristics closer to a meandering
stream. This conclusion was based upon plotting a number of U.S. rivers
to determine the relationship between slope and mean discharge and a
stream's tendency to exhibit a braided or meandering planform. The HDR
(2008) report points out the popular misconception held by many that
the pre-dam construction Missouri River was a braided river due to the
numerous sandbars and shallow water habitat.
Thus, the Missouri River which flows today is classified as a
meandering steam, but has changed from its original meandering stream
nature before the dam construction. The Missouri River floodplains of
today are primarily confined to the historic channel, which is several
thousand feet wide compared to the several-mile-wide historic
floodplain. The HDR report presents a floodplain analysis which
demonstrates that flows in excess of the 500-year discharge flow are
needed to produce overbank flooding of the historic floodplain in the
study reaches where degradation has occurred. The dams have, in effect,
completely eliminated vast flooding of the historic flood plain. Post-
dam construction degradation has effectively eliminated inundation of
this new flood plain in the Garrison Reach, except during very high
flow periods, such as those experienced in the late 1990s.
Analysis of the placement of bank stabilization on the Missouri
River was assumed to be only where the river, as defined by the main
channel, would come in contact with the outside edge of the new,
developing flood plain boundary (historic channel bank). As such, the
main channel is free to meander within the new flood plain which is the
new natural process related to post-dam construction conditions. Figure
6-3 (HDR, 2008) shows an aerial view of the Missouri River floodplain
along the Garrison Reach at river station 1351.7. The new floodplain is
shown within the historic channel with the historic floodplain
displayed outside of the new floodplain.
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 6-2.--Types of Channel Planform (HDR, 2008)
A cross-section view of the Missouri River along the Garrison Reach
at river station 1362.7 is shown in Figure 6-4 (HDR, 2008). The
vertical scale depicts the elevation of the channel and the new high
banks and compares the cross-section from two study periods, 1976 and
1999. It demonstrates the changes which take place between 1976 and
1999, showing the main channel migrating from one side of the flood
plain to the other. Degradation with the bank station is also seen in
Figure 6-4, as well as limited erosion on the channel banks. Figures 6-
3 and 6-4 support the concept that stabilizing the high bank of the old
channel still allows the river to migrate within the high banks of the
old channel. This allows the sandbars, islands and attached habitat
within the historic high banks to erode, with eroded material then
deposited downstream. The HDR report states that although analysis is
unable to measure how this stabilization might affect the trend toward
dynamic equilibrium, the local effect of this stabilization is
eliminated when the main channel migrates away from the stabilization
location.
Erosion of the bank and bed was analyzed for the Garrison Reach by
Biedenharn et al. (2001). The erosion rate was estimated by summing the
left and right bank erosion rates for each geomorphic reach length.
Bank erosion rates were estimated based upon measurement of the area of
bankline eroded as evidenced by aerial photographs or through analysis
of channel cross-section surveys. From analysis of the erosion rates
presented in Biedenharn (2001), the report published in Environmental
Conservation in 2000 by F.D. Shields, A. Simon and L.J. Steffen
entitled ``Reservoir Effects on Downstream River Channel Migration,''
concluded that the mean erosion rate in the Garrison Reach has
decreased more than fourfold since the closure of Garrison Dam. The
Shields et al. (2000) report also stated that much of the reach has
experienced net channel widening and deposition rates of alluvial
material to form islands and bars have decreased from 408 to 3.2 acres/
year. The effect of the Garrison Dam has been to a reduction in
magnitude of the Missouri River high flows in this reach as well as a
change in timing (from April to July pre-dam to February to March post-
dam). The resulting control by the dam in reducing higher flows has
acted to reduce overbank flows. The HDR (2008) report concluded that
channel changes must occur as a result of processes acting only on the
banks, including a loss of sedimentation by mass wasting due to a lack
of prolonged periods of high-stage saturated banks.
The HDR (2008) report assessed the impact of increased bank
stabilization within the Garrison Reach. The upstream and downstream
controls (mainstem dams) provide upstream clear-water release and a
downstream backwater. This results in scouring and lowering of the
degradation zone portion of the channel in the upstream reaches and an
aggradational effect in the lower portion of the reach. The elevation
of the channel bed is raised in the aggradation zone and the channel
begins to display braided characteristics within a meandering regime as
it becomes wider and shallower, a result of the backwater condition and
delta formation at the headwater of Lake Oahe.
The banks along the Garrison Reach generally are composed of fine
sands, while the channel bed is composed of coarser sands and cobbles.
The channel bed has changed since the construction of the mainstem
dams, as the channel bed material in the degradation zone has become
coarser. This increase is a result of sediment-free releases from the
Garrison Dam removing the fines and leaving the coarser material to
remain, in order to maintain the river's sediment load. Further
downstream, this condition becomes less prevalent as the river carries
more sediment. Upon reaching the depositional zone, the channel beds
are comprised of increasingly finer material.
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 6-3.--Missouri River Floodplain, Garrison Study Reach (HDR,
2008)
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 6-4.--Cross-Section at River Station 1362.7, Garrison Study
Reach (HDR, 2008)
The bank stabilization features along the Garrison Reach were
constructed to prevent bank failure and as a result, serve to limit the
bank materials from entering the river. The HDR (2008) report states
that, in general, placing rock or other stabilization features may not
totally prevent movement of bank materials. The effectiveness of the
bank stabilization features depends on the structure's construction. It
is possible that fines may be ``piped'' through the stabilization
structure or that rock may be undersized and move as result from river
flow impacting it. Also, stabilization features may be outflanked or
undercut by the river flow. Rock that may have been initially sized
properly during installation may become undersized due to freeze-thaw
action and aging. However, HDR (2008) does acknowledge that, in
general, most bank stabilization structures tend to prevent most bank
erosion and can be considered effective for their intended purpose.
The HDR (2008) report concludes that bank and channels may
experience erosion immediately downstream of bank stabilization
structures through several mechanisms. Bank stabilization structures
immediately downstream of the dam may prevent the erosive, sediment-
free dam discharge from removing bank material in this location,
resulting in an increased channel erosion pressure and relocating the
bank erosion zone further downstream. Generally, this is most
pronounced in the first geomorphic reach below the dam.
Bank stabilization structures prevent the widening of the channel.
This prevents the reduction in stream power and relief of shear stress
on the channel bed from taking place if the channel were allowed to
widen. However, because bank stabilization has been constructed only
where the new main channel of the river is in contact with historic
high banks of the river, the new channel is free to migrate away from
the stabilized bank.
A hardened outer bank may induce secondary currents, potentially
causing erosion or scouring along the toe of the outer bank and
increasing erosion at the end, or flank, of the hardened bank. Further,
a hardened bank may also induce erosion immediately downstream as a
result of changes in either the roughness or the current direction.
The HDR (2008) report summarizes that the channel will tend to
stabilize over time in the erosion-related mechanisms discussed above.
The Garrison Reach contains approximately 29 percent bank stabilization
coverage and the bank erosion rate within this reach is in a decreasing
trend.
7.0 ADDITIONAL ANALYSIS
The FEMA floodplain mapping and HEC-RAS model output were analyzed
to compare limits of current versus historic flood inundation for the
100-year storm event. This comparison was conducted for the river's
extent within Burleigh County as well as within just the Bismarck city
limits. Table 7-1 compares the areas of the 100-year flood inundation
between the 1985 FIS to the 2005 FIS.
TABLE 7-1.--FLOODPLAIN AREA COMPARISON
------------------------------------------------------------------------
Burleigh County Bismarck City Limits
------------------------------------------------------------------------
1985 100-year Floodplain--28 1985 100-year Floodplain--2.7 mi\2\
mi\2\
2005 100-year Floodplain--36 2005 100-year Floodplain--3.6 mi\2\
mi\2\
------------------------------------------------------------------------
mi\2\ = square miles
The area of the 100-year floodplain has increased by nearly 28.6
percent within Burleigh County from the 1985 FIS to the 2005 FIS. The
floodplain area within the Bismarck city limits has increased by
approximately 18.5 percent and accounts for approximately 6.3 percent
of the net increase within the county. This is of particular concern to
property owners whose property now lies within the floodplain. Two of
the potential impacts for property owners associated with this are
devaluation of the property and the requirement to purchase flood
insurance. Homes, businesses, and agricultural land are among the types
of properties most heavily affected by the floodplain area increase.
As discussed in the previous sections, increased water surface
elevations and increased floodplain area could be the result of areas
with high aggradation and/or the natural morphology of the river
changing and/or restricting the channel's ability to convey the flow
associated with a particular storm event.
8.0 SUMMARY AND RECOMMENDATIONS
This report assesses the potential impacts of siltation in the
Missouri River Basin within the State of North Dakota on flood control.
The report incorporates the review of relevant existing data and
information from prior studies and research programs. As defined by the
U.S. Army Corps of Engineers (USACE), the study area includes the
watershed of the mainstem of the Missouri River border from the North
Dakota/South Dakota border on the downsteam end and the Montana/North
Dakota border on the upstream end. Included with this study area are
the Garrison and Oahe dams and the reservoirs associated with each dam,
Lake Sakakawea and Lake Oahe, respectively.
The Garrison and Oahe Reservoirs have defined zones for flood
control, multiple uses, and permanent pool. These zones are utilized to
control flow on the Missouri River and meet multiple and potentially
conflicting goals.
Flood control issues within the Missouri River for the Bismarck,
North Dakota area are caused or affected by: (1) open-water season
flooding from Garrison Dam operations; (2) open-water season flooding
from tributaries, and other residual drainage areas below Garrison Dam,
combined with releases from Garrison Dam; (3) flooding, resulting from
ice jams and ice conditions; and (4) flooding caused by aggradation in
the upper reaches of Lake Oahe.
This report reviews Flood Insurance Studies (FIS) prepared by the
Federal Emergency Management Agency (FEMA) for the Bismarck, North
Dakota area to analyze changes in water surface elevation and its
affects on flooding.
Siltation in the reach between the Garrison Dam and Lake Oahe has
resulted in increased risk of flooding in the downstream reach between
the dam and the headwater of Lake Oahe. Because of this sediment
aggradation, the impact of ice dams on seasonal flooding is increased.
As a means to counter this impact, careful sequenced water releases
during the winter months are made to prevent flooding caused by ice
dams. Water release from the Garrison Dam is also used to provide flood
control during other seasons as well.
Evaluation of the data from the 1998 and 2005 FIS reports indicates
that the water surface elevation has increased. Analysis of the channel
geometry was conducted at ten river stations, which revealed that the
net cross-sectional area of the river channel has increased at most of
the river sections from the 1998 model to the 2005 model. This is
likely the result of erosion in the form of scour and sloughing.
The changes in channel geometry are likely not the cause of the
increase in the water surface elevation. The data suggest that the
water surface elevation is either being influenced by a downstream
source or an increased initial water surface elevation used in the 2005
model.
Channel and bank stability on the Missouri River is a concern as a
potential source of sedimentation. Stabilization projects, including
structural and non-structural measures, constructed along the river for
the purposes of alleviating bank erosion (authorized by section 33 of
the Water Resources Development Act of 1988), have created concern
about the overall cumulative impacts of bank stabilization on river
issues, such as fish and wildlife, recreation usage, and flood zone
control.
Within the Garrison Reach, the upstream and downstream controls
(mainstem dams) provide upstream clear-water release and a downstream
backwater. This results in scouring and lowering of the degradation
zone portion of the channel in the upstream reaches and an
aggradational effect in the lower portion of the reach. The elevation
of the channel bed is raised in the aggradation zone and the channel
begins to display braided characteristics within a meandering regime as
it becomes wider and shallower, a result of the backwater condition and
delta formation at the headwater of Lake Oahe.
The impact of increased bank stabilization within the Garrison
Reach appears to result in a decreasing rate of bank erosion within the
reach. The Garrison Reach contains approximately 29 percent bank
stabilization coverage.
Table 8-1 summarizes the impacts evaluated in this report and
provides recommendations on how to address these impacts related to
sedimentation.
TABLE 8-1.--IMPACT SUMMARY AND RECOMMENDATIONS
----------------------------------------------------------------------------------------------------------------
Impact Significance Timeline Recommendation
----------------------------------------------------------------------------------------------------------------
Reduced storage capacity in Oahe Significant......... Near term (1 to 5 Continue to study potential
and Garrison Reservoirs. years). methods to reduce aggradation
upstream of reservoirs
Aggradation of sediment within Significant......... Near term.......... Study impacts of dredging and
main channel. identify specific sections of
channel downstream of Bismark
which could benefit from limited
dredging program
Aggradation of sediment raises Significant in some Near term.......... Continue sequenced water release
impact of ice dams on seasonal areas. during winter months and identify
flooding. when ineffective to make
necessary corrections
Cumulative effects of Minor Significance.. Long term.......... Continue to study cumulative
stabilization projects on river effects of bank stabilization on
issues. fish and wildlife, new or on-
going stabilization projects to
include eco-friendly design
techniques
Channel stability/geometry....... Possibly Significant Near term.......... Additional study needed to
determine reaches most impacted
from sloughing and slumping
Channel stability................ Possibly Significant Near term.......... Identify reaches where eco-
friendly bank stabilization
techniques can be applied and
will achieve reduction of
aggradation downstream
----------------------------------------------------------------------------------------------------------------
9.0 REFERENCES
Biedenharn, D.S., R.S. Soileau, L.C. Hubbard, P.H. Hoffman, C.R.
Throne, C.C. Bromley, and C.C. Watson, December 2001. Missouri River--
Fort Peck Dam to Ponca State Park Geomorphological Assessment Related
to Bank Stabilization. U.S. Army Corps of Engineers Omaha District.
Dey, S.K., July 2008. River Bank Erosion. Working paper. Khulna
University. http://www.scribd.com/doc/4395500/River-Bank-Erosion.
FEMA. September 1985. Flood Insurance Study--City of Bismarck,
North Dakota Burleigh County. Community Number 380149. Federal
Emergency Management Agency.
FEMA. September 1985. Flood Insurance Study--Burleigh County, North
Dakota Unincorporated Areas. Community Number 380017. Federal Emergency
Management Agency.
FEMA. July 2005. Flood Insurance Study--Burleigh County, North
Dakota and Incorporated Areas. FIS Number 38015CV000A. Federal
Emergency Management Agency.
HDR Engineering, IIHR-Hydroscience & Engineering, Mussetter
Engineering and WEST Consultants, March 2008. Bank Stabilization
Cumulative Impact Analysis Final Technical Report--Fort Peck, Garrison,
Fort Randall, and Gavins Point Study Reaches. U.S. Army Corps of
Engineers Omaha District.
Lane, E.W., 1957. A Study of the Shape of Channels Formed by
Natural Streams Flowing in Erodible Material, M.R.D. Sediment Series
Report 9.
Muller, R,, April 2000. The Importance of Regulating the discharge
of the Reservoir at the End of a Heavy Rainfall Period. Two Lakes
Dreams Realized. http://www.twolakesms.com/April_Slough.htm.
Pokrefke, T.J., D.A. Abraham, P.H. Hoffman, W.A. Thomas, S.E.
Darby, and C.R. Thorne, July 1998. Cumulative Erosion Impacts Analysis
for the Missouri River Master Water Control Manual Review and Update
Study. U.S. Army Corps of Engineers Omaha District.
Remus, J., 2008, Sedimentation in the Upper Missouri River Basin.
U.S. Army Corps of Engineers. http://watercenter.unl.edu/
MoRiverMainstem/Sedimentation.asp Accessed November 20, 2008.
Shields, F.D., A. Simon and L.J. Steffen, 2000. Reservoir Effects
on Downstream River Channel Migration. Environmental Conservation
27(1): 54-66.
USACE. 1993. Aggradation, Degradation, and Water Quality
Conditions: Missouri River Mainstem Reservoir System. U.S. Army Corps
of Engineers Omaha District.
USACE. 2001 Missouri River--Fort Peck Dam to Ponca State Park
Geomorphological Assessment Related to Bank Stabilization. U.S. Army
Corps of Engineers Omaha District.
USACE, Coastal and Hydraulics Laboratory. Bank Sloughing. http://
chl.erdc.usace.army.mil/erosion.
Contacts
Jeff Klein, State NFIP Coordinator North Dakota State Water
Commission [email protected] 701-328-4898
Bruce Englehardt, Investigations Section Chief North Dakota State
Water Commission [email protected] 701-328-4958
Nancy Steinberger, Regional Engineer FEMA in Denver
[email protected] 303-235-4992
Gregg Thielman, P.E. Houston Engineering Inc.
[email protected] 701-237-5065
appendix g--impacts of siltation of the missouri river on indian and
non-indian historical and cultural sites in north dakota
1.0 INTRODUCTION
Berger was tasked by the U.S. Army Corps of Engineers (USACE) to
assess the potential impacts of sedimentation in the Missouri River
within the State of North Dakota. This assessment is intended to meet
the level of effort defined in the Missouri River Protection and
Improvement Act. The assessment was to be based on review of relevant
existing data and information. The study area was defined by the USACE
to include the watershed of the mainstem of the Missouri River from the
North Dakota/South Dakota border on the downstream end to the Montana/
North Dakota border on the upstream end (Figure 1-1). This report
analyzes the potential impacts of sedimentation on Indian and non-
Indian historical and cultural sites.
This appendix is a brief report that describes the potential
impacts to Indian and non-Indian cultural resource sites. It provides a
summary of the types and locations of the records that were consulted
and a description of the qualifying properties within the project area.
The project area is considered the areas of potential aggradation or
siltation (Figure 1-2 through Figure 1-5). The area possessing the
potential for Indian and non-Indian sites is known as the area of
potential effects (APE). For this assessment, the APE is considered to
be the area between the historic low water mark in 2007 and the
ordinary high water mark at Lake Sakakawea (1,850.0 feet above mean sea
level--msl) (USACE 2006a) and Lake Oahe (1,620 feet msl) (USACE
2004a).\1\ However, the research conducted by USACE includes all sites
within the footprint of Lake Oahe and Lake Sakakawea, and are not
separated into the portion of the shoreline between the low and high
water marks.
---------------------------------------------------------------------------
\1\ To protect the cultural resources, location information is not
included.
---------------------------------------------------------------------------
The report identifies the impacts to cultural resources that should
be monitored and/or mitigated as a result of siltation along waterways
and reservoir margins to comply with various statutes, regulations, and
USACE policies. Such impacts include deposition of sediments on extant
Indian and non-Indian historical and cultural sites. In some cases, a
layer of sediment covering a cultural site is beneficial because it
protects the site from weathering, erosion, and intentional or
unintentional human actions. For standing structures, the impact may be
considered adverse because moisture and sediments can destroy
foundations and walls. Along reservoir margins, siltation followed by
fluctuation in water levels tends to cause more damage to sites because
of newly created cut banks and erosion. The integrity of sites is
damaged and much cultural and scientific data are lost.
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 1-1.--Location of Study Area
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 1-2.--Aggradation Area Map 1
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 1-3.--Aggradation Area Map 2
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 1-4.--Aggradation Area Map 3
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Figure 1-5.--Aggradation Area Map 4
2.0 METHODOLOGY
2.1 Literature and Data Search
To identify data on cultural resources, Berger performed a review
of the records on file at the following agencies and repositories, as
available:
--USACE records repository (provided by USACE personnel)
--North Dakota State Historic Preservation Office (NDSHPO)
--Appropriate Tribal Historic Preservation Officers (THPO)
Berger entered information on all properties located within the APE
into a database, including all properties listed in the National
Register of Historic Places (National Register); properties determined
eligible for listing by the Keeper of the National Register; properties
in the process of being nominated to the National Register; properties
determined eligible by consensus determination by the SHPO; and
properties identified in the SHPO inventory as meeting the National
Register criteria.
2.2 Analysis
The potential impacts on and relationships to Indian and non-Indian
historical and cultural sites were analyzed in terms of duration
(short-term versus long-term) and magnitude of effects to significant
resources. Significant resources are those determined to meet specific
evaluation criteria contained in 36 Code of Federal Regulations (CFR)
60.4--Criteria for Evaluation: (a) that are associated with events that
have made a significant contribution to the broad patterns of our
history; or (b) that are associated with the lives of persons
significant in our past; or (c) that embody the distinctive
characteristics of a type, period, or method of construction, or that
represent the work of a master, or that possess high artistic values,
or that represent a significant and distinguishable entity whose
components may lack individual distinction; or (d) that have yielded,
or may be likely to yield, information important in prehistory or
history.
Sites that meet at least one of the criteria are considered
eligible for inclusion in the National Register and are afforded a
level of protection by Federal and State agencies.
The report also contains recommendations for solutions to siltation
with respect to cultural resource sites.
3.0 BACKGROUND AND CULTURE HISTORY
3.1 Prehistoric Period
The prehistory of the Great Plains is divided into five general
time periods consisting of: the Paleo-Indian, Plains Archaic, Plains
Woodland, Plains Village, and the Historic (NDSHPO 2003; USACE 2004b;
USACE 2006b). The project area may either contain the physical remains
of prehistoric properties or the potential to harbor such properties.
The physical remains of past human occupation occurring within the
project area are identified as sites. The contents of a site and its
component parts are described as artifacts or features. An artifact is
defined as an object than can be carried off such as a projectile point
or pottery sherd and a feature is defined as an object that is non-
removable without mechanical means, such as a structure or rock art
panel. The manner in which ancient people manufactured tools,
constructed shelters, or domesticated wild plants is an important
aspect of understanding a cultural group's development through time.
The Missouri River watershed within central North Dakota contains a
diverse and in-depth cultural history. Numerous American Indian tribes
containing extensive oral traditions have identified properties within,
and in close proximity to, the project area. These properties consist
of places where events significant to the development of their culture
have occurred and are referred to as traditional cultural properties
(TCPs). Through the examination of these oral traditions, in
conjunction with linguistic and archaeological studies, we can gain a
better insight to which native cultural group(s) may potentially be
affiliated with the prehistoric properties within the project area.
The Division of Historic Preservation of the State Historical
Society of North Dakota published Historic Preservation in North
Dakota, II: A Statewide Comprehensive Plan, which divides the State
into 13 study units for archaeological research. The Missouri River and
associated reservoirs fall primarily within the Garrison, Souris River,
and Bismarck Study Units. The Division separates the cultural
prehistory of North Dakota into five distinct themes based on a
cultural chronology spanning approximately 11,500 years (NDSHPO 2003).
The Cultural Resource Management Plans (CRMPs) for Lake Sakakawea and
Lake Oahe developed by USACE also define five prehistoric periods that
differ slightly from the Division of Historic Preservation (USACE
2004b; USACE 2006b). The categories of both the NDSHPO and USACE are
shown in Table 3-1.
TABLE 3-1.--PREHISTORIC CHRONOLOGIES OF NORTH DAKOTA
------------------------------------------------------------------------
Cultural Period NDSHPO Chronology USACE Chronology
------------------------------------------------------------------------
Pre-Clovis...................... N/A............... Prior to 13,000
B.C.
Paleo-Indian.................... 9,500-5,500 B.C... 13,000-9,500 B.C.
Plains Archaic.................. 5,500-400 B.C..... 9,500 B.C.-A.D. 1
Plains Woodland................. 400 B.C.-A.D. 1850 500 B.C.-A.D. 1000
Plains Village.................. A.D. 1000-1850.... A.D. 900-1750
Equestrian Nomadic.............. Mid A.D. 1700-1851 N/A
------------------------------------------------------------------------
The following sections contain excerpts from the USACE CRMPs for
Lake Oahe and Lake Sakakawea and is provided with the approval of
USACE. These CRMPs are not accessible to the public in compliance with
a Programmatic Agreement (PA) among the USACE and participating tribes
to protect site location information. Therefore, the indented text in
each section is provided as information to the reader that would not
otherwise be available.
Pre-Clovis
Although no evidence exists for pre-Clovis occupation within the
project area, the potential exists for the area to harbor deeply buried
subsurface intact pre-Clovis evidence. The most convincing pre-Clovis
evidence in North America may come from the Meadowcroft rock-shelter
site in Pennsylvania (Adovasio et al. 1977, 1978, 1980). Additional
possible associated sites containing a pre-Clovis horizon are Pendejo
Cave, New Mexico (Chrisman et al. 1996:357-376), Selby/Dutton and Lamb
Springs, Colorado (Stanford 1979; Stanford et al. 1981), and the Big
Eddy Site, Missouri (Ray 1997). While none of these sites are
unequivocal, their existence lends credence to some oral tradition
stories describing a gradual development in tool making as people
adapted to their changing environment (USACE 2004b).
Paleo-Indian
The Paleo-Indian tradition is characterized by hunting and
gathering adaptation, primarily of now extinct big game animals.
Diagnostic artifacts or sites in North Dakota are typically attributed
to the Clovis, Goshen, Folsom, Hell Gap-Agate Basin, Cody, Parallel
Oblique Flaked, Pryor Stemmed, and Caribou Lake projectile points
manufactured by the Paleo-Indian complexes.
Sites identified as Clovis are generally kill sites and processing
stations containing fossilized mega-fauna remains, but there have been
a few campsites, quarry sites and base sites associated with Paleo-
Indian occupation (Fiedel: 1987). Other Paleo-Indian sites in the West
include the Anzick site, Montana (Lahren & Bonnichsen: 1974), and the
Drake site, Colorado (Stanford: 1991). Evidence from Anzick suggests
tool caches may be related to the burial practices of Clovis people.
Clovis is the earliest recognizable culture complex--a complex which
occurs repeatedly, in patterned and predictable contexts, in the Great
Plains (Wood: 1980).
Plains Archaic
The Plains Archaic complexes recognized in North Dakota include
Oxbow, McKean Lanceolate, Duncan, Hanna, Pelican Lake, and Yonkee as
determined by the projectile point style. This tradition subsumes
hunting and gathering adaptation to essentially modern flora and fauna.
The atlatl was developed during this period and became the new hunting
instrument of choice. The Plains Archaic people maintained a nomadic
hunter/gatherer lifestyle and continued to hunt the larger mammals of
the plains to include bison, elk, deer, and antelope.
Early Archaic.--The Early Plains Archaic period is most commonly
associated with the Folsom Complex whose significant diagnostic
artifact is the Folsom deep fluted projectile point. In Lakota this
point is identified as hist'ola blaha, ``tapered without barbs''
(Mesteth & Charging Eagle: 2000). Their tool technology was advanced
and the archaeological evidence of early Folsom people consists of
artifacts such as channel flakes, end scrapers, side scrapers, bifacial
knives, burins, gravers, drill tools, choppers, ground stone abraders,
bone awls, eye needles, tubular bone beads, and bone disks (Gunnerson:
1987). Folsom sites in this region are the Moe (Schneider: 1975), Lake
Ilo and Winter sites (Haug: 1982) in North Dakota, and the Agate Basin
(Frison & Stanford: 1982), Hell Gap (Irwin-Williams et al. 1973) and
Carter Kerr/McGee Sites (Frison: 1984) in Wyoming.
Middle Archaic.--The Middle Archaic people continue to live as
nomadic hunter/gatherers, but climate conditions were changing and the
last remaining megafauna in North America he'halogeca iyececa,
``longhorn buffalo--Bison Antiquus'' becomes extinct. This extinction
forced people to alter their subsistence patterns and dependence upon
smaller mammals, birds, fish, shellfish, and plants brought about a
change in their tool making technology and their cultural development.
Foraging for food plants takes on a greater importance during this
period and archaeologists have become aware that foraging could be the
basis for developing quite complex societies (Fiedel: 1987).
As groups settled into more localized hunting territories an
increased reliance upon local lithic resources occurred. The long thin
lanceolate point tradition began to disappear and replacing them were
side-notched projectile point types such as Hawken, Logan Creek, Oxbow,
Bitterroot, Pahaska Side-notched, and Blackwater Side-notched points
(Frison et al. 1996; Gregg et al. 1996). The use of local lithic
material and more sparse use of exotic material in archaeological
assemblages dated to this period seem to support this conclusion (Gregg
et al. 1996; Fiedel: 1987). Modern bison remained the principle game
for native people living across the Plains and this is demonstrated in
the Hawken site in Wyoming (Frison et al. 1976), the Head-Smashed-In
site (Reeves: 1978) in Alberta, Canada, the Smilden-Rostberg site
(Larson & Penny: 1991) in North Dakota and the Granite Falls site
(Dobbs & Christianson: 1991) in Minnesota. A number of habitation sites
for this period have been discovered in the Big Horn Mountains of
Wyoming, the Black Hills of South Dakota, and the Pryor Mountains of
Montana. There are two important complexes identified in the Northern
Plains for this period, Oxbow and McKean (Dahlberg and Whitehurst
1990:80; Frison et al. 1996).
Terminal Archaic.--Terminal Archaic people are much more diverse
culturally and linguistically. On the northern plains the Pelican Lake
Complex manifests itself and spreads across Alberta, Saskatchewan,
Manitoba, Montana, North and South Dakota, Idaho, Wyoming, Northern
Colorado and Nebraska (Peterson et al. 1996). The diagnostic artifact
is a thin, corner notched projectile point with wide, deep-notched
corners or barbs on it (Frison: 1991). Sites attributed to Pelican Lake
are the Head-Smashed-In (Reeves: 1978) site in Alberta Canada, and the
Kobold (Davis & Stallcop: 1965) and Keaster (Frison: 1991) sites in
Wyoming. Tool kits include scrapers, chisels, bifaces, choppers, drills
and a variety of multi-purpose flake tools. The bone tool assemblage
for Pelican Lake people consists of awls, beamers, hide-grainers,
scrapers and antler tine flakers (Greg, et al. 1996).
Known Archaic property types include animal kill sites, camps,
Knife River flint quarry sites, lithic workshops, and burial sites
(NDSHPO 2003).
Plains Woodland
The Plains Woodland culture continued the hunting and gathering
adaptations, but can be characterized by increased sedentism, expansion
of regional trade networks the practice of elaborate mound burials,
production of ceramic vessels, and the intensified use of horticultural
through indigenous seedy plants and grasses for supplemental food
(Griffin 1967). During this period the bow and arrow replaced the
atlatl at approximately A.D. 600.
Early Plains Woodland.--The Early Plains Woodland period is
generally associated with the development of ceramic technology
(pottery), generally stone-tempered with cordmarked exteriors (Montet-
White: 1968; Adair: 1996). The bow and arrow was introduced (Adair:
1996) replacing the throwing darts used by Archaic people. This period
on the Dakotas is poorly understood and the Naze site (Gregg: 1987) was
one of first to be excavated. The information from Naze and other sites
in the region basically identifies Early Plains Woodland sites as
seasonal use sites (Benn 1990). Applicable traditions for this period
describe the establishment of a distinct Dakota language cultural group
inhabiting portions of the Ohio River valley. These Dakota speakers are
the direct descendants of the Indian Knoll cultural group (Terrell:
1974).
Middle Plains Woodland.--The Middle Plains Woodland is best
characterized by the widespread manufacture of pottery, constructing
permanent village sites, and the establishment of well-organized trade
relations between different cultural groups specifically centered on
the Hopewell culture. In the Midwest material resources and ornate
objects were widely distributed as a result of these trading
relationships and in Hopewell sites archaeologists have discovered
obsidian from the Black Hills and Rockies, copper from the Great Lakes,
shells from the Atlantic and Gulf coasts, mica from the Appalachians,
silver from Canada, and alligator skulls from Florida (Waldman: 1985).
Middle Plains Woodland people did have contact with Hopewellian people.
Knife River flint artifacts have been found in a few Early and Middle
Plains Woodland sites in Iowa (Benn: 1983). The location of Middle
Woodland sites suggests the gradual adaptation to more sedentary
lifestyles. Settlement patterns among these people involved permanent
to semi-permanent base camps typically situated at the base of bluffs
or on side streams within the bluffs of large valleys (Fortier: 1984;
Roper: 1979).
Late Plains Woodland.--Late Plains Woodland is a time when mound
building cultures faded out and people living in the Midwest began
reverting to more nomadic, possibly less rigorously structured
societies as major population centers were abandoned and people
dispersed and spread out. There are important cultural changes taking
place during this period that set the stage for the development of the
Plains Village stage (Ford: 1977). Some noticeable changes are
modification of ceramic technology and the development of an
agricultural economy. An increase in the importance of maze is noted
throughout the Midwest during this period (Ford: 1977; Kelly 1984).
Settlements were widely spread across the landscape and this was
probably due to population growth. Habitation sites became more and
more common above floodplain terraces along the Missouri River and its
tributaries (Ludwickson et al. 1987).
The North Dakota Plains Woodland complexes include Sonota/Besant,
Laurel, Avonlea, Blackduck, Mortlach, Old Women's, and Sandy Lake
sites. Typical Plains Woodland property types include burial mounds and
other burial sites, occupations, camps, quarries and lithic procurement
areas, and bison kill sites (NDSHPO 2003).
Plains Village
The Plains Village tradition consisted of horticulturalists, as
well as hunters and gatherers. The Plains villages dominated the North
Dakota cultural scene from as early as A.D. 1000 until 1780 and
included contact with European trappers and early settlers. Much of the
later Plains Villages were decimated by the contraction of European
diseases. One of the key elements in Plains Village adaptive strategies
was the development of a dependable, storable surplus food supply
primarily in the form of dried corn. Stored food facilities are
indicative of the Plains Village period.
The Plains Indian Village period is a time when the people
inhabiting the Missouri River basin began establishing permanent
village sites along the Missouri River and its tributaries. Plains
village dwellers learned to plant the seeds traded to them from the
Indians of the mound and temple building cultures in small garden plots
they cultivated next to their villages. As people settle down and move
farther and farther away from the nomadic lifestyles of their
ancestors, they learned how to build earth lodges surrounded by
protective wooden palisades or ditches. Gradually as villages grow
larger in size small garden plots become tilled fields. Annual crops of
corn, beans, squash, and sunflowers were raised and stored as winter
food surpluses. Manufacturing pottery became wide spread among the
tribes as they developed regional trading centers located throughout
the plains. The Plains Village period may be divided into two variants,
but both periods overlap each other and share cultural traits. The
variants are the Middle Missouri Tradition (A.D. 900--A.D. 1200) and
the Coalescent Tradition (A.D. 1200--A.D. 1740) (USACE 2006b).
Middle Missouri Tradition.--Middle Missouri Tradition represents
the first sedentary village occupations of the Missouri River and its
tributaries occurring where agriculture becomes more important than
bison hunting (Winham & Calabrese: 1998:278). When corn was introduced
tending to the crops during growing season forced people to remain in
place for part of the year. This brought about a much more sedentary
lifestyle that also required people to carefully choose a good location
for establishing a village site where an ample supply of water, wild
game, and wild plants could be easily obtained to sustain them until
the crops were ready for harvesting (Zimmerman: 1985). Growing an
abundance of crops allowed population levels to increase. Subsequently,
when bands divided among themselves to occupy and settle new areas they
could take their main food source with them. This meant that pottery
became more important because it was used to store and cook the plants
people are growing (Zimmerman: 1985).
At the end of the period a variant complex within Middle Missouri
called the Extended Middle Missouri Variant (EMM) began to appear.
Sites attributed to the EMM are located along the Missouri River in the
area of the Bad and Cheyenne Rivers, and are labeled as the Bad River
phase (Winham & Calabrese: 1998). The Bad River phase is linked to the
historic Arikara occupation of the area. Another variant complex, the
Terminal Middle Missouri Variant (TMM), is believed directly related to
EMM. The people of the TMM variant are considered ancestral to the
Mandan (Johnson: 1996).
Coalescent Tradition.--The Coalescent Tradition is best described
as a time when massive population migrations were taking place. No one
has ever been able to establish how the Coalescent Tradition developed;
some claim the Middle Missouri Tradition people and Central Plains
Tradition people basically joined together and hence the term
Coalescent. It is thought that people coming in gradually blended with
groups already living along the Missouri River. Ceramics and lodges
within the villages reflect this view as houses of the period were
constructed in a square manner which is a trait associated with people
from the Central Plains Tradition, and in a circular manner which is a
trait associated with people from the Middle Missouri Tradition
(Zimmerman: 1985).
The Coalescent Tradition brought about the emergence of the Mandan,
Cheyenne, Dakota, Arikara, Kiowa, Siouan Ponca, and Omaha tribes and
traditions.
The Mandan.--At a point probably towards the end of the period, a
portion of the Miwat'a>ni began moving north up the Missouri River
eventually reaching the mouth of the Little Missouri River where the
group splits apart (Terrell: 1974). One group called Psaloka, ``Crow
Indians,'' moved southwest and settled in lands lying below the Rocky
Mountains. The other group returned to the Knife River area and
returning as they did the Miwat'a>ni begin calling them Minitari,
``Crossed the River.'' The Minitari are historically identified as
the Hidatsa. The Hidatsa and Crow kept their kin relation with each
other and Crow trading parties helped the Hidatsa people establish
numerous village sites in the Little Missouri and Yellowstone River
valleys (Terrill: 1974).
The Cheyenne.--One of the tribes sharing lands with the Dakota in
Minnesota was the Sahiyela, ``Red Talkers/Cheyenne Indians.'' They are
an Algonquian speaking people that migrated to the Minnesota River
valley after abandoning their homelands above Lake Superior to the
Chippewa (Grinnell: 1972) and established themselves along the
Minnesota River and the Yellow Medicine River. Their earth lodge
village at the Yellow Medicine River is called Sahiyela na wojupi,
``Where the Cheyenne Plant'' by the Dakota (Grinnell: 1972). When a war
between the Chippewa and Dakota broke out the Cheyenne began a westward
movement and ultimately abandoned their Minnesota and Yellow Medicine
river village sites. Dakota traditions about the Cheyenne never
indicate that warfare between the two tribes ever took place, but there
are recordings attributed to Stephan Riggs, and Lewis and Clark, that
indicate the Cheyenne were driven from the Minnesota River and the
Yellow Medicine River valley by the Dakota and the Chippewa (Grinnell:
1972). One element of the Cheyenne eventually settled along the south
bend of the Sheyenne River in the area of Lisbon, North Dakota
(Grinnell: 1972).
The Cheyenne villages in North Dakota were fortified and the people
grew crops and hunted bison. Their lodges were circular in form with
extended entryways usually facing southeast (Moore: 1996). The basic
floor plan of the lodge was similar to the other lodges constructed by
the Missouri River tribes. They were large circular structures
enclosing a central fire pit and built around four central support
posts (Grinnell: 1972). Other Cheyenne groups were nomadic hunters
after leaving Minnesota. They hunted and traded with the Mandan and
contrary to reports from Maximilian during the Missouri River travels
who claimed the two tribes engaged in a war, the Cheyenne and Mandan
people entered into and maintained friendly relations (Grinnell: 1972).
In the last part of the 18th and in the early part of the 19th century,
the Cheyenne were dispersed over a wide territory extending from west
of the Black Hills to the Missouri River, and from the Little Missouri
River towards its mouth, and as far south as the Arkansas river
(Grinnell: 1972). This wide dispersal was rewarding for the Mandan,
Arikara, and the Tito>wa> because the Cheyenne are the people that
brought horses into the Northern Plains (USACE 2004b).
The Dakota.--Circa A.D. 1500 to A.D. 1600, the Dakota at Bde
Waka> were engaging the Chippewa in a war for control of the marshy
wild rice lands lying between the Lake of the Woods in Canada and Lake
Superior and Lake Michigan. In the east the Iroquois began a period of
territorial expansion and conquest that drove the Chippewa into the
Dakota (Warren: 1984). The conflict between the tribes was a bloody one
with each side winning and losing numerous battles. At the time of the
war the Dakota were living as seven related bands, the Bde
Waka>to>wa>, ``Spirit Lake Village People;'' the Tito>wa>,
``Dwellers of the Plains;'' the Sisito>wa>, ``Slimy Ones;'' the
Wahpeto>wa>, ``Leaf Village People;'' the Wahpe kute, ``Leaf
Shooters;'' the Iha>kto>wa>, ``Camps on the End;'' and the
Iha>kto>wa>la, ``Little Camps on the End.'' To hold their lands the
Dakota formed an alliance known as the Oceti Sakowi>, ``Seven Council
Fires,'' to defeat the Chippewa (Walker: 1982) and for a time they
remained in control of the wild rice producing lands, but the formation
of the alliance eventually impacted all of the tribes occupying the
Missouri River (USACE 2004b).
The Arikara.--Throughout the 17th century the Arikara continued to
move up the Missouri River. The villages they constructed were earth
lodges encircling a central plaza and typically there was a large
ceremonial lodge facing the plaza area (Gilmore: 1930). Their lodges
were circular structures containing central hearths and large sub-floor
cache pits. Many of the villages had fortified palisades or ditch
entrenchments boarding them for protection (Ludwickson et al. 1987).
Lakota and Dakota traditions describe the Arikara occupation of the
Missouri River as expansive (LeBeau: 1994). Historically they may be
known as traders, but to the Lakota they were a powerful enemy who were
once considered relatives (Rice: 1994). They were the power in the
Missouri River basin until massive epidemics of diseases ravaged and
reduced their population after they came into contact with White people
(USACE 2004b).
The Kiowa.--The Kiowa are thought to have entered the Black Hills
region circa 1700 (Mayhill: 1971). They were a buffalo hunting people
and never developed an earthlodge farming culture. They did establish
trading relations with tribes in the area, primarily the Scili, Pawnee
and they often traveled along the Cheyenne and the Bad Rivers to trade
with the Arikara. When the first Oglala and Sicangu hunting bands
entered the Black Hills country, the Kiowa began fighting with them
over land and resources. A constant state of warfare between them and
the Lakota continued until the late 1700's when one of their sub-bands
were wiped out near the headwaters of the Cheyenne River by a large
Oglala war party (Mooney: 1898). This defeat forced the remaining
Kiowa to leave the region and move south into the southern plains
(USACE 2004).
The Ponca and Omaha.--The Siouan Ponca and Omaha are thought to
have entered the Missouri River region in the early part of the 18th
century. Near the mouth of the White River they established a camp
circa 1715 (Howard: 1995). The Ponca then moved on to the Black Hills
and traded with the Kiowa for a time, but for unknown reasons they
eventually migrated back to the White River camp and rejoined the
Omaha. Both tribes followed the river back to the south, returning to
the area around the mouth of the Niobrara River where they finally
established a permanent presence (Howard: 1995).
Typical Plains Village property types include occupations
(fortified and unfortified earthlodge villages), winter villages, camps
(hunting), flint quarries, eagle trapping sites and conical timber
lodges, burials, lithic workshops, bison kill sites, and rock art sites
(NDSHPO 2003).
Equestrian Nomadic
The Equestrian Nomadic tradition subsumes those lifeways that were
dependent upon horses during protohistoric and early historic times in
the Northern Plains. The introduction of the horse brought about
significant changes in subsistence strategies, demographics, social
organization, and settlement patterns. Known property types include
camps, battle sites, and animal kill sites (NDSHPO 2003).
3.2 Historic Period
The Historic period on the Missouri River is defined as the period
of first contact with non-Indians. During this period the Lakota were
the preeminent power in the project area until they were removed, along
with all of the tribes associated to the river basin area, to various
reservations in North Dakota and South Dakota. The Historic Period
consists of two parts: A.D. 1740 to 1804, the phase when the Lakota
rise to power within the Missouri River basin and displace the Arikara,
and A.D. 1804 to 1890, the phase when Indians lose control of the land
and are relocated to reservations.
The first portion of the historic period represents a time when
life along the Missouri River was in constant flux as the Lakota
started crossing the river in the middle of the 17th century. The
Arikara, the Mandan, and the Hidatsa have a well-established self-
sufficient, surplus-abundant trading system operating throughout the
Upper and Middle Missouri River region. The Mandan-Hidatsa villages
below the Knife River in North Dakota were visited annually by the
Cheyenne, Cree, Crow, Gros Ventre, and Yanktonai people who exchanged
tanned buffalo, deer and elk hides for agricultural goods and material
resources such as Knife River flint. The Arikara villages located at
the mouth of the Grand, Cheyenne, Bad, and White Rivers were visited
annually by the Cheyenne, Pawnee, Lakota and Dakota. The trade
intercourse throughout the plains revolved around these trading centers
and goods from the southwest, southeast, northwest, and northeast were
traded regularly between the tribes (Bowers: 1950; Wood & Thiessen:
1985).
By the 1790's the Lakota were roaming over a vast hunting territory
on both sides of the Missouri River as nomadic buffalo hunters.
Traditions state that once the Oglala drove the Kiowa out of the Black
Hills region the Lakota bands came together to hold a great council at
Bear Butte. During this council they formed their own tribal alliance,
which is also called the Oceti Sakowi>, ``Seven Council Fires''
(Plenty Chief: 1985). As the dominate power throughout the region, the
Lakota and their Dakota cousins in Minnesota quickly gained control
over a vast territory that stretched to the Teton Mountains in the
west, to the Minnesota River valley in the east. They maintained an
almost constant state of warfare with the Pawnee, Shoshone, Crow,
Blackfeet, Arikara, Mandan, Hidatsa, Cree and Plains Chippewa. By the
turn of the century in 1800 the Lakota controlled all of the lands
below the mouth of the Grand River that lie within the project area.
The Itazipco and the Mnikowoju bands were occupying the area between
the Bad and Cheyenne Rivers. The Hu>kpapa were in the area between the
Moreau and Grand Rivers, and the Siha Sapa and the Oohenu>pa were in
the area between the Cheyenne and Moreau Rivers (Hassrick: 1988). All
along the Missouri River bottoms the various bands erected seasonal
winter encampments, hunting camps and temporary trading camps where
they traded with each other. The Lakota became regular visitors to the
Big Bend area, holding councils with the Kul Wicasa and Yankton bands
who lived in the area. In the area around the Little Bend all of the
Lakota bands, several Yankton bands, and various Sisseton and Santee
Dakota bands held annual spiritual ceremonies and conducted individual
spiritual activities on a regular basis (LeBeau: 1994; 2002). Farther
up river in the area of Medicine Rock near the Little Cheyenne River,
the Lakota visited the site for ceremonial purposes, but it is also
considered an area where people could meet to trade with each other
(LeBeau: 1994).
The first eyewitness report recording contact occurring between the
Indians and non-Indians within the project area took place in 1743 when
the Verendrye brothers, Chevalier and Louis, entered the area and
traveled along the Cheyenne and Bel Fourche Rivers by canoe in an
attempt to find an overland route to the Pacific Ocean (Chittenden:
1986). In March of that year they returned to the area of the mouth of
the Bad River where they camped with a band of Arikara headed by Chief
Little Cherry. On March 30, 1743 the Verendryes went to a hill at the
junction of the Bad River with the Missouri and claimed the region for
France, and planted a lead plate as evidence of the claim (Schuler:
1990).
The second portion of the historic period consists of the
interaction between the first non-native people and the local tribes as
recorded by the early explorers, trappers, traders, military personnel,
and settlers.
In 1800 with the Louisiana Purchase the United States authorized a
series of official U.S. Army expeditions to explore their newly
acquired territory. In 1804 the Lewis and Clark Expedition entered the
area seeking to discover a water route leading to the Pacific Ocean.
The expedition sketched a map of the river attempting to list
intersecting rivers, creeks, streams, and physical features such as
prominent hills and buttes, Indian village sites, and expedition
camping sites (USACE 2004b).
In 1812 Fort Manuel was constructed along the west bank of the
Missouri River, 10 miles south of the present day North Dakota/South
Dakota border (Schuler 1990). The fort named after Manuel Lisa, a fur
trader from St. Louis, was the first trading post operating within the
project area. The fur trading business was booming and new forts were
erected to meet the need for trading with the local tribes. The success
of the fur trade operations along the upper Missouri created a need for
additional manufactured good to be traded to the local tribes for furs.
The establishment of the fur trade and the construction of trading
posts in the project area helped open up the territory to settlement by
homesteaders. By the time the fur trade was in full force the primary
occupants of the territory were the Lakota and Dakota Indians (Schuler:
1990). Once the settlers began entering the region conflicts between
them and the local native populations were inevitable. The Indian
tribes wanted white trade goods, but they did not want the white
settlers. Relations between the Indian tribes, specifically the Lakota
and Dakota, and the United States began deteriorating in the late
1820's and early 1830's.
Due to the influx of outsiders to the region new diseases spread
among the tribes decimating their populations. In 1837 a smallpox
outbreak on the Northern Plains reduced the Indian population by half
including seven-eighths of the Mandan and over 50 percent of the
Arikara populations (Dollar 1977). These disease outbreaks greatly
reduced the fur trade with the local indigenous people.
To secure trading rights with various Indian tribes the United
States Government began making treaties with the tribes as the westward
expansion into the Northern Plains took place. Invariably the treaty
processes also attempted to establish territorial limits for individual
Indian tribes and get them to acknowledge that the United States had
supremacy over them. Stipulations to protect the tribes from
depredations committed upon them by non-Indians not legally authorized
to enter their country for the purposes of trade or other views were
also included in the treaties that were made during this period. By the
1850's government treaties with the tribes in the Great Plains began
including additional language that dealt with the right of the United
States Government to establish roads, military and other posts within a
tribe's respective territory, as well as delineate a set boundary for
that territory (LeBeau: 1997). The United States failed to maintain its
treaty obligations with the tribes to keep non-Indians out of Indian
land and this failure more than any other factor is what caused
conflicts to break out that eventually resulted in the Missouri River
tribes being removed to permanent Indian reservations (LeBeau: 1997).
In 1851 the first Treaty of Fort Laramie was made by the United
States Government with the Sioux, Cheyenne, Arapaho, Crow, Assiniboine,
Gros Ventre, Mandan and Arikara tribes. This was an important event
because this treaty impacted all of the Indian tribes who resided in
the Missouri River basin running through the Dakotas. Under Article 5
in the treaty, physical boundaries delineating the territories of each
tribe are described and these physical descriptions provide indications
where tribal populations were located in 1851. In 1868 as a result of
Red Clouds War, a second Fort Laramie Treaty was made with the Sioux,
which established the Great Sioux Reservation and delineated its
physical boundaries. Again the descriptions provide an indication of
where tribal populations were located.
It was not just treaties the United States Government entered into
with Indian tribes living along the Missouri River. Agreements between
the Government and Indian tribes were also made, and in 1866 the United
States made the Fort Berthold Agreement with the Arikara, Mandan and
Hidatsa, which ceded land to the Government. In 1882-1883 the Agreement
with the Sioux of Various Tribes was made, and this agreement broke up
the Great Sioux Reservation and established 5 separate reservations for
the Sioux; those are Pine Ridge, Rosebud, Standing Rock, Cheyenne
River, and Lower Brule (USACE 2004).
The first military post in the region, Fort Pierre, was purchased
by the U.S. Army in 1855, but later abandoned in 1857 due to lack of
surrounding resources. In 1863 a second military installation, Fort
Sully, was established along the left bank of the Missouri River, 6
miles below Pierre, South Dakota. Fort Sully served as headquarters for
military troops stationed in the area, but was abandoned in 1866 and
relocated 34 miles upstream of the Missouri River approximately 30
miles below the confluence with the Cheyenne River (Frazer 1965).
Several additional military installations sprang up along the Plains of
the Missouri River drainages over the next few decades to include Fort
Rice in 1864, Fort Bennett in 1870, Fort Abraham Lincoln in 1872, and
Fort Yates in 1874 which remained a military post until 1903 (Frazer
1965).
In order to supply the military installations and trading posts,
steamboats were used to navigate the Missouri River. The steamboat era
was one of booming commerce, with many ships plying the major rivers of
the West. Steam operated wheel boats were used on the Missouri River as
early as late 1850s. By 1859 steamboats started to visit Fort Benton on
a regular basis. During the 1850s, Government contracts were issued to
companies willing to navigate the Missouri River to deliver annuities
to various Indian Tribes as required by treaty (Chittenden 1936;
Schuler 1990).
Steamboat travel was risky and dangerous since many of the inland
rivers were shallow during the summer, fall, and winter months. Paddle
wheelers were subject to accidents that could damage a cargo or destroy
the vessel. The Missouri River was especially dangerous due to its
shallow waters, swift currents, and narrow navigable channel. Many
paddle steamers perched their paddle-wheels on submerged sand bars,
often stranding the ship until high water returned the following
spring. In addition to the sandbars, numerous dead trees and snags
washed down stream within the channel and could puncture the bottom of
boats. By 1897 over 295 steamboat wrecks were recorded along the
Missouri River corridor; 193 of these wrecks were caused by dead trees
and snags (Chittenden 1897). Chittenden reports 11 steamboat wrecks
occurred along the North Dakota segment of the Missouri River alone
(Table 3-2).
TABLE 3-2.--SHIP WRECKS ALONG THE MISSOURI RIVER IN NORTH DAKOTA
------------------------------------------------------------------------
Year of
Name of Ship Wreck Location of Wreck
------------------------------------------------------------------------
Abner O'Neal....................... 1892 Painted Woods, North
Dakota
Amelia Poe......................... 1868 Near Little Porcupine
Creek
Assinniboine....................... 1835 Head of Sibley Island,
North Dakota
Behan.............................. 1884 Bismarck, North Dakota
Black Hills........................ 1884 Bismarck, North Dakota
Colonel McCloud.................... 1879 Bismarck, North Dakota
Denver No. 2....................... 1880 Fort Lincoln, North
Dakota
Emily No. 3........................ 1885 North of Bismarck,
North Dakota
Ida Stockdale...................... 1871 Bismarck, North Dakota
Island City........................ 1864 Below Fort Buford,
North Dakota
Rose Bud........................... 1896 Bismarck, North Dakota
------------------------------------------------------------------------
Source: Captain H. M. Chittenden's Report of the Chief of Engineers,
U.S. Army (1897).
By the mid 1880s, steamboat traffic ceased to exist. The completion
of the transcontinental railroad and subsequent railroad branches
replaced river traffic.
The early pioneer settlement of the Dakotas was directly influenced
by the construction of the railroads. The Dakota Central branch of the
Chicago & North Western Railroad built a track from Tracy, Minnesota to
Pierre, South Dakota during 1879 and 1880. In the 1880s during the
Great Dakota Boom (Robinson 1974) emigrants from Norway, Germany,
Russia, along with Midwestern groups in the United States, flooded into
Dakota Territory and the non-Indian population exploded with these
settlers coming in (USACE 2004b). New towns, farms, and rail lines
cropped up. The State's main economic base was primarily tied to
agriculture.
The last major event to occur that directly impacted the Native and
non-Native population living along the Missouri River was the
construction of the Pick-Sloan Reservoirs. The contemporary Missouri
River in North Dakota is highly modified from its natural character due
to the Flood Control Act of 1944. The Flood Control Act was Federal
legislation that led to the establishment of the Pick-Sloan Plan to
construct six large dams on the Missouri River main stem from Nebraska
to Montana. Closure of the Garrison Dam in 1953 and the Oahe Dam in
1958 and flooding the river bottom displaced thousands of people from
their homes. The cultural effects on the people that lived on the river
have never been adequately researched (LeBeau 1994).
Some of the historical and cultural sites that are open to tourists
include Fort Union Trading Post National Historic Site, Fort Buford
State Historic Site, Knife River Indian Villages National Historic
Site, Fort Clark State Historic Site, Double Ditch Indian Village State
Historic Site, and On-A-Slant Indian Village State Historic Site.
4.0 RESOURCE EVALUATION
4.1 Site Types and Known Resources
Berger assessed the potential types of cultural resources within
Burleigh, Emmons, Mclean, Morton, Oliver, Williams, Dunn, McKenzie,
Mercer, Mountrail, and Sioux Counties. The areas included USACE
jurisdiction areas at Lake Oahe and Lake Sakakawea, the Standing Rock
Sioux and Fort Berthold Reservations, as well as designated aggregation
areas of the Missouri River corridor. File searches were conducted by
USACE. File searches for private land along the main stem near the town
of Washburn were conducted through the State Historical Society of
North Dakota between January and March 2009. The list of legal
locations encompassed by the files and literature search is included in
Exhibit 1.
It should be noted that, while previous investigations have been
conducted, there are portions of the project area where no surveys have
been completed, particularly on private or tribal lands. Site types
encountered during the records search include prehistoric sites,
historic sites, multi-component sites (sites with both prehistoric and
historic materials), and sites that cannot be assigned to a specific
time period (``unknown'').
The research conducted by USACE revealed that prior investigations
have been undertaken within the aggradation areas; 148 sites have been
recorded within the Lake Oahe portion of the project area, and 1,216
sites have been previously recorded within the Lake Sakakawea portion
of the project area. The sites at Lake Oahe consist of 90 prehistoric,
31 historic, 17 multi-component, and 10 unknown sites. The sites at
Lake Sakakawea consist of 835 prehistoric, 120 historic, 54 multi-
component, 246 paleontological, and 205 unknown sites. The site
information for Lake Oahe is summarized in Table 4-1. The site
information for Lake Sakakawea is summarized in Table 4-2. To assist
the reader, a glossary of common archaeological terms in included in
Exhibit 2.
TABLE 4-1.--SITE TYPES WITH U.S. ARMY CORPS OF ENGINEERS JURISDICTION AT LAKE OAHE
----------------------------------------------------------------------------------------------------------------
Site Type Historic Prehistoric Unknown Number
----------------------------------------------------------------------------------------------------------------
Artifact Scatter............................. ............... ............... X 32
Buffalo Jump................................. ............... X ............... 1
Grave Sites.................................. ............... X X 2
Buried Bone Bed.............................. ............... X ............... 3
Camp/Ceramic Site............................ ............... X ............... 1
Dam.......................................... X ............... ............... 1
Dugout....................................... X ............... ............... 1
Earthlodge Village........................... ............... X ............... 42
Hearth/Lodge................................. ............... X ............... 13
Homestead.................................... X ............... ............... 19
Military Post................................ X ............... ............... 2
Mounds....................................... ............... X ............... 9
Rock Cairns.................................. ............... ............... X 1
Town site.................................... ............... X ............... 1
Community Center............................. X ............... ............... 1
Unknown...................................... ............... ............... X 15
------------------------------------------------------------------
TOTAL.................................. ............... ............... ............... 144
----------------------------------------------------------------------------------------------------------------
Of the 144 sites recorded at Lake Oahe, 123 sites are eligible for
inclusion in the National Register, and 21 sites remain unevaluated for
eligibility for the National Register.
TABLE 4-2.--SITE TYPES WITH U.S. ARMY CORPS OF ENGINEERS JURISDICTION AT LAKE SAKAKAWEA
----------------------------------------------------------------------------------------------------------------
Site Type Historic Prehistoric Unknown Number
----------------------------------------------------------------------------------------------------------------
Artifact Scatter............................. X X X 187
Buffalo Jump................................. ............... X ............... 3
Grave/Burial Sites........................... X X X 18
Buried Bone Bed.............................. ............... X ............... 2
Camp/Ceramic Site............................ ............... X ............... 2
Bridge....................................... X ............... ............... 2
Dugout....................................... X ............... ............... 39
Earthlodge Village........................... ............... X ............... 14
Hearth/Lodge................................. ............... X ............... 2
Homestead.................................... X ............... ............... 46
Military Post................................ X ............... ............... 2
Mounds....................................... ............... X ............... 2
Rock Cairns.................................. ............... X X 160
Town site.................................... ............... X ............... 8
Community Center............................. X ............... ............... 1
Cemetery..................................... X ............... ............... 13
Ceramic/Lithic Scatter....................... ............... X ............... 8
Church....................................... X ............... ............... 1
Eagle Trap................................... ............... X ............... 31
Quarry/mine.................................. X ............... ............... 4
Trail........................................ X ............... ............... 1
Indian Agency................................ X ............... ............... 1
Isolated Finds............................... ............... ............... X 71
Lithic Scatter............................... ............... X ............... 249
Mission...................................... X ............... ............... 1
Paleontological Localities................... ............... ............... ............... 246
Post Office.................................. X ............... ............... 1
Railroad Roundhouse Grade.................... X ............... ............... 1
Ranch........................................ X ............... ............... 3
Sacred Object................................ ............... X ............... 1
School....................................... X ............... ............... 3
Stone Circles................................ ............... X ............... 200
Stone Alignments............................. ............... X ............... 12
Teepee Rings................................. ............... X ............... 52
Trading Posts................................ X ............... ............... 3
Unknown...................................... ............... ............... X 70
------------------------------------------------------------------
TOTAL.................................. ............... ............... ............... 1,460
----------------------------------------------------------------------------------------------------------------
Of all sites recorded at Lake Sakakawea, the number of sites
eligible for inclusion in the National Register is 22. The number of
sites unevaluated for inclusion in the National Register is 1,194.
(Paleontological localities are not included in the numbers.)
The Three Affiliated Tribes (Mandan, Arikara, Hidatsa) at the Fort
Berthold Reservation currently does not maintain a database of sites
that could be searched. Therefore, there are no numbers available to
add to the site types.
The research conducted by the NDSHPO revealed that more than 70
sites have been previously recorded on private land portions subject to
aggradation along the main stem of the river within the project area.
This information is summarized in Table 4-3 below.
TABLE 4-3.--SITE TYPES PREVIOUSLY LOCATED WITHIN AGGRADATION AREAS ON PRIVATE LAND
----------------------------------------------------------------------------------------------------------------
Site Type Historic Prehistoric Unknown Number
----------------------------------------------------------------------------------------------------------------
Post Office.................................. X ............... ............... 4
School....................................... X ............... ............... 2
Church....................................... X ............... ............... 2
Farmstead.................................... X ............... ............... 11
Unknown Foundation........................... X ............... ............... 1
Unknown...................................... ............... ............... X 4
Trading Post................................. X ............... ............... 1
Artifact (Trash) Scatter..................... X ............... ............... 4
Pump House................................... X ............... ............... 1
Bridge....................................... X ............... ............... 6
Coal Mine.................................... X ............... ............... 1
Stone Circles................................ ............... X ............... 5
Earthlodge Villages.......................... ............... X ............... 5
Burials...................................... ............... X ............... 3
Artifact Scatters............................ ............... X ............... 26
------------------------------------------------------------------
TOTAL.................................. ............... ............... ............... 76
----------------------------------------------------------------------------------------------------------------
Of the 76 sites, 4 sites are eligible for inclusion in the National
Register; 4 sites are ineligible for inclusion in the National
Register; and 68 sites are unevaluated.
The NDSHPO lists 32 historic period context themes in the Statewide
Comprehensive Plan (NDSHPO 2003). Of the 32, at least 24 are pertinent
to projects that could be conducted by USACE to address siltation and
erosion, as well as other projects, along the Missouri River. Historic
site types, as defined by the NDSHPO (2003) that could be encountered
are:
--Bridges.--Relates to historical and/or design, engineering and/or
architectural values of bridges, grade separations, and
trestles.
--Colonization.--Relates to the planned and organized immigration,
settlement and/or resettlement of groups to, into, or within
North Dakota from other areas. Groups may be religious, social,
ethnic, or others, such as a Hutterite colony. Typical property
types may include: towns, colonies, settlements, reservations,
businesses, residences, and farms.
--Commerce.--Relates to the establishment, growth, and operations of
the sale or exchange of goods, including banking and financial
support services. Typical property types may include: trading
posts, retail stores, wholesale stores, general stores, banks,
savings and loan institutions, brokerage houses, mail order
houses, shipping and transportation facilities, and the homes
of prominent merchants, bankers.
--Communications.--Relates to the transmission of messages and
information. Typical property types may include: pow wow sites,
traditional cultural properties, newspaper offices, telegraph
and telephone facilities, post offices and mail stations, post
roads, radio, T.V. and microwave stations and towers.
--Depression--The Great.--Relates to the causes, effects of,
conditions during, and/or relief and recovery from the Great
Depression, 1929-1940. Typical property types may include:
abandoned farms, banks, business buildings, city parks, civic
improvements, relief facilities, WPA projects, Civilian
Conservation Corps (CCC) camps and project sites.
--Education.--Relates to the organized transmission of formal
knowledge, training and skills. Typical property types may
include: schools, boarding schools, colleges, universities,
business schools, trade schools, campuses, campus living
quarters, administration buildings, and homes of prominent
educators.
--Energy Development.--Relates to the establishment, development and
use of mechanical, hydro- and electrical power sources, their
generation, distribution and use. Typical property types may
include: water wheels, steam and/or electrical generating and
transmission facilities, dams, and power stations. This context
should not include coal or petroleum production facilities.
--Exploration.--Relates to the exploration, discovery, recording and
dissemination of information about the characteristics,
attributes, and values of the State. Typical property types may
include: trails, camp sites, camps, forts, battlefields,
storage yards, and the residences of prominent explorers.
--Farming.--Relates to the establishment and operation of farms.
Typical property types may include single or multiple
dwellings, barns, corrals, privies, dumps, grain storage,
animal shelters, indoor and outdoor storage facilities, and
water sources.
--Fur Trade.--Relates to the establishment, operation and adaptations
of the fur trade industry in North Dakota, particularly
(although not exclusively) from the late 18th to the late 19th
centuries. Typical property types may include, fur trading
posts and forts, trails, loading and shipping facilities,
trapping, trading and hunting grounds, camps and camp sites,
steamboat docks, stores, dwellings, warehouses, and residences
of prominent fur trade participants.
--Government--National.--Relates to the establishment and operation
of U.S. authority over, control of, and services to the area
within North Dakota's current boundaries. Typical property
types will generally include: Federal Government office
buildings, Federal courthouses, border stations, reservation
headquarters, customs houses, and post offices, but may also
occasionally include: mail stations, forts, trails, roads,
highways, camps, camp sites, and dwellings.
--Irrigation and Conservation.--Relates to the conservation and
planned use of land and water resources. Typical property types
may include: historically significant shelter belts,
conservation-oriented farming sites, pumping stations, water
pipelines, dams, reservoirs, canals, and flumes.
--Military.--Relates to all aspects of the military presence in the
State. Typical property types may include: forts, cantonments,
posts, Air Force installations, armories, battlefields, trails,
roads, bridges, fords, mail stations, cemeteries, villages,
camps, camp sites, dumps, defensive works, corrals, barns,
storage areas, and dwellings and residences.
--Railroads.--Relates to the establishment and operation of the
railroad industry in North Dakota. Typical property types may
include: railroad grades, bridges and trestles, depots, freight
yards, switch yards, barracks, dormitories, construction yards,
section houses, roundhouses, loading facilities, construction
camps, trails, camps, camp sites, office buildings, warehouses,
dumps, and signal devices.
--Ranching--Fee Simple.--Although similar to ``Open Range Ranching''
in general activities and products, important differences
separate this context from the other. Fee Simple Ranching is
characterized by the widespread use of privately owned, fenced
land. Usually intended to be permanent occupants of limited
space, these ranches were oriented towards continual re-use of
the natural resources, perpetuation and improvement of smaller
herds, were usually locally owned and financed, tended to
operate on a smaller scale and remain a part of the State's
agricultural economy. Typical property types may include:
single and multiple unit dwellings, barns, corrals, feed lots,
equipment storage yards and buildings, and wells.
--Religion.--Relates to the establishment and operations of religious
groups and institutions. Typical property types may include:
colonies, traditional cultural properties, shrines, holy
places, churches, synagogues, rectories, parsonages, church
schools and colleges, convents, and monasteries.
--Roads, Trails, and Highways.--Relates to the development and use of
overland transportation systems (excluding railroads) including
trails, roads, highways, automobile and truck traffic,
stagecoach and bus traffic and wagon routes. Typical property
types may include: trails, historically significant roads and
highways, bridges, fords, stage stations, rest stops, auto
dealerships, gasoline stations, freight yards, barns, relay
stations, maintenance shops, dwellings, repair shops, bus
depots, bus barns, and possibly camps, campsites, motels, inns,
and diners.
--Rural Settlement.--Relates to factors that influenced (or were
influenced by) settlement in rural areas including rural
institutions, rural industries (except farming and ranching),
ethnicity, colonization, and social institutions. Typical
property types may include: churches, factories, assembly
plants, brick making factories, roads-trails-highways, fords,
ferries, and river crossings, cemeteries, social gathering
places, rural schools, township halls, mills, forts, and
railroad properties.
--Water Navigation.--Relates to the commercial use of North Dakota's
lakes and rivers for transportation of goods and people. While
focusing on the steamboat industry, the context is intended to
include other forms of commercial water navigation, but to
generally exclude recreational boating. Typical property types
may include: steamboat docks, wharfs, piers, wood yards,
ferries, storage yards, freight yards, loading facilities,
wrecks or wreckage, boatyards, and dry docks.
5.0 DESCRIPTION OF IMPACTS
5.1 Current Land Use
The jurisdictional boundary of USACE is considered the shoreline
along Lake Oahe and Lake Sakakawea shown in Figure 1-1. The land use
around the reservoirs is primarily for USACE operations and maintenance
and public recreation. Between the two reservoirs is private and tribal
land. The land uses on the most of that reach of the river is
agricultural, ranching, recreation, and some community facilities
(e.g., Washburn).
5.2 Sources and Deposit Locations of Erosion and Sedimentation
For purposes of this assessment, the main stem of the Missouri
River is divided into four segments, each of which has the potential to
be affected by sedimentation and subsequent erosion. From north to
south, the segments are described below.
Williston Reach
The Missouri River between the Montana border and the upstream end
of Lake Sakakawea is generally referred to as the Williston reach. This
approximately 60-mile section of the Missouri River is not inundated by
a reservoir and the confluence with the Yellowstone River is within
this reach. When this sediment load meets the slow-moving headwaters of
Lake Sakakawea, it settles out and forms a delta.
Lake Sakakawea
Lake Sakakawea is a reservoir of approximately 286 kilometers in
length (Galat et al., 1996). It has a delta that is 61 kilometers in
length, formed by the deposition of sediment from the Williston reach
(Galat et al. 2005). Sakakawea's waters are colder, clearer, deeper,
and more hydrologically stable than what they would have been prior to
the construction of the dam.
Garrison Reach
Aside from the Williston reach, the Garrison reach, is the only
other section of the river in North Dakota that is not inundated by a
reservoir. However, this approximately 80-mile reach is controlled by
releases from Garrison Dam. The Garrison reach between Garrison Dam and
the headwaters of Lake Oahe is relatively deprived of sediment because
of the retention of sediment in Lake Sakakawea. Major sources of
sediment in this reach come from tributaries, not from the upstream
segments; among these tributaries, the Heart River is the most
important contributor of sediment (MacekRowland 2000).
Lake Oahe
Lake Oahe, formed by the Oahe Dam in South Dakota, is the longest
of the six Pick-Sloan Reservoirs, 372 kilometers in length (Galat et
al. 1996). Sediment import from the Garrison reach forms a delta 103
kilometers in length (Galat et al. 2005). Only a third of Lake Oahe is
located within North Dakota, with the remainder in South Dakota. Recent
drought conditions have changed the upstream reservoir sections from
flat water (typically at elevations above 1,600 to 1,608 feet msl) to
riverine characteristics that could affect cultural resource sites that
are exposed from falling water levels.
In the Identification of Sources and Deposits and Locations of
Erosion and Sedimentation report prepared for the USACE, Berger (2008)
found that:
--The majority of the identified aggradation areas were located
upstream of Lake Sakakawea in the close vicinity to the
Montana/North Dakota border and in the vicinity of watersheds
that showed large amounts of delivered land-based sediments. It
appears that the largest delivered sediment load originates
from Montana. The area between Garrison Dam and Lake Oahe
showed only one aggradation area. Potential sources for
sediment deposition were sediment erosion from upstream and
surrounding watersheds that have high potential of delivering
sediments.
--Areas that showed little or no aggradation were generally located
within the center of lakes (Lake Sakakawea and Lake Oahe), the
majority of the section between Garrison Dam and Lake Oahe, and
in the vicinity of watersheds that delivered considerable less
sediment.
5.3 Impacts on Indian and Non-Indian Sites
According to USACE and NDSHPO records of known Indian and non-
Indian sites along the reservoirs and main stem of the river within
potential areas of aggradation and erosion, USACE and other researchers
have recorded erosion, inundation, bioturbation, and effects of
farming, construction, and vandalism. Table lists observations of
impacts at Lake Oahe, and Table lists observations at Lake Sakakawea.
TABLE 5-1.--IMPACTS OCCURRING ON SITES AT LAKE OAHE
------------------------------------------------------------------------
Number of
Impacts Sites Impacted
------------------------------------------------------------------------
Cut bank Erosion........................................ 34
Unspecified Erosion..................................... 7
Shoreline Erosion....................................... 7
Complete Inundation..................................... 10
Partial Inundation...................................... 7
Periodic Inundation..................................... 8
Decay/weathering........................................ 2
Razed................................................... 10
Cultivation............................................. 22
Bioturbation............................................ 1
Recreation.............................................. 2
Railroad Construction................................... 2
Vandalism/unauthorized Collection....................... 3
Vehicular Movement...................................... 8
Unknown................................................. 7
---------------
TOTAL............................................. 130
------------------------------------------------------------------------
TABLE 5-2.--IMPACTS OCCURRING ON SITES AT LAKE SAKAKAWEA
------------------------------------------------------------------------
Number of
Impacts Sites Impacted
------------------------------------------------------------------------
Cut bank Erosion........................................ 74
Unspecified Erosion..................................... 111
Shoreline Erosion....................................... 108
Complete Inundation..................................... 85
Partial Inundation...................................... 8
Periodic Inundation..................................... 12
Siltation/buried........................................ 59
General Disturbance..................................... 19
Absent.................................................. 139
Authorized Archaeological Collection.................... 22
Grazing................................................. 51
Deflation............................................... 8
Development............................................. 1
Decay/weathering........................................ 29
Razed................................................... 14
Cultivation............................................. 68
Landscape Construction.................................. 11
Military Activity....................................... 7
Moved................................................... 3
Overgrown............................................... 23
Bioturbation............................................ 24
Recreation.............................................. 95
Railroad Construction................................... 15
Vandalism/Unauthorized Collection....................... 13
Vehicular Movement...................................... 83
Other................................................... 28
Unknown................................................. 93
---------------
TOTAL............................................. 1,203
------------------------------------------------------------------------
Natural or human-caused impacts to Indian and non-Indian sites can
be direct or indirect.
Direct Impacts.--Those impacts that would be caused by deposition
of silt and sediment, flooding, erosion caused by waves or changes in
reservoir levels, and ground surface disturbance during construction
projects associated with siltation remediation (such as rip-rap
placement).
Indirect Impacts.--Those impacts that would be caused by factors
associated with increased agency, tribal, or public access to site
locations. These could include inadvertent ground disturbance,
vandalism, or changes to the viewshed.
Several studies of the effects of reservoir construction and
inundation of cultural resources have been conducted (e.g., Carrell et
al. 1976; Adivasio 1980; Lenihan et al. 1981a, 1981b; Fairley 2003).
There are four basic reservoir areas that are important to
understanding effects to cultural resources (USACE 2002): (1) The
Inundation Zone--the main body of water making up a reservoir excluding
its lateral edges; (2) Zone of Fluctuation--the reservoir area where
water levels range between high water to low water marks and includes
land not always under water; (3) Zone of Direct Impact--the reservoir
area where cultural resources are located and potentially in contact
with water levels; and (4) Zone of Indirect Impact--the land adjacent
to a reservoir that is not exposed to inundation.
The impacts of siltation and erosion on cultural resources occur in
the Inundation Zone, Zone of Fluctuation, and Zone of Direct Impact,
while (as expected) indirect impacts occur most frequently in the Zone
of Indirect Impact.
While siltation can effectively and beneficially protect and
preserve some sites, such as subsurface archaeological sites, often the
subsequent wind or water erosion is destructive. Recent drought
conditions have resulted in lower than normal lake levels in Lake Oahe
changing the upstream character of the reservoir from a reservoir to
that of riverine character. Of particular concern is cut bank erosion.
Archaeological sites and historic structures along reservoir and river
banks can slowly or drastically erode away as the shoreline erodes.
Indian and other ethnic group traditional use or ceremonial areas, also
known as TCPs, can be affected by both siltation (covering the resource
or area) and erosion (depleting the resource or area). Other factors
potentially destructive to cultural resources are agricultural and
grazing leases close to the USACE jurisdictional boundary (Gilbert
personal communication 2009). Because Indian and non-Indian sites
resources are non-renewable resources, almost all impacts as a result
of siltation and erosion are considered adverse or negative. In
cultural resource terms, the integrity, or composition and
cohesiveness, of a site is crucial to a site's significance and
intrinsic value to understanding our history or prehistory. The
magnitude of the impact to the integrity of a site can vary from minor
(e.g., artifact displacement resulting from sediment movement) to
substantial (e.g., complete removal of a stone circle, stone cairn, or
structural foundation resulting from an erosion event).
6.0 SUMMARY AND RECOMMENDATIONS
Cultural resources are considered a non-renewable resource that can
be lost forever when destroyed. For Indian and non-Indian historical
and cultural sites, the primary recommendation is to provide mitigation
of impacts resulting from the cycle of siltation and erosion.
Mitigation is defined as avoiding or lessening impacts to significant
resources. Mitigation measures for the types of adverse impacts listed
in Section 5.3 can range from cultural resource inventories, to regular
periodic monitoring of known sites, to full-scale excavation and data
recovery. Measures to be taken would depend on the type, context,
character, setting, size, complexity, and other characteristics of the
individual resources. Cultural resource inventory projects identifying
surface sites, features, and standing structures are usually considered
short-term measures, although pedestrian surveys may need to be
repeated as environmental or site conditions change over time. Other
more long-term measures can consist of fencing for avoidance,
monitoring during ground-disturbing activities, and stabilization of
stream banks or building foundations.
Long-term, periodic monitoring of the condition of surface and
subsurface cultural resources should be done by prehistoric or
historical archeologists. Monitoring of standing structures should be
done by architectural historians. Should full-scale excavation be
needed to retrieve scientific data that are in danger of being lost
from development or fluctuation of water levels, the duration would
depend on the surface extent and depth of the cultural material; in
other words, how big is the site and how deep does it extend below the
ground surface? This would be considered a short-term project compared
to monitoring. All work should be performed by specialists whose
credentials meet or exceed the Secretary of Interior's Professional
Qualifications Standards.
Table 6-1 and Table 6-2 list future actions and mitigation measures
recommended in the USACE site database for known Indian and non-Indian
sites at Lake Oahe and Lake Sakakawea.
TABLE 6-1.--RECOMMENDATIONS BY THE U.S. ARMY CORPS OF ENGINEERS AT LAKE
OAHE
------------------------------------------------------------------------
Number of
Recommendation Sites
------------------------------------------------------------------------
Monitor at Low Water Levels............................. 4
More Research Required.................................. 1
Test for NRHP Eligibility............................... 62
Re-evaluate Site........................................ 9
No Further Work Needed--Completely Inundated............ 10
No Recommendation Available............................. 18
Other (Unspecified)..................................... 17
------------------------------------------------------------------------
TABLE 6-2.--RECOMMENDATIONS BY THE U.S. ARMY CORPS OF ENGINEERS AT LAKE
SAKAKAWEA
------------------------------------------------------------------------
Number of
Recommendation Sites
------------------------------------------------------------------------
Monitor at Low Water Levels............................. 2
Monitor for Erosion and Vandalism....................... 35
More Research Required.................................. 3
Protect or Mitigate..................................... 39
Test for NRHP Eligibility............................... 140
Re-evaluate Site........................................ 840
No Further Work Needed--Completely Inundated............ 79
No Recommendation Available............................. 64
Other (Unspecified)..................................... 14
------------------------------------------------------------------------
A further recommendation would be to prepare a regional research
design for the study of cultural resources as was done for the Colorado
River in Arizona (Fairley 2003). The purpose of the design would be to
guide future research at Indian and non-Indian historical and cultural
sites affected by the Missouri River in North Dakota. The objective
would be to provide a framework for management and treatment of
cultural resources under the jurisdiction of USACE.
Table 6-3 contains a summary of impacts, a timeline, and
recommendations for managing Indian and non-Indian sites along the
Missouri River in North Dakota.
Some of the recommendations can be implemented by various parties
of the Task Force. For example, the State of North Dakota can conduct
public education on the importance of preservation of historical and
other cultural sites, which can help prevent intentional and
unintentional vandalism. Local and private recreational entities can
construct and operate facilities with respect for historical and
cultural sites along the river. The Standing Rock Sioux Tribe and the
Three Affiliated Tribes can continue to monitor archaeological sites
and other sensitive areas that are in danger from siltation and
erosion. The USACE can limit the range of agricultural and grazing
leases to avoid sensitive areas.
These recommendations can be promoted by all members of the Task
Force. Appreciation and understanding of the non-renewable nature of
cultural resources is the key to managing cultural resources. All
parties can be included as stakeholders in the development of a
research design and plan for the treatment of Indian and non-Indian
historical and cultural sites.
TABLE 6-3.--SUMMARY OF IMPACTS AND RECOMMENDATIONS
----------------------------------------------------------------------------------------------------------------
Impact Significance Timeline Recommendation
----------------------------------------------------------------------------------------------------------------
Inundation (partial, periodic, Substantial........... Long-term--for life of Monitorat low water
complete). jurisdiction. levels; data recovery as
needed
Erosion (cut bank, shoreline, Substantial........... Long-term--for life of Monitor for erosion;
general). jurisdiction. stabilize if needed; data
recovery as needed
General Disturbance................ Moderate.............. Long-term--for life of Monitor; data recovery as
jurisdiction. needed
Agriculture........................ Minor--Moderate....... Long-term--for life of Protect or mitigate with
lease. fencing, testing, or data
recovery
Grazing............................ Minor--Moderate....... Long-term--for life of Protect or mitigate with
lease. fencing, testing, or data
recovery
Construction....................... Substantial........... Short-term--up to 1 Protect or mitigate with
year as project fencing, testing, or data
progresses. recovery
Recreation......................... Moderate.............. Long-term--for life of Monitor for activity and
jurisdiction. vandalism; fence as
needed
Vandalism.......................... Moderate.............. Long-term--for life of Monitor for activity and
jurisdiction. vandalism; fence as
needed
All................................ Minor--Substantial.... Short-term (1 to 5 Prepare research design
years). for cultural resources
along the Missouri River
in North Dakota
----------------------------------------------------------------------------------------------------------------
7.0 REFERENCES CITED AND BIBLIOGRAPHY
Adovasio, J.M., J. Donahue, W.C. Johnson, J.P. Marwitt, R.C.
Carlisle, J.D. Applegarth, P.T. Fitzgibbons and J.D. Yedlowski. 1980.
An inundation study of three sites in the Bluestone Reservoir, Summers
County, West Virginia. In The final report of the national reservoir
inundation study volume II, edited by D.J. Lenihan.
Carrell, T., S. Rayl and D. Lenihan. 1976. The Effects of
Freshwater Inundation of Archaeological Sites through Reservoir
Construction: Literature Search. On file at the United States
Department of the Interior, National Park Service, Cultural Resources
Management Division, Archaeology, Washington.
Chittenden, Martin Hiram. 1936. The American Fur Trade of the Far
West. 2 vols. Rufus, Rockwell, Wilson, New York.
Dahlberg, James C.; Whitehurst, John C. 1990. An overview of Souris
River basin prehistory in North Dakota. Journal of the North Dakota
Archaeological Association 4:76-110.
Fairley, Helen. 2003. Changing River: Time, Culture, and the
Transformation of Landscape in the Grand Canyon. A Regional Research
Design for the Study of Cultural Resources along the Colorado River in
Lower Glen Canyon and Grand Canyon National Park, Arizona. Prepared for
the U.S. Geological Survey. Statistical Research, Inc. Technical Series
79.
Fortier, Andrew C., Thomas E. Emerson, and Fred A. Finney 1984.
Early Woodland and Middle Woodland Periods. In American Bottom
Archaeology, edited by Charles J. Bareis and James W. Porter, pp. 59-
103. University of Illinois Press, Urbana.
Galat, D.L., J.W. Robinson, and L.W. Hesse. 1996. Restoring Aquatic
Resources to the Lower Missouri River: Issues and Initiatives. In
galat, D.L., and Frazier, A.G. (eds.), Overview of River-Floodplain
Ecology in the Upper Mississippi River Basin, v.3 of Kelmelis, J.A.,
ed., Science for Floodplain Management into the 21st Century:
Washington, DC, U.S. Government Printing Office, p. 73-92.
Galat, D.L., C.R. Berry, E.J. Peters, and R.G. White. 2005.
Missouri River Basin. In A.C. Benke and C.E. Cushing (editors). Rivers
of North America. Oxford: Elsevier.
Gilbert, Steve. 2009. Personal communication, Steve Gilbert, USACE
Archaeologist, Riverdale office, via telephone with Lucy Bambrey, The
Louis Berger Group. March 12, 2009.
Lenihan, D., T.L. Carell, S. Fosberg, L. Murphy, S.L. Rahl and J.A.
Ware. 1981a. The Final Report of the National Reservoir Inundation
Study Volume I. On file at the United States Department of the
Interior, National Park Service, Southwest Cultural Resources Center,
Santa Fe.
Lenihan, D., T.L. Carell, S. Fosberg, L. Murphy, S.L. Rahl and J.A.
Ware. 1981b. The Final Report of the National Reservoir Inundation
Study Volume II. On file at the United States Department of the
Interior, National Park Service, Southwest Cultural Resources Center,
Santa Fe.
Macek-Rowland, K. 2000. Suspended Sediment Loads from Major
Tributaries to the Missouri River Between Garrison Dam and Lake Oahe,
North Dakota, 1954-98. U.S. Geological Survey Scientific Investigations
Report 00-4072.
North Dakota State Historic Preservation Office (NDSHPO). 2003.
Historic Preservation in North Dakota, II: A Statewide Comprehensive
Plan. Historic Preservation Division, State Historical Society of North
Dakota. Bismarck, ND.
Schuler, Harold H. 1990. Fort Pierre Chouteau. University of South
Dakota Press. Vermillion, South Dakota.
State Historical Society of North Dakota. 1996. The Centennial
Anthology of North Dakota History: Journal of the Northern Plains.
Edited by Janet Daley Lysengen and Ann Rathke. State Historical Society
of North Dakota. Bismarck, ND.
The Louis Berger Group, Inc. (Berger). 2008. Identification of
Sources and Deposits and Locations of Erosion and Sedimentation.
Prepared for U.S. Army Corps of Engineers Omaha District and The
Missouri River Joint Water Board. August 2008.
U.S. Army Corps of Engineers. 2002. Final Lower Snake River
Juvenile Salmon Migration Feasibility Report/Environmental Impact
Statement. Appendix N--Cultural Resources. U.S. Army Corps of
Engineers, Walla Walla District.
U.S. Army Corps of Engineers. 2004a. Jurisdictional Determination
for Lake Oahe. U.S. Army Corps of Engineers, Omaha District. September
16, 2004.
U.S. Army Corps of Engineers. 2004b. Final Cultural Resources
Management Plan Lake Oahe, South Dakota. U.S. Army Corps of Engineers,
Omaha District. September 2004.
U.S. Army Corps of Engineers. 2006a. Jurisdictional Determination
for Lake Sakakawea. U.S. Army Corps of Engineers, Omaha District. April
26, 2006.
U.S. Army Corps of Engineers. 2006b. Final Cultural Resources
Management Plan Lake Sakakawea, North Dakota. U.S. Army Corps of
Engineers, Omaha District and Three Affiliated Tribes. April 2006.
U.S. Army Corps of Engineers. 1897. Report of the Chief of
Engineers, Appendix D. U.S. Army. Capt. H.M. Chittenden, Missouri River
Commission. June 30, 1897.
Wood, Raymond W. and Margot Liberty. 1980 Prehistoric Studies on
the Plains. Chapter 5 in Anthropology on the Great Plains, edited by
Lincoln: University of Nebraska Press, pp. 35-50 (Alfred E. Johnson,
senior author). Plains Trade in Prehistoric and Protohistoric
Intertribal Relations. Chapter 6, ibid.: 98-109.
Wood, Raymond W. 1980. The Origins of the Hidatsa Indians: A Review
of Ethnohistorical and Traditional Data. [Published 1986.] Midwest
Archeological Center, Lincoln, Nebraska.
Zimmerman, Larry J. 1985. Peoples of Prehistoric South Dakota.
University of Nebraska Press, Lincoln.
exhibit 1--legal sections in files and literature search
The research area search encompasses all or parts of the following
sections:
Township 130N Range 80W Sections 1, 3, 10-15, 22-26
Township 130N Range 79W Sections 19, 30, 31
Township 137N Range 80W Sections 16, 17
Township 137N Range 79W Sections 7, 8, 18
Township 134N Range 79W Sections 2, 11
Township 153N Range 102W Sections 9-30, 33-36
Township 152N Range 102W Sections 5, 6
Township 153N Range 103W Sections 24
Township 154N Range 101W Sections 21-24, 28, 29
Township 153N Range 102W Sections 12, 13, 24, 25, 36
Township 153N Range 101W Sections 18, 19, 30
Township 154N Range 100W Sections 19, 29
Township 154N Range 97W Sections 2, 3, 10, 11, 14, 15
Township 155N Range 96W Sections 31, 32
Township 154N Range 96W Sections 2-10, 15-18, 20
Township 154N Range 97W Sections 1, 2, 11-14
Township 155N Range 97W Sections 36
Township 154N Range 96W Sections 1-3, 11-13
Township 154N Range 95W Sections 18
Township 154N Range 94W Sections 32-35
Township 154N Range 94W Sections 36
Township 144N Range 83W Sections 13, 14, 22-27, 34, 35
Township 144N Range 82W Sections 8, 9, 18-30, 33-36
Township 143N Range 82W Sections 1, 2
Township 144N Range 81W Sections 29-32
Township 143N Range 81W Sections 6
Township 134N Range 79W Sections 14, 15, 23, 26, 35, 36
Township 133N Range 79W Sections 1, 2, 12, 13, 24-26, 34, 35
Township 132N Range 79W Sections 4, 5, 9, 16
Township 131N Range 79W Sections 7, 18
Township 131N Range 80W Sections 12-14, 23-25, 35, 36
Township 132N Range 79W Sections 15, 16, 28, 32, 33
Township 131N Range 79W Sections 5, 7, 8, 18
Township 131N Range 80W Sections 35, 36
Township 130N Range 80W Sections 1-3, 10-15, 22-26, 36
Township 130N Range 79W Sections 6, 7, 18, 19, 30, 31
Township 129N Range 80W Sections 1
Township 129N Range 79W Sections 4-6, 8-10, 14, 15, 22, 23, 25-27,
35, 36
Township 152N Range 93W Sections 9, 11, 14-16, 20-23, 27-33
Township 151N Range 93W Sections 5-8, 16-20, 30, 31
Township 151N Range 94W Sections 25, 26, 35, 36
Township 151N Range 93W Sections 30, 31
Township 150N Range 92W Sections 13, 14, 23-26, 35, 36
Township 150N Range 91W Sections 18, 19, 30-32
Township 149N Range 92W Sections 1, 2
Township 149N Range 91W Sections 6
Township 148N Range 91W Sections 14-17, 20-23
Township 148N Range 90W Sections 20-23, 27-29
exhibit 2--glossary of archaeological terms
Analysis.--The process of studying and classifying artifacts,
usually conducted in a laboratory after excavation has been completed.
Archaeology/archeology.--The scientific study of past human
cultures by analyzing the material remains (sites and artifacts) that
people left behind.
Archaeological Site.--A place where human activity occurred and
material remains were deposited.
Artifact.--Any object made, modified, or used by people.
Assemblage.--Artifacts that are found together and that presumably
were used at the same time or for similar or related tasks.
Attribute.--A characteristic or property of an object, such as
weight, size, or color.
B.P.--Years before present; as a convention, 1950 is the year from
which B.P. dates are calculated.
Ceramic.--Pottery, fired clay.
Chronology.--An arrangement of events in the order in which they
occurred.
Classification.--A systematic arrangement in groups or categories
according to criteria.
Context.--The relationship of artifacts and other cultural remains
to each other and the situation in which they are found.
Culture.--A set of learned beliefs, values and behaviors--the way
of life--shared by the members of a society.
Debitage.--The by-products or waste materials left over from the
manufacture of stone tools.
Diagnostic Artifact.--An item that is indicative of a particular
time period and/or cultural group.
Excavation.--The systematic digging and recording of an
archaeological site.
Experimental Archaeology.--Scientific studies designed to discover
processes that produced and/or modified artifacts and sites.
Feature.--A type of material remain that cannot be removed from a
site such as roasting pits, fire hearths, house floors or post molds.
Grid.--A network of uniformly spaced squares that divides a site
into units; used to measure and record an object's position in space.
In Situ.--In the original place.
Level.--An excavation layer, which may correspond to natural
strata. Levels are numbered from the top to bottom of the excavation
unit, with the uppermost level being Level 1.
Lithic.--Stone, or made of stone.
Material Remains.--Artifacts, features and other items such as
plant and animal remains that indicate human activity.
Midden.--An area used for trash disposal.
Post Mold/Post Hole.--A type of feature; a circular stain left in
the ground after a wooden post has decayed; usually indicates the
former existence of a house or fence.
Pot Sherd.--A piece of broken pottery.
Prehistoric.--The period of time before written records; the
absolute date for the prehistoric period varies from place to place.
Projectile Point.--A general term for stone points that were hafted
to darts, spears or arrows; often erroneously called ``arrowheads''.
Rock Art.--A general term for pecked, incised, or painted figures
on rock.
Site.--A place where human activity occurred and material remains
were deposited.
Site Steward.--A volunteer who visits a site and helps protect it
form vandalism and looting.
Strata.--Many layers of earth or levels in an archaeological site
(singular stratum).
Stratigraphy.--The layering of deposits in archaeological sites.
Cultural remains and natural sediments become buried over time, forming
strata.
Survey.--The systematic examination of the ground surface in search
of archaeological sites.
Test pit.--A small excavation unit dug to learn what the depth and
character of the stratum might be, and to determine more precisely
which strata contain artifacts and other material remains.
exhibit 3--environmental compliance requirements
There are several statutes, regulations, executive orders, and
Department of Defense regulations, USACE policies and procedures that
require USACE to take into account the effects of a proposed action or
program on cultural resources. These include, but are not limited to:
--National Historic Preservation Act (NHPA), 1966
--Advisory Council on Historic Preservation (ACHP)--Protection of
Historic Properties--36 CFR 800
--Native American Graves Protection and Repatriation Act (NAGPRA),
1990
--American Indian Religious Freedom Act (AIRFA), 1978
--Archeological Resources Protection Act (ARPA), 1979
--Executive Order 11593--Protection and Enhancement of the Cultural
Environment, 1971
--Executive Order 13007--Sacred Sites, 1996
--Executive Order 13175--Consultation and Coordination with Indian
Tribal Governments, 2000
--National Environmental Policy Act of 1969 (NEPA)
--Archeological and Historic Preservation Act of 1974 (AHPA),
amending Reservoir Salvage Act of 1960
--Abandoned Shipwreck Act of 1987
--Army Regulation (AR) 200-4 Cultural Resources Management
--USACE Rules and Regulations Governing Public Use of Water Resources
Development Projects--36 CFR 327
Compliance with the above listed items ranges from inventory and
consideration of cultural resources (Indian and non-Indian) by Federal
agencies in project planning to monetary fines for destruction, theft,
or vandalism of cultural sites.
Mr. Gunsch. Just a couple following examples taken from
this report and tables are attached to my testimony.
Table 2.13, the Flood Plain Area Comparison, the difference
between the 1985 and the 2005 mapping which showed an increase
in flooding within the Bismarck city limits from 2.7 to 3.6
square miles. And within Burleigh County it increased from 28
to 36 square miles which is an increase of 28.6 percent. That
is concerning.
Appendix F is impacts of siltation on flood control.
Table 3.1 Flood Elevation Comparison, that goes back to the
elevations I discussed earlier on the increases in elevations
which in the Fox Island area between that 17 year period was
about a foot. So the base flood elevations have increased
significantly.
The question at this point is what can be done?
Interestingly enough there's been a review of the Berger
Report. Table 7 includes recommendations for addressing
sedimentation impacts along the Missouri River in North Dakota
under flood risks. In the Bismarck/Mandan area there are four
key items.
I have listed them.
Their tradeoff analysis of the flood control is basically
development restrictions or flow restrictions.
No. 2, study impacts of sedimentations of flood risk when
the Oahe reservoir is full.
Three is develop strategies for mitigating ice affected
flooding exacerbated by sediment deposition at the headwaters
of Lake Oahe.
Four is conducting debris and snag removal in the Heart
River confluence area.
The timeframe to complete these project study items ranges
from short term to 3 to 5 years with a total cost combined for
all of them is between $2 and $4.2 million. These are not
inclusive of the elements that are currently being reviewed by
the Water Resource Districts. Therefore additional costs remain
to be identified.
The fourth item on that particular table study list had to
do with the conducting removal of debris and tree or dead fall
trees in the Heart River area. The remnants from that 2009
flood will become increasingly more difficult to remove once
they're entrapped by additional river sediments. A flood hazard
mitigation grant was filed or an application was filed with the
North Dakota division of Emergency Management in July 2009. And
the estimated costs of that work was about $430,000. We've
included a copy of the risk assessment for that particular
project as part of our testimony.
[The information follows:]
Missouri River Flood Hazard Mitigation--Bismarck/Mandan Project Summary
and Risk Assessment--Deadfall Tree Removal Grant Application
project description
The deposition of fallen trees (deadfall) within the bed and along
the banks of the Missouri River, during the April 2009 flood event,
represents a significant increase in the potential flood hazard in this
reach. These trees were carried into and deposited within the river
channel as a result of significant bank erosion, channel shifts and ice
flows. They range from 18 inches to 48 inches in diameter and from 20
to 60 feet in length. The number of deadfall trees varies by location,
but they are heaviest on the upstream edge of existing or newly formed
sandbars, along the eroded river banks lined with native forest, and
along the shallower channel areas.
In addition to the deposition of the deadfall trees the 2009 flood
resulted in the deposition of a significant amount of sediment
generated by the Heart River, bed and banks of the Missouri River and
other upstream tributaries. Some of these sand bars represent new
deposition, while existing sandbars were increased in both elevation
and width.
Since the deadfall trees are large and numerous, given projected
river flows as well as the high Oahe Reservoir elevation, it is
unlikely they will be transported downstream by normal runoff. As a
result they represent a considerable and avoidable risk for the
continued accumulation of sediments downstream from the Heart River
confluence. This is commonly referred to as the Oahe Delta and was the
location of the 2009 ice jam that flooded South Bismarck, Fox Island
and areas with the city of Mandan. The net effect of these trees is
much like that of a snow fence as waters continue to flow around them
and sediment deposition increases. Once these trees are submerged by
sediment they become entrapped, semi permanent and will not move
downstream without significant shifts in the river channel. In addition
the sediments they collect will also not be flushed downstream into the
Oahe Reservoir.
Additional depths from 2 to 3 feet are anticipated to occur within
these areas, which will result in a measurable reduction in the
available floodway conveyance within the Missouri River channel. This
additional deposition will eventually convert the character of the new
sand bars from unvegetated to vegetated, and then from vegetated to
vegetated, with extended trees and brush. This sandbar growth, which
again is part of the Oahe Delta formation, will then further restrict
open channel conveyance thus creating shallower areas. During winter
and spring flows this significantly increases the risk for ice jams
resulting in potential for backwater flooding and bank erosion.
The location of the Oahe Delta within the Missouri River Floodway
creates a number of primary flood hazards. The first is a continuing
increase in the Base Flood Elevation (BFE) on the Missouri River and
the associated flood risks in South Bismarck, Fox Island Area and the
city of Mandan. The increase in BFE from 0.8 to 1.0 foot between the
1985 and 2005 FIRM's documents this situation and raises significant
concern. The additional sediment deposited by the 2009 flood has
compounded this increase, though an evaluation of the extent of this
impact remains to be quantified.
A second significant hazard is the blocking of the Heart River's
confluence into the Missouri River and the increased risk for localized
ice jams in this area. Such ice jams pose a risk not only to create
upstream backwater flooding, but also impacts to and the potential
failure of the Heart River levee system protecting the city of Mandan.
While the risk of a given event occurring during the current blockage
by sediment and trees might be probability based it cannot be taken
lightly given recent events. Subsequently, proactive action is
necessary to alleviate and mitigate this known flood hazard.
A third hazard is the substantial growth of new and existing
sandbars within the Missouri River channel and floodway that restrict
not only the flow of open water, but increase the risk for ice jams.
The 2009 ice jam occurred within the first 2 miles south of the Heart
River confluence and was caused by a combination of factors. One was
the restriction of flows within the Missouri River channel due to
existing sandbars and new sediment deposited by the event itself. Any
additional restriction of the channel conveyance by trees and further
sediment deposition needs to be addressed in a timely manner.
After reviewing the extent and nature of the debris deadfall trees
and sediment deposition within the bed of the Missouri River south of
the Heart River Confluence consideration was given to the need to
remove and dispose of these trees. The future removal of the prior and
recent sediment deposition within this area is being addressed
separately and is not included in nor part of this application.
When considering the project scope several factors had to be
weighed as they relate to direct or indirect impacts and flood hazards.
Generally the primary impact area for deadfall trees is located within
a few miles of the Heart River confluence, Missouri River Mile 1311.5
to 1307. The deadfall in this reach has the greatest potential to
increase the risk and frequency of ice jams and backwater flooding.
Areas further south, while having an impact on the overall growth and
expansion of the Oahe Delta, were not deemed as critical as this
southern area is located more in the headwaters of the Oahe Reservoir.
In addition deadfall trees located along the eroded shoreline were
excluded from the proposed removal project as they are presently acting
as a buffer and natural stabilization measure to limit future bank line
losses.
project purpose
The proposed project is located entirely within the Missouri River
floodway. Its purpose is to prevent the future deterioration and loss
of flow conveyance associated with the deadfall trees and future
sediment accumulations. The project requires the collection, cutting,
loading, hauling and disposal of deadfall trees at an offsite location.
The removal process requires the contractor to use several barges and a
tug boat to haul equipment along the river channel and onto the
sandbars to collect, cut, load and haul deadfall trees to an area where
they would be transported to a disposal site. The deadfall trees within
the river would be loaded by crane onto the barge or towed upstream
using the tugboat to an off load point along the river bank. The larger
deadfall on the sandbars would be cut into sections suitable for
collection then loaded onto the barge for transport and disposal.
Both aerial and ground photos were taken to document the
approximate location and extend of deadfall trees within and along the
river. A ground survey was then completed to document the location and
general size distribution of the deadfall trees and provide an
indication as to the approximate number that need to be removed, which
is necessary to determine the opinion of probable cost. A photo record
of the areas of concern and typical situations is included in this
project summary.
opinion of probable cost
The Opinion of Probable Cost (OPC) to remove the deadfall trees was
determined based on the number of trees to be removed, their location
and the equipment and time required. Based line cost data was gathered
from various contractors who have completed similar work. This cost
opinion was then completed using the best available data at the time
this application was prepared. Bidding and contracting for this work
has the probability of resulting in either higher or lower costs
depending upon a number of factors including, but not limited to,
economic conditions, time of work, and contractor availability. The OPC
for this project is approximately $430,100 or roughly an average of
$3,162 per deadfall tree.
benefit--cost ratio determination
The development of a benefit to cost ratio to justify the
mitigation funds required a certain amount of generalization and
estimation of present values. First, the risk for ice jams varies from
year to year and is based on a number of climatic factors and the
probability for various stream flows. Since the probability for such an
event exists in any given year it is assumed that flood flows can and
will occur, therefore waiting to mitigate avoidable damages is not an
acceptable option.
The basis for benefits provided by the deadfall tree removal is
measured in two separate ways, which are cumulative. First, is to avoid
further losses in channel conveyance associated with the accumulation
of sediments over, around and downstream from the deadfall trees.
Second, is to avoid the expenditure of public and private resources to
fight an ice jam flood event resulting from this additional sediment
accumulation.
The continued sediment accumulation increases the potential
frequency for ice jam and higher flood events. The cost to remove these
deadfall trees also increases dramatically if they are covered or
entrapped in future sediment deposition. These additional sediments
would have to be removed to access these trees; therefore removal of
these materials is necessary not only to access the trees to prevent
future deposition but to restore the lost channel conveyance. The value
of not having to remove these sediments in the future is deemed a
present value benefit of the removal project. The removal costs are
based on the use of a hydraulic dredge to avoid the placement or
relocation of fill materials within the Missouri River Floodway.
Discharge, disposal and storage of these materials most likely would
occur on the left bank on properties owned by the State of North
Dakota.
The present value benefit associated with the deadfall tree removal
was determined based on the projected cost to hydraulically dredge the
projected accumulated sediments associated with the tree's location
within the river. Utilizing an approximation of the aerial extent and
depth of sediment deposition over, around and downstream from an
average size tree it was determined that from 300 to 400 Cubic Yards of
material would be captured by each. While this could occur in 1 year or
over a period of years the net accumulation was totaled for removal
based on a present day cost per cubic yard. The benefit is provided by
the removal of the deadfall trees before these sediments accumulate.
The present value cost is based on a projection of approximately 125
sites, 350 CY per site, and $17 per cubic yard for sediment removal.
Sediment Removal Benefit--$743,750
A 10-year event is used to define the present value cost to defend
the communities against an ice jam flood, which is a flow rate of
68,500 cfs on the Missouri River below the Heart River confluence.
Estimates of the actual 2009 flood flow vary, but likely ranged from
80,000 cfs to 90,000 cfs. It is projected that currently a major ice
jam during the 10 year flood event could result in similar impacts, or
the expenditure of resources as the 2009 flood. The cost to defend
against an ice jam event flood varies dependent upon its location,
nature, extent and duration. For the purposes of this assessment it is
deemed that the general preparedness and resources necessary to battle
a similar event are a reasonable basis for projecting the present value
cost for the flood hazard. It is not specifically known if the ice jamb
event could result from existing sediment deposition without the
removal project; however, the additional accumulation will measurably
increase the current flood hazard. A current conditions analysis is
unavailable.
Based on contacts with the city of Bismarck, city of Mandan, the
Burleigh and Morton County Emergency Managers, and the North Dakota
National Guard we were able to obtain the following estimated public
costs associated with the 2009 flood event. The figures provided are
for reimbursable expenses only and do not include employee or staff
time, or private property financial impacts.
PUBLIC RESOURCE COST--2009 FLOOD EVENT
------------------------------------------------------------------------
Amount
------------------------------------------------------------------------
City of Bismarck--Tabulation of FEMA Reimbursable Expenses. $464,000
City of Mandan (estimated)................................. 200,000
North Dakota National Guard--Ice Jam Demolition............ 80,000
------------
Total................................................ 744,000
------------------------------------------------------------------------
The private cost to defend against the 2009 event or damages
incurred were not readily available, from the sources contacted, at the
time this application was completed.
Private Costs (Undetermined)--$ Unknown
Both the Public and Private costs are additive utilizing a 10-year
timeframe the probability of a 10 year event occurring within the next
10 years is approximately 39 percent. Therefore, the following is the
projected present value benefit of the project:
Public resource Benefit--$744,000 0.39 = $290,160
BENEFIT--COST SUMMARY
------------------------------------------------------------------------
Amount
------------------------------------------------------------------------
Total Present Value Benefit:
Public Resources Benefit............................ $290,160
Private Resources Benefit........................... ( \1\ )
Sediment Removal Benefit............................ 743,750
---------------
Total............................................. 1,033,910 ===============
Total Present Value Costs:
Projected Deadfall Tree Removal and Disposal........ 430,100
------------------------------------------------------------------------
\1\ Undetermined.
Combined B/C Ratio $1,033,910/$430,100 = 2.40:1
summary notes
The B/C ratio does not include the private benefits associated with
avoidance of damages associated with an ice jam flood event. Inclusion
of this figure would further increase the B/C ratio.
The B/C ratio does not include the lost Federal hydropower revenues
associated with the need to cut releases during an ice jam event or the
restricted flows under the ice due to the existing and future
sediments. These costs were not quantified as part of this evaluation.
The projected costs are based on early projections of time and
materials required to complete the project. Additional evaluation and
design may result in savings once the plans and specifications have
been completed.
acknowledgments of data sources
Dale Frink, PE, North Dakota State Engineer
North Dakota State Water Commission
Burleigh County WRD
Morton County WRD
Lower Heart WRD
City of Bismarck
City of Mandan
Burleigh County Emergency Management
Morton County Emergency Management
Square Butte Dredging, Morton County--Hydraulic Dredging Cost Data
Ron Sando, PE, Engineering Consultant
Adventure Divers, Inc, Minot North Dakota--Construction Cost Data
Corps of Engineers--Bismarck Regulatory Office
USFWS--Threatened and Endangered Species Data
NDGF--Enforcement Division
appendix a--aerial and field reconnaissance photo record
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Mr. Gunsch. This grant application was declined. And the
project was deemed to be snagging and clearing which is
interpreted by maintenance under FEMA's guidelines. That
decision has been appealed and is still under review at this
point in time.
I'll paraphrase a couple other issues.
Restoring and maintaining flood water conveyance in the
Missouri River system through the Bismarck/Mandan area is of
critical importance, as is pointed out by all of us being here
this evening. Since flood protection is the No. 1 priority for
the management of the Missouri River system and the issue of
flood protection for Bismarck/Mandan should be a high priority
as well. The development of mitigation measures whether they
include development controls, dredging, channel modifications,
levees or other measures or combinations thereof, need to have
attention now to reduce and manage the risk for future flood
events.
Another critical issue in the discussion for any flood
control or flood hazard mitigation project is the operation and
maintenance. And the question has to be asked who maintains the
river? While the riverbed is sovereign land owned by the State
of North Dakota, the Federal Government has taken and accepted
control and management of the river system.
As flood protection and sedimentation issues are a function
of that management and maintaining flood conveyance should be a
Federal responsibility. We understand this requires the Federal
Government to establish the necessary authorities to allow the
Corps to participate in that effort. We're also aware of the
many ongoing reviews and studies regarding the Missouri River
including MRRIC, MRERP, MRAPS and others. And while each has
its own commendable effort in their own right, none should
preclude the advancement and development of what hazard
mitigation efforts to protect Burleigh and Morton County and
the communities of Bismarck and Mandan.
A final concern is the completion of the Missouri River
cumulative environmental impact statement as there are those
who are holding up that particular study on the river at this
time.
And if you'd indulge me just a moment, I'd read a statement
from the Water Resource District relative to the Fox Island
area.
``The March 2009 Missouri River ice jam flood event had
significant impact on residents in the Fox Island area located
in South Bismarck. This flood happened very quickly and with
such little notice to the residents who subsequently had very
limited ability and time to prepare or even respond to protect
their properties. During a recent public informational meeting
Fox Island residents were able to provide comments and concerns
to the Burleigh County Water Resource District regarding these
events and we summarized these in four major points.
``Having lived on the river for many years some residents
noted that the Corps did not raise the river level this winter
and again this spring to break up the ice flows as they've seen
in the past. And they question why? Others question why the
Corps is relying on a gauge that is several miles upstream from
Fox Island on which to base the response for ice jam flooding.
Thus, in their opinion the Corps' reaction was delayed. And the
State of North Dakota had to request action to reduce releases
from Garrison Dam.
``There needs to be more attention paid to the
sedimentation issue and ice jam risks as the delta formation is
growing and needs to be addressed. And what impacts are the
proposed developments having on Missouri River flood plain
elevations? And we provided a copy of the power point
presentation that was made by the Water Resource District to
those residents to give you some background as well.
``The Burleigh County Commission, the Burleigh County
Highway Department and the Water Resource District have taken a
proactive approach to the issues that happened. They're looking
at mitigating to the extent possible within reasonable economic
means those issues that happened after the 2009 flood. One
critical problem encountered during the flood was the inability
to access these residential areas because the primary access
roadways were inundated. The county and township are in the
process of implementing several road grade raises to improve
emergency access for such events. And while not providing 100
year access it is a measured, economical approach to the access
issue.
``The Burleigh County Water Resource District has also
formally requested that the city of Bismarck and Burleigh
County revise their current flood plain management ordinance to
require the first floor flood elevations and crawl spaces for
new construction to be placed a minimum of 2 feet above the
base flood elevation which is currently higher than the one
foot requirement.
``In addition a number of local residents have signed a
petition to the Water Resource District to implement flood
control measures to protect them as reasonably practical from
limited ice jam flood events. Again, while this will not
provide 100 year flood protection, there is some ability to
provide additional protection under existing conditions. Even
so residents remain at significant risk for flooding in adverse
impacts from ice jams and high water events still exist.
``Another mitigation measure under consideration is the
development of emergency action and response plan to govern the
actions during the next such event. We understand to some
extent this may require the update of the Burleigh County
Multi-hazard Mitigation Plan to incorporate those future flood
scenarios. While these measures are being implemented it is
requested that the Corps conduct a post flood elevation. This
should include a written report to the Burleigh County, Morton
County and the State of North Dakota on how the flood event
occurred from a river management perspective and what if any,
reservoir control and operation measures might be implemented
to mitigate future risks.''
PREPARED STATEMENT
And that particular statement was submitted and read by
myself for Gailen Narum, the Chairman of the Water Resource
District.
Thank you.
[The statement follows:]
Prepared Statement of Michael Gunsch
Senator Dorgan and subcommittee, thank you for the opportunity to
provide testimony regarding the flooding concerns in the Bismarck-
Mandan area.
My name is Michael Gunsch. I am a resident of Bismarck, and a
registered professional engineer in the State of North Dakota and
principal in the firm of Houston Engineering. Houston Engineering is
currently the district engineer for the Burleigh County Water Resource
District and is an engineering consultant to the Morton County Water
Resource District. My remarks today are presented on behalf of the
BCWRD, MCWRD and the Lower Heart Water Resource District (LHWRD) and
relate primarily to the technical nature of the flooding issues.
In July 2009 Houston Engineering was retained by the BCWRD in
cooperation with the MCWRD and LHWRD to identify alternatives to
mitigate flood hazards associated with the Missouri River. The costs
for this effort are underwritten in part through a cost share grant
from the North Dakota State Engineer. The primary focus is to define
pre-disaster mitigation alternatives that can be implemented to reduce
the existing and projected flood risks for Burleigh and Morton County.
After evaluating the March 2009 ice jam flood event and reviewing prior
studies, the following objectives were developed for further
consideration:
--Sediment and debris removal from within the upper reaches of the
Oahe Delta formation below the Heart River Confluence to
mitigate the impacts and risks associated with ice jam flood
events and future sediment deposition;
--Evaluate the status of potential aggradation and on-going changes
in stream channel conveyance downstream from Bismarck-Mandan
and its impact on the risks associated with ice jam and open
water flood elevations;
--Evaluate the feasibility of alternatives to lower the current Base
Flood Elevation (BFE) to those levels documented in the 1985
Flood Insurance Study (FIS). The focus to be on the reach
between the USGS Bismarck Gage at Missouri River Mile 1314.5
south to approximately Missouri River Mile 1302 (approx. Oahe
Project Boundary). Alternatives shall include, but not be
limited to, dredging, channel improvements, reservoir
operations, and structural measures or a combination thereof;
--Define existing and future land uses within and proposed bank
stabilization measures along the Missouri River Correctional
Facilities property, as necessary, to achieve the objectives
outlined in Item No. 1, Item No. 2 and Item No. 3. There is
nexus between project construction or dredging within and along
the river and the need for access and potential use of adjacent
properties for the placement of dredge materials; and
--Complete an assessment to determine the potential (economic) flood
damages or impacts associated with future increases in the
Missouri River BFE and flood risks in Burleigh and Morton
Counties. This effort includes a GIS based analysis of the
existing and potential flood impact areas.
The tasks and potential costs associated with accomplishing these
objectives, which include local, State and Federal issues, are still
under development.
Concerns regarding the Oahe Delta have been around for many years
with no action taken since 1985 to address the eventuality of what
might occur. The March 2009 ice jam flood event significantly increased
everyone's awareness of the issue and subsequently has raised the level
of concern. The Corps of Engineers (COE) August 1985 study entitled
Oahe-Bismarck Area Studies, Analysis of Missouri River Flood Potential
in the Bismarck, North Dakota Area evaluated various alternatives to
mitigate flood impacts associated with the continuing delta formation.
A copy of this report is provided for reference. These included options
such as dredging, channel cutoffs, bank stabilization, levees, Garrison
operational changes, Oahe operational changes, land acquisition and
floodplain management. The study's conclusion was to change reservoir
operations to minimize releases during critical high discharge periods,
and to recommend communities consider implementing additional criteria
for floodplain development, raise access roadways, and encourage
participation in the National Flood Insurance Program. Given the March
2009 event we have to question if operational changes alone are
adequate to address the ice jam risks.
The 1985 study predicted that the base flood elevations (BFE's) in
the Burleigh and Morton County areas would increase and over time
eventually reaching a projected equilibrium. Unfortunately these
increases and the equilibrium elevations occurred in a 17 year period
between the 1981 and 1998 data sets. These increased BFE's are
reflected in the 1985 and 2005 Flood Insurance Study (FIS)
respectively. There are a number of professionals who agree this is not
the end of the increases that will be experienced, therefore more needs
to be done before the situation deteriorates further, and we are
already 10 years past the last data set.
More recently the COE under section 108--Missouri River Protection
and Improvement Act 2000--title VII enlisted the professional
engineering services of The Louis Berger Group, Inc. to complete a
report entitled Impacts of Siltation of the Missouri River in the State
of North Dakota Summary Report 29, June 2009, [Berger Report]. A copy
of the Berger Report is provided for the record for reference as it
contains significant information and data that documents and justifies
our concerns. The following examples are taken from this report and
copies of these tables are attached to my testimony for direct
reference:
table 2.13--floodplain area comparison
Table 2.13 provides a tabular summary of the expansion of the
special flood hazard areas or floodplain between 1985 and 2005. Based
on this table flooding on the 100-year event during this period within
the Bismarck City limits has increased from 2.7 to 3.6 square miles,
while in Burleigh County it has increased from 28 to 36 square miles.
This represents a 28.6 percent increase or expansion of the floodplain
between the two studies. No data was provided for Morton County.
appendix f--impact of siltation on flood control, table 3.1--flood
elevation comparison
Table 3.1 illustrates the documented increases in the base flood
elevations along the Missouri River system from 1985 to 2005. The
average increase being around 1 foot on the 100 year event in the Fox
Island area south of Bismarck. While development standards within this
special flood hazard area have changed, continuing increases in the
flood elevations presents a significant challenge and unknowns, which
have diminished the value of those efforts. Therefore, more information
is necessary to protect those located within the floodplain and to
adequately protect potential future development.
So the question is this--What can be done?
The response to this is fairly direct and documented in the Berger
Report in the following:
table 7: recommendations for addressing sedimentation impacts along the
missouri river in north dakota, under flooding risks in the bismarck/
mandan area
This table lists the following four Study/Product Items:
--Tradeoff Analysis of Flood Controls (e.g., development restrictions
vs. flow restriction).
--Study impacts of sedimentation of flood risks when Lake Oahe pool
is full.
--Develop strategies for mitigating ice-affected flooding exacerbated
by sediment deposition at the headwaters of Lake Oahe.
--Conduct debris/snag removal in the Heart River confluence area.
This will minimize sediment accumulation in the area and
decrease the likelihood of ice-affected flooding.
The timeframe to complete each of these Project/Study items ranges
from short term, to 3 to 5 years. The total combined costs range from
$2 million to $4.2 million. These Project/Study costs are not inclusive
of all the elements under consideration by the BCWRD, MCWRD and LHWRD.
Therefore, there are additional costs that remain to be identified.
The fourth item on the Project/Study list, to conduct debris/snag
removal (e.g., deadfall trees), is one of immediate concern to reduce
the risk for the recurrence of ice jams south of the Heart River. The
debris remnants from the 2009 flood will become increasingly more
difficult to remove once they are covered by additional river
sediments. A Flood Hazard Mitigation Grant was submitted to the North
Dakota Division of Emergency Management in July 2009 to complete this
mitigation work and had a projected cost of around $430,100. A copy of
the Project Summary and Risk Assessment included in this application is
provided as a reference with this statement. This grant application was
declined the project was deemed to be snagging and clearing which is
interpreted to be maintenance under FEMA's guidelines. This decision
has been appealed and will undergo further consideration.
It should be noted that there are more benefits provided than were
specifically presented in the Project Summary and Risk Assessment as
not all costs were readily available at the time of application. We now
understand the cost to the rural electric power cooperatives alone, due
to the need to purchase replacement power during reduced releases from
Garrison Dam during the ice jam event, was in excess of $2 million. As
additional background the 1985 study noted the loss in ability to
generate hydropower due to sedimentation had an economic loss ranging
from near zero in 1985 to a full annualized loss amount of $500,000, in
1985 dollars, occurring around 2005. This economic loss is directly
related to operational changes caused by a reduction in flow capacity
during the winter associated with sedimentation and ice conditions.
Restoring and maintaining floodwater conveyance in the Missouri
River system through the Bismarck-Mandan area is of critical
importance. Since flood protection is the number one priority for
management of the Missouri River system the issue of flood protection
for Bismarck-Mandan should be a high priority as well. The development
of mitigation measures whether they include development controls,
dredging, channel modifications, levees, other measures, or a
combination thereof need to have attention now to reduce and manage the
risks for future flood events.
Another critical issue for any flood control or flood hazard
mitigation project is operation and maintenance. The question has to be
asked--who maintains the Missouri River? While the riverbed is
sovereign land owned by the State of North Dakota the Federal
Government has taken and accepted control and management of the river
system. As flood protection and sedimentation issues are a function of
that management, maintaining flood conveyance should be a Federal
responsibility. We understand this will require the Federal Government
to establish the necessary authorities to allow the COE to participate
in this effort.
We are aware of the many ongoing reviews and studies regarding the
Missouri River including MRRIC, MRERP, MRAPS and others. While each of
these is a commendable effort in their own right none should preclude
the advancement and development of flood hazard mitigation efforts to
protect Burleigh and Morton County and the communities of Bismarck and
Mandan. A final concern is the completion of the Missouri River
Cumulative Environmental Impact Statement as there are those who are
holding up any project on the river until this is completed.
Thank you for the opportunity to present this information.
TABLE 2.13.--FLOODPLAIN AREA COMPARISON
------------------------------------------------------------------------
Burleigh County Bismarck City Limits
------------------------------------------------------------------------
1985 100-year Floodplain--28 mi\2\........ 1985 100-year Floodplain--
2.7 mi\2\
2005 100-year Floodplain--36 mi\2\........ 2005 100-year Floodplain--
3.6 mi\2\
------------------------------------------------------------------------
mi\2\ = square miles.
In urban areas such as Bismarck and Mandan, flood plain development
restricts the Missouri River's ability to accommodate increases flows
during certain storm events (e.g. river channel has no room to widen
without affecting properties). Aggradation in this area of the river
compounds the problem resulting in an increase risk of flooding and the
loss of property. Potential buyouts due to flooding concerns in the
Bismarck-Mandan area are estimated at over $100 million.\1\ The impact
of flooding is estimated to be greatest between RM 1300 and 1316, i.e.,
in downtown Bismarck and Mandan.\2\ Flooding also occurs outside of
urbanized areas, affecting cropland and causing soil erosion.
---------------------------------------------------------------------------
\1\ Remus, John, Personal Communication, November 2008.
\2\ FEMA. Flood Insurance Study--Burleigh County, North Dakota and
Incorporated Areas. FIS Number 38015CV000A. Federal Emergency
Management Agency, July 2005.
---------------------------------------------------------------------------
Property owners whose property now lies within the expanded flood
plain may also be impacted by a decline property values and increased
insurance cost. Homes, businesses, and agricultural land are among the
types of properties most heavily affected by an increase in the 100-
year flood plain.
FEMA manages the National Flood Insurance Program (NFIP) which
insures buildings and structures against flood damage. As a result of
changes in the Flood Insurance Rate Map, all entities requiring a
mortgage for structures on property within the 100-year floodplain will
be required to purchase insurance under the NFIP. Owners of buildings
must purchase insurance against damages to the structure of the
building itself and also against damages to the contents of any floors
below flood level that would be inundated in the event of a 100-year
flood. Owners may purchase a basic level of coverage or increase
coverage for an additional cost. The cost of the insurance is based on
the area of the building (square feet). The insurance rate per square
foot is dependent on the building's characteristics, on the date of
construction of the building, and on the ``flood zone'' that the
building is located in.
There are four different types of buildings covered under NFIP:
Non-residential; Single-family dwellings; Condominiums; and 2-4 family
dwellings.
TABLE 3.1--FLOOD ELEVATION COMPARISON
--------------------------------------------------------------------------------------------------------------------------------------------------------
Flood Elevations, (feet) NAVD Changes in Flood
------------------------------------------------------ Elevations from 1988 to
Key Milestone River 1988 Flood Data 2005 Flood Data 2005 (feet)
Station --------------------------------------------------------------------------------
50 yr 100 yr 500 yr 50 yr 100 yr 500 yr 50 yr 100 yr 500 yr
--------------------------------------------------------------------------------------------------------------------------------------------------------
Confluence Apple Creek...................................... 1,300.21 1,626.7 1,627.7 1,631.0 1,627.9 1,629.0 1,632.1 1.2 1.3 1.1
Confluence Little Heart River............................... 1,302.22 1,628.3 1,629.3 1,632.8 1,629.6 1,630.7 1,633.8 1.3 1.4 1.0
Confluence Heart River...................................... 1,310.72 1,633.7 1,634.9 1,638.3 1,634.5 1,635.7 1,638.8 0.8 0.9 0.5
Bismarck Expressway......................................... 1,313.41 1,635.1 1,636.3 1,639.8 1,636.0 1,637.3 1,640.4 0.9 1.0 0.6
Memorial Bridge............................................. 1,314.21 1,635.4 1,636.5 1,640.0 1,636.3 1,637.5 1,640.8 0.9 1.0 0.7
Railroad.................................................... 1,314.99 1,635.9 1,637.0 1,640.5 1,637.7 1,637.9 1,641.2 1.8 0.9 0.7
Interstate 94............................................... 1,315.49 1,636.1 1,637.3 1,640.7 1,636.9 1,638.1 1,641.5 0.8 0.9 0.8
City of Bismarck Limits..................................... 1,317.42 1,637.7 1,638.9 1,642.9 1,638.2 1,639.6 1,643.6 0.5 0.7 0.6
Confluence Burnt Creek...................................... 1,319.88 1,638.9 1,640.0 1,643.9 1,639.5 1,640.8 1,644.6 0.6 0.8 0.8
Burleigh County Limits...................................... 1,328.64 1,644.0 1,645.0 1,648.5 1,643.7 1,644.8 1,648.4 -0.3 -0.2 -0.1
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: Elevations are from HEC-2 data and HEC-RAS data from the 1988 and 2005 Flood Insurance Studies, respectively.
TABLE 7.--RECOMMENDATIONS FOR ADDRESSING SEDIMENTATION IMPACTS ALONG THE MISSOURI RIVER IN NORTH DAKOTA
----------------------------------------------------------------------------------------------------------------
Input/Resource/Study/Product Timeline Cost Remarks
----------------------------------------------------------------------------------------------------------------
Flooding Risks in Bismarck/Mandan Area:
Tradeoff Analysis of Flood Controls (e.g. Short term.......... $500,000-$1,000,000. Would require local
development restrictions vs. flow partner
restrictions).
Study impacts of sedimentation on flood Two to three years $500,000-$ 1,000,000 Would require a cost-
risks when Lake Oahe pool is full. to complete. share sponsor
Develop strategies for mitigating ice- Three to five years $500,000-$1,000,000. Would require a cost-
affected flooding exacerbated by sediment to complete. share sponsor.
deposition at the headwaters of Lake Oahe. Detailed
Environmental
Assessment (EA),
may be an EIS
Conduct debris/snag removal in the Heart Short term; Less $100,000-$150,000 Would require a cost-
River confluence area. This will minimize than two years to for design. share sponsor
sediment accumulation in the area and complete. $400,000 to
decrease the likelihood of ice-affected $1,000,000 for
flooding. construction.
Garrison Reach:
Complete cumulative Environmental Impacts Two to three years $1,000,000-$2,000,00 Would require a cost-
Statement (EIS) for Garrison Reach. to complete. 0. share sponsor
Conduct bank stabilization projects....... Short term; Less $300,000-$500,000 Very difficult
than one year to per site. without EIS
complete.
Evaluate potential operational changes of Three to five years $1,000,000-$5,000,00 Controversial; Re-
the Garrison Dam and/or flow to complete. 0. opens master manual
modifications. issues; Possibly
outside the scope
of title VII
Fish and Wildlife:
Study to evaluate the needs of multiple .................... $250,000-$300,000 Would require a cost-
species along the Missouri River. (Two-year study). share sponsor.
Overlap with the
BiOp could be
complicated
Study the life-cycle of the pallid .................... $200,000-$250,000 This is part of the
sturgeon on the Yellowstone River. (Two-year study). Missouri River
Recovery Program
Cultural Resources:
Prepare a research design for cultural Short term; less $200,000-$250,000... Would require a cost-
resources along the Missouri River. than two years. share sponsor
Provide a framework for management and
treatment of cultural resources across
jurisdictions.
Study to access cultural and historical Short term; less $250,000-$500,000... Would require a cost-
resource sites to determine if impacts than two years. share sponsor
are occurring.
----------------------------------------------------------------------------------------------------------------
Senator Dorgan. Mr. Gunsch, thank you very much. We
appreciate your testimony. By the way, you cited the Missouri
River cumulative environmental impact statement. I'm not
familiar with that.
What are you referring to?
Mr. Gunsch. The cumulative environmental impact statement
was being written and evaluated for bank stabilization
facilities. In other words there was an issue where people want
to stabilize their banks along the Missouri River and issued
permits because the environmental groups are saying the
cumulative impact of all those facilities is having an adverse
effect on the river.
Senator Dorgan. Who's conducting that?
Mr. Gunsch. I believe the Corps was doing the original
study.
Senator Dorgan. Colonel Ruch, are you familiar with that?
Colonel Ruch. My familiarity is with the length of bank.
Right now I think they're down to where they can only do a 200
foot section at this time. And I know there is some ongoing
work. But I'll have to give you an update on that.
Senator Dorgan. Alright. Roger indicates it may be a
regulatory function. But we'll check back on that.
Let me try to understand, Mayor Warford, you talked about
heavy spring runoff. Do we know how heavy the spring runoff
was? Is this like once in 50 years? Once in 100 years?
Does anybody know?
Mr. Warford. I certainly don't know. I do know that, you
know, we had 100 inches, within an inch of an all time record
snow last year in the city of Bismarck. So that would lead me
to the conclusion that we had significantly more runoff last
year than we've had in most years.
Senator Dorgan. Colonel, have you studied this?
Colonel Ruch. All it takes on top of the 100 inches we had
is a very rapid meltoff and rainfall on top of that. And that
kind of gives a worse case situation where you get all that
released at one time.
Senator Dorgan. Alright, and that was in addition the ice
jams?
Colonel Ruch. Yes.
Senator Dorgan. Ok.
Mr. Royse, you talked about the title VII program. I want
to ask you and the Colonel where we are on that. Is my
understanding correct that there's been a reconnaissance study
on that and to move to the next stage would require a local
sponsor?
Colonel, is that correct?
Colonel Ruch. It is correct. And Mr. Gunsch did a good job
of recapping his table 7 that he submitted. Basically the
legislation outlined three phases.
The first phase was an assessment which has just been
completed.
The second phase of the plan would identify selection
criteria for the project's implementation process of those
projects he actually discussed.
The third phase would go to construction.
The assessment was a cost-shared study with the Missouri
River Joint Water Board. And it identified these projects that
he listed for task force consideration in the plan and project
phases. The assessment was completed in 2009, but no sponsors
have stepped forward to cost share.
Senator Dorgan. Now you would not move forward unless
there's a local sponsor. And the local sponsor at that next
stage, that's a 50/50 cost-share, is it?
Do you know?
Colonel Ruch. I believe it's a 75/25 cost-share on that.
Senator Dorgan. Is it? Ok.
Colonel Ruch. It's a little different than most.
Senator Dorgan. But in order for you to move to the next
phase you need a local sponsor? Is that your understanding, Mr.
Royse?
Mr. Royse. Senator, that is correct. And the Missouri River
Joint Board was a local sponsor on the study. This is the
study. It is complete.
Senator Dorgan. Is it likely that there will be a local
sponsor for the following step?
Mr. Royse. Well, Senator, I will tell you this. That of the
projects they identified most of the projects appear to be
further studies. And we have a concern about that.
Senator Dorgan. Ok.
Mr. Royse. And so if there are further studies I'm not sure
the Missouri River Joint Board would be a sponsor on that.
Senator Dorgan. Alright. Colonel, if a local sponsor is
required to come up with local money for additional studies, I
assume what Mr. Royse is referring to is that they would like
to see something other than a study. So how do they get to that
point?
Colonel Ruch. We have to go through that next phase and do
this study. Even on the number four that he discussed which was
debris and sag removal from the Heart River, we still have to
do the environmental documentation that you discussed at the
beginning of the testimony to be able to go to construction. So
it's not as simple as going out there and getting the work.
Senator Dorgan. Let me have you describe for us, Colonel,
if you would, what are the authorities that the Corps of
Engineers has available to relate the flooding problems in this
area?
Colonel Ruch. I think we've discussed several, especially
title VII of WRDA 2000. But some of the others that you may be
referring to would be section 205 or section 208. I could give
you a little bit of a detail on them.
Senator Dorgan. Just give us a thumbnail of those two. I'm
generally familiar with them.
Colonel Ruch. Section 205 provides standing authority for
the Corps to study and implement flood damage reduction
projects without specific authorizations for those projects.
Section 205 projects can consist of structural or non-
structural flood risk reduction measures to protect urban areas
including towns and villages.
Feasibility studies investigate. It is cost-shared 50/50
for Federal, non-Federal. And for any cost above the initial
$100,000 in unmatched Federal money, construction is shared at
65/35 as you stated earlier.
This program generally looks at small to moderate sized
projects with construction costs capped at about $7 million.
Senator Dorgan. I would like to ask about the issue of
debris removal, and several have mentioned that tonight. Is
debris removal something that generally would require less
environmental analysis than dredging, for example or larger
flood control projects?
Colonel Ruch. You have to go through the basic steps of an
environmental assessment. So until you actually study and see
what the environmental conflicts would be, I can't really say
that it's simpler. It has to do with the ecosystem you're
involved in.
As you know we're involved in an area that is under the
BiOp. So there are many organizations that we have to satisfy.
Senator Dorgan. I've got a number of questions for other
witnesses as well, but I want to try to understand a bit, if I
can, the discussion about debris. The discussion about silting.
A series of things have been discussed here about what I think
is probably incontrovertible with respect to the condition of
the river that exacerbates flooding.
The question is who's responsible for trying to do
something about that, debris removal or dredging? Is the Corps
responsible?
Colonel Ruch. This area is not within the limits of our
project. So we do not have the ability to go out there without
an additional study. We cannot do it within the operations of
our reservoir because it's not within our reservoir boundaries.
Senator Dorgan. Are there additional necessary authorities
that you need?
Colonel Ruch. No. I believe within title VII of WRDA 2000
and the other authorities we have discussed we could move
forward if we identified a cost share partner.
Senator Dorgan. Ok. What would be the length of the
studies, for example under title VII that you're describing?
Colonel Ruch. A year to 18 months. We believe that it would
be less than 2 years to complete. And that's on table 7 that
was referenced.
Senator Dorgan. Mr. Royse, Mr. Gunsch, you both spoke of
this, I'm trying to understand if there are things that can be
done and the Corps has existing authority, provided it goes
through the steps. How long does it take to get through the
steps to actually do the things that we believe will mitigate
the potential for future flooding?
Colonel Ruch. It was referred to in the 1980s. There was a
study done like this. And granted we are many years later, but
many of these things were discussed back then. And we did not
get a cost share sponsor.
Senator Dorgan. I'm going to come back to that question of
a cost share sponsor because one of the problems that we have
is things don't move forward unless there is a local sponsor.
You know, we can gnash our teeth and wipe our brow and wring
our hands about it, but unless there's a local sponsor, we're
not going to make that kind of progress.
Mayor Warford, you talked about the issue of the ice jams
and reaching out to call in teams from across the country and
so on. Can you give us a bit more information?
What have you learned about that? Perhaps you and Mayor
Helbling, what have you learned about that? I assume that the
issue of ice jams will be with us in the future.
Who do you think should assume responsibility? You talked
about trying to find some mechanism that would identify ice
jams more quickly and the potential damage or danger from them.
So what was it that you learned this spring with respect to ice
jams?
Mr. Warford. Thank you, Senator. The city of Bismarck is
concerned with three things.
No. 1, more adequate warning with regard to the rise of the
water for the Fox Island area and South Bismarck and what we
learned was that essentially there is no real data out there on
ice jams. But our feeling is that there would be more
monitoring of the water flow in the tributaries along with some
devices along the Missouri River that we, as a community, could
at least have more warning than just a few hours that the water
is rising.
You know, we were alerted by the citizens that the water
was rising. And you know, we don't have, you know, any means to
do that.
Our second, you know, point is warnings are our first. The
second is, you know, to have an adequate response once there is
flooding to look at, you know, a study so that we have a
response. And maybe do we need some diking or a temporary
diking plan.
And the third thing the city of Bismarck is concerned with
and what we're talking about with the Corps are solutions. Are
there solutions that can, you know, help mitigate it for the
future?
Senator Dorgan. I was on the eastern side of the State when
I received reports that the consequences of a significant
action with a certain ice jam could have caused massive
flooding in a significant part of Bismarck. What would have
been the worst, disastrous consequences? And how close were you
to that last spring?
Mr. Warford. We think we were pretty close, you know, to
it. So when the ice jam was in place and the Corps ice jam
expert came to Bismarck, really there's not a lot of data out
there on what to do with ice jams. The ice jam experts, they
were talking about salting the ice jam and then talked about
the demolition of it. And the decision was made to bring in the
demolition team.
We were prepared as the city of Bismarck for a worst case
scenario had that, the blasting of the ice jam, not been
successful for a rather significant flooding of Fox Island,
Southport. We even had a contingency plan where we were going
to put a temporary dike all the way down Washington Street to
try to save property and possibly lives, you know, east of
there. So our concern is that without the solutions that are
being talked about with, you know, siltation and a lack of
channelization and the flow of water into the Oahe that we're
going to be faced with this again.
And so, we would like to see, you know, some solutions so
that we're not faced with that worst case catastrophic
scenario. We were very, very concerned. We came very close in
our opinion to, you know, having a major disaster had the
blasting not worked.
Senator Dorgan. How many were evacuated in the Bismarck/
Mandan area?
Mr. Warford. I don't know exactly. I think there were
around 200 in McLaughlin and in----
Female Speaker 1 [off mic]. More than that.
Mr. Warford. More than that, ok. There was more than that.
Senator Dorgan. Alright. Mayor Helbling, your response to
that question?
Mr. Helbling. One of the things the city of Mandan learned
through this experience is some type of computerized monitoring
would be very helpful. One thing that we had a hard time doing
is getting accurate information. And it seemed like Mayor
Warford and I were constantly on the cell phone to each other.
Have you heard anything? You know, what's going on?
And then it was the State. I mean, everybody seemed to be
all over the place. We need some type of computerized
monitoring of the river system, not only the Missouri, but the
Heart River system.
We think there needs to be more emphasis placed on the
Heart River. This is the first time that I can ever remember
where the Heart River went out well before the Missouri River
went out. And I was down there and watching it. And the
tremendous amount of debris that was coming out of the Heart
was just coming over the top of the Missouri and laying and
stacking up. And I don't ever remember seeing that happen.
Usually the Missouri River is open before the Heart opens
up. So there was a tremendous amount of water and debris
flowing down the Heart River. So we think more emphasis needs
to be placed on the Heart River and the debris that's laying in
the Heart River.
Some of the things that we've done, we've had some
debriefing meetings after the flooding. And we're working on
some response times, at what elevation we should do what, you
know, at x. We need to notify these people that there's a
concern. At y, this is what we need to do.
So we've been working on some response times and hard
communications within the county, the city and all of the Water
Districts to see when we have to put specific plans in place.
Senator Dorgan. Alright. Colonel Ruch, has the operation of
the Garrison Dam in any way contributed to the flooding
problems experienced here earlier this year? I guess the follow
up question would be is the Corps looking at any changes to the
operation of the Dam given the experiences this spring?
Colonel Ruch. It's interesting when you look at the
different advice you get on how much water to release in some
of these situations. You know, you'll get advice that you need
to release more to break the ice jams up. You'll get advice
that you need to go in the other direction and turn off the
water, which is what we did last year.
Senator Dorgan. Is that the first time since the Dam was
built that the releases were shut down?
Colonel Ruch. That is the first time ever that the average
daily release has gone below, I believe, 4,100 cubic feet per
second. And it was shut off completely.
Yet, the real dilemma here is you have intakes upstream of
Bismarck. And you need, at about 10,000 cubic feet per second
you can have your intakes in the water. There are two
powerplants and there is a municipal plant as well. When you
cut the water below that then you have to shut down powerplants
at a very cold time of the year.
There is a lot of consultation that goes on there. I'll
give you the book answer here. How has the operation of
Garrison Dam contributed to the flooding problem?
Garrison Reservoir provided significant flood damage
reduction during this year's spring event. Corps preliminary
estimates of actual flood damages in Bismarck are in the range
of $18 million. Damages would have been in excess of $100
million without the Dam in place.
The regulation of Garrison reservoir significantly reduced
the peak stage in the Bismarck area during the spring flooding
event. This peak stage and discharge that occurred during the
event was 16 feet, had an estimated flow of 27,000 cubic feet
per second. Had Garrison Reservoir not been in place the peak
would have been approximately 82,000 cubic feet per second
which corresponds to an open water stage of nearly 20 feet.
It's impossible to determine whether or not the ice jam
would have formed without the reservoirs in place or if those
stages had not formed. As far as looking at operations
afterwards, we continue to monitor. But really the bottom line
is you cannot predict the ice jams.
Senator Dorgan. Sorry?
Colonel Ruch. You cannot predict when an ice jam is going
to occur. We were already dropping our water levels. So we will
continue to monitor and control releases as best we can in
every situation. We don't think there's an overall lesson
learned here that tells us to do something different.
Senator Dorgan. What mechanisms exist to try to detect the
formation of an ice jam? Is there an opportunity in the early
formation of an ice jam to address it as opposed to allowing it
to----
Colonel Ruch. The ice tends to pile up very quickly.
Senator Dorgan. Very quickly.
Colonel Ruch. It's not as if you can get in there. Where
you're talking about measures for dealing with ice jams, there
are permanent structures that are very, very expensive. I doubt
that we could ever get the cost benefit ratio required for
that. There are places that have effective monitoring, early
warning systems.
I have a note and I can't give you a lot of detail about
it, but the State of Nebraska implemented an ice jam reporting
network in 1993. Basically it tied together emergency
management authorities just to keep everybody tied in and
aware.
Senator Dorgan. Do you have the authorities that you need
at the Corps to deal with the Heart River? Mayor Warford
mentioned Apple Creek. Do you have all the authorities you need
in all those areas?
Colonel Ruch. Yes. I believe we do have the authorities
required, if requested under section 205 of title VII.
Senator Dorgan. Let me go back to this question of the
title VII programs, because I understand what you're saying Mr.
Royse that you've provided some funding and now the question
is, is there a local sponsor for the next step. You're saying
the next step is a study.
On the other hand the next step could be a study that
results in debris removal or dredging 18 months from now. Seems
to me that's better than not having the local sponsor and 18
months from now sitting at a table like this saying, you know
what, we don't want to have a study. Because, you know, the
only way that the Corps can get from point A to point C is to
complete point B as well because that's a legal requirement for
them.
So I guess the question I ask is with a pretty complete
understanding that debris removal is probably important here.
The issue of dredging is important. I mean, that's not a new
issue for any of us.
So how do we get to that point of actually getting the
debris removed and the dredging that is required? Do you see,
Mr. Gunsch or Mr. Royse, do you see at some point local
sponsorship for this?
Mr. Gunsch. Senator Dorgan, the, you know, one advantage of
having a joint water board is we are in position to be a local
sponsor and speak on behalf on a number of county water boards.
So it makes it advantageous that we have this board in place.
And so we've been able to step up and be a local sponsor, not
only on title VII, but a few other Corps programs to this area.
But these are expensive cost share procedures. We have to
rely upon the State water commission to provide us funds so we
can become a local cost share. And how many times can we go
back to the State water commission for funds to be a cost share
partner on these programs is an issue.
Senator Dorgan. No, it's unlimited.
The reason I say that is the State engineer is in the back
of the room. I'll invite him to say a word in a moment. He's
going to be testifying tomorrow when I'm holding a hearing
talking about the Hazen/Stanton area and also down in the
Linton area where we had some significant flooding events as
well.
Dale Frink is here. He is the State engineer. Would you
pull a chair up here? As I said, you're going to be testifying
tomorrow, but would you also want to weigh in on the issue of
local sponsorship?
I know this is not putting a collar around your neck. But
it is the case, as Mr. Royse has just indicated the State water
commission plays a significant role in this.
STATEMENT OF DALE FRINK, STATE ENGINEER, NORTH DAKOTA
STATE WATER COMMISSION
Mr. Frink. Well, thank you, Senator. And, you know, in
terms of the local sponsor, we really push to have a local
representative be in charge. We will help fund them, if at all
possible.
But, you know, if you--we don't like to, especially, you
know, like Bismarck and Mandan, you know, they're large
communities and certainly are capable of managing something
like this. But, you know, we do like to have a local sponsor so
that they are in charge and the residents have a State agency
come in and start dictating some things to them.
Senator Dorgan. You see that the dilemma here is that, I
think, there's general understanding in this room that debris
is a problem. Dredging, the lack of dredging is a problem. Both
of which contribute to an event like this when you have very
heavy runoff and an ice jam. It seems to me both the issue of
debris and dredging are something that seems to be significant.
So the question is how do you get to the point of having
both addressed by the Corps?
Mr. Frink. Well, there are really two issues here. One is
funding. And I think that's the easier part.
And I think where Mike and Ken are getting a little, you
know, concerned is that, you know, even if the State and locals
funded it, we still need a permit from the Corps. And you know
that could be a 2 year study. So you get--you've got two people
here talking to contractors about when can we start. And then
we talk to the Corps and say, well, we've got to do a 2 year
study. And to, you know, with the result being a permit at the
end.
So it's, you know, it's kind of a timing thing. But the
funding is probably easier than, you know, getting through the
other type of things.
Senator Dorgan. I still want to try to get to this
understanding. How do you get from point A to point C without
going through point B, if point B is a legal requirement?
Mr. Frink. Right. Well, in terms of a local sponsor, I
guess I would encourage, you know, the two cities and the two
counties to try to come up with a local sponsor. You know, the
joint board is certainly one possibility. I know they don't
have a lot of money, but, you know, the State Water Commission
could provide some money.
And then you'd still have the local control that I think is
really important here.
Senator Dorgan. See how much I'm helping you here?
At least I'm trying. Thanks, please stick around for a
moment.
Let me ask some questions that Mr. Narum submitted. I think
Mr. Gunsch raised them, and we just will put them on the
record.
This from Gailen Narum, having lived on the river for many
years some residents noted that the Corps of Engineers did not
raise the river level since winter and again this spring to
break up the ice flows as they have seen in the past. They'd
like to know why.
Colonel, can you respond to that?
Colonel Ruch. Well, once again by the time these ice jams
formed and the river was coming up I don't believe that
releasing more water is what anybody downstream really wanted
at that point. We look at each one of these events and decide
how to move forward. More water would have piled more ice up.
Senator Dorgan. Is there a strategy the Corps has
inevitably in the spring or the late winter and spring to
release water to break up or in order to prevent jams from
forming?
The implication of this question suggests there's always
been a strategy.
Colonel Ruch. The typical response to fight the stuff is
perhaps to cut it back a little bit. And then once it
stabilizes to release some more water to increase the channel
underneath. You probably won't find that in a manual, but that
is kind of how it is done. But this ice piled up very quickly.
Senator Dorgan. The other question was why is the Corps of
Engineers relying on a gauge several miles upstream from the
Fox Island area on which to base its response to ice jam
flooding? Thus in their opinion the Corps of Engineers'
reaction was delayed and the State of North Dakota requested
action to reduce releases from the Garrison Dam.
Again, that's from the letter from Gailen Narum. Can you
respond to that?
Colonel Ruch. Not to that individual gauge. I will get an
answer and put that into the testimony. But we rely on the
gauges that are out there.
I will get a better answer for you on that.
[The information follows:]
The Corps utilizes all of the USGS gages available on the Missouri
River and tributaries when making reservoir regulation decisions. It is
unlikely that an additional gage a few miles away from the existing
gage would have resulted in any appreciable difference in our response
or in the effects of our response given there is a two-day travel time
from the dam to the Bismarck area. In addition, since ice jams can
occur anywhere along the river it would be infeasible to site a gage or
series of gages to cover all potential ice jam locations.
Mr. Frink. Senator Dorgan, just a couple of things. I think
tomorrow at the hearings and today there's going to be a
commonality that we need a little more measurements along the
river. And those are USGS gauges. And once they're in place and
then they're available on the Internet for everybody to see.
But I think we do need to look at installing some measuring
devices both on the Missouri and the two locations that we're
talking about tomorrow. And I think we are already looking at
that. And I think we can make that happen.
Senator Dorgan. Alright, we'll discuss that further. Some
have, in testimony, mentioned various structures that might be
advisable. I think Mayor Helbling you talked about structures
on the Heart that you might see as advisable.
By the way, I am going to ask about the jetty question in
just a moment. But structures on the Heart, I think Mayor
Warford, you also talked about a potential structure in Apple
Creek, didn't you?
Mr. Warford. Yes. I'd like to maybe just address, you know,
one other issue too with regard. I'm feeling a little target on
my back. I don't know if Mayor Helbling is as well. But you
know the discussion of the local cost share on this.
You know, I'm hearing that the river is on sovereign State
land. And the Corps is in charge of the water. Yet when it
comes down to, you know, mitigating some of the problems
they're looking at Mayor Helbling and me and our local
communities to come up with the cost sharing money. And so, I
hope that, at least my position is, is that, you know, we are
maybe more victims rather than participants. I don't know how
the Mayor feels about that.
But as far as the structures, if you're referring to more
gauges and more information, I would be a strong advocate of
that. And would encourage the Corps to, you know, place gauges
where the water rises so that we can make a direct decision
that water is rising here, that there's an imminent flood
rather than having the gauge way up the river and you know,
having the delay. You know, we're you know, based as local
leaders with, you know, coming up with a response we feel we
would--we need to be notified and warned more quickly so that
we can respond more quickly to the citizen's needs.
Senator Dorgan. My question, though, is I think you talked
about the need to put up a temporary dike down Washington and
so on. I also thought you mentioned the contribution of Apple
Creek to certain flooding activities that could be controlled
with a structure. I thought Mayor Helbling talked about a
potential flood control structure on the Heart. I didn't quite
understand what you meant.
So, whenever you talk about flood control you talk about
the things that can exacerbate flooding issues, the lack of
dredging or debris and so on. Then you talk about the other
issues of putting up structures that would probably control
water. I'm asking the general question: are there structure
questions here that are just tangential or are they central to
any flooding issues?
Mr. Warford. Well, the city of Bismarck feels that they
would be a central issue. You know, I talked about in my
testimony the 2009 flood. But a catastrophic flood with a
scenario where let's say the blasting did not work and the
Apple Creek let loose that there would have been more flooding
in Bismarck. And we put up a temporary dike in the Cottonwood
area. And we're prepared to put up more which could maybe be a
permanent dike.
And we talked about other temporary dikes to mitigate that
sort of doomsday scenario which, you know, could have taken
place. So that's what I was speaking of. We need guidance from
experts that, you know, who claim they have models that can
predict, you know, scenarios that would be greater flooding
than we had in 2009. And, you know, what should we be doing as
a community to respond to that situation?
We'd like to be prepared for any and all situations if we
could.
Senator Dorgan. Mayor.
Mr. Helbling. Senator Dorgan, we have several areas along
the Heart River where we've had massive erosion. And we feel
it's very important to take care of these areas or we're going
to start jeopardizing our Highway 6 Bridge. And then also east
of the city, Sitting Bull Ridge, where the river turns there's
a secondary dike that's in place. And it's eroded all into the
tow of the dike already.
And we feel if we don't get that repaired we're going to
wind up redirecting the channel of the Heart River and causing
massive flooding in the southside of Mandan. So there are two
areas of concern for us.
Senator Dorgan. Can you respond, Colonel Ruch, to the issue
Mayor Helbling has raised about the jetty? Mayor, do you want
to repeat that issue that you had with the Corps?
Mr. Helbling. Well, we have that secondary dike system.
There's a secondary structure. And that that has massive
erosion on it right now.
And that's an area where the Heart River turns. And there's
so much erosion there it's already cored a way through the
structure. And we're very afraid that if we do not repair that
area it's going to change the river channel.
The river is actually trying to change. It's taken out that
levee. And we're very concerned with that area. And need to
have it addressed in some manner.
Colonel Ruch. I will answer that one. But also the one
thing I wanted to point out earlier when we were talking about
gauges upstream and where the gauge should be. You have to
remember that the travel time for water from Garrison down to
Bismarck is 2 days.
So more data is better, but no matter what we do, the
impact is 1\1/2\ to 2 days to when we make a change to what
will be seen down here. On this actual issue, I just heard
about this today. I got up here a little bit early and did a
little touring around the area.
So what I'll promise to do is have somebody take a look at
that and work with your folks and make sure we make a good
assessment of the situation. I'm not even certain that it's a
Federal structure. But we will take a look at that and we will
work directly with you and your people on that.
Senator Dorgan. I don't know if there are people in the
room who are old enough to have been here, in Bismarck and
Mandan, when there was chronic flooding with a rather wild
Missouri River that in the spring would--there's one. Anybody
else? So there's three or four, five people in the room who
remember the days before there was a dam that controlled the
river, before we had a series of stem dams on the Missouri
River and controlled flows.
I wasn't here, but as I recall it was not terribly unusual
to have massive flooding and a huge flood threat that would
come running through these two cities and cause very serious
problems. Then we had the building of this dam and the ability
to somewhat control the Missouri River.
So news of significant flooding threats in the Bismarck/
Mandan region has been pretty unusual. That's why what happened
this spring was something that seemed kind of out of the
ordinary. It's why I asked the original question. What has
caused this?
If not a perfect storm, pretty close to a perfect storm in
the sense a substantial snowfall. I think the key that, Colonel
Ruch, you described was very fast melt that has, you know,
unfortunately over in the Fargo area they had a relatively slow
melt which I think saved them a lot of heartache and damage.
Then the two ice jams which together apparently caused problems
and it's very hard to understand what an ice jam means and how
to deal with it.
So this was a very unusual situation. As I indicated
wouldn't have been so unusual 70 years ago, perhaps or 60 years
ago, but it certainly is now.
What I'd like to do for the next 15 minutes or so would be
to invite some in the audience who wish to contribute to do so.
If you have questions for the witnesses I'd be happy to
entertain those as well. If you would stand up and state your
name before asking the question I'd be happy to entertain
questions for about 15 minutes.
Yes, ma'am?
Ms. Berger. My name is Rosemary Berger. I reside at 2826
Woodland Place which is down on Fox Island. My family was one
of five that was rescued by a boat in the spring to get out.
We had water over our mailboxes when they came by boat to
get my family and my neighbors. I want to know. You're saying
that the Corps does not have some kind of a mean. But I've been
told many times that they've raised the river after the first
freeze so that water, the ice pushes up. It breaks that ice.
This is the question that the Fox Island people are asking.
Why wasn't it raised after that first freeze? This ice that we
had this winter because of the cold winter we had and the
amount of snow and rain, whatever we had, was extremely thick.
It was never raised like it normally is.
You're saying this is in the spring that you didn't raise
it. No, we're talking after the first freeze. This is the
question that we have been asking. You did not answer it to
that, if that.
Senator Dorgan. Alright, Colonel, would you respond to
that?
Colonel Ruch. I'll take you through a history of release.
And minimum, once again, minimum release for intake and for the
power plant is 10,000 cubic feet per second.
Again we were coming out of drought conditions still
conserving water. On March 1, Garrison releases were lowered
from the winter release which is 16,000 cfs which is more upper
level to 11,000 cfs in preparation for the expected snow pack
melt in North Dakota between Garrison and Oahe.
The 11,000 cfs release rate was considered the minimum
necessary to support the downstream intake. On the 23rd of
March the river stage at the Bismarck began rising
significantly. The Garrison, the releases were reduced from
11,000 cfs to 6,000 cfs since the downstream tributaries,
particularly the Knife River were getting enough added flow but
continued to support the intakes.
On the 24th we dropped 4,000 cfs and Bismarck continued to
rise, so later that day the decision was made to go to zero.
During the period when the releases were cut to zero we did
shut down power plants and we did take a municipal water intake
out of service.
So we were up at 16,000 cfs. And once again coming out of
drought conditions we were within the acceptable range. I don't
know the actual numbers and whether that's a good answer. But
that's how we were releasing. And we dropped to 11,000 cfs on
March 1.
Ms. Berger. Ok. This last winter was a high measured amount
of snowfall. We never had our January thaw, ok? It was always
in North Dakota have had some kind of January thaw.
So when we talk about this record snowfall. We were short
by one inch. But any other time we would have had some kind of
a thaw during the year. We never had that.
But you're still talking about March. I'm talking something
that would have happened a year ago, when we had our first
blizzard. We got into a freeze situation back maybe, November,
December. Usually that river would rise and that didn't happen.
The year prior to this we had a substantial amount of rain
that came from Montana. Montana had record amounts of snow. And
I sat at your meeting that you had here a couple of months ago.
And everybody at that meeting was praising the Corps of
Engineers for raising the Lake Sacajawea.
Well, you know what, I was angry at that meeting because I
am one of these people that was affected. And you guys didn't
do anything to raise Sacajawea. That was Montana that did it.
That was God that did it. It wasn't you. Ok?
So Sacajawea was raising.
Senator Dorgan. Let me just make another point, however. We
have been through a lengthy drought in which the main stem
reservoirs have been largely depleted. Now in the last 2 years
or so more water has come in.
It doesn't have anything to do with the Corps. It has to do
with snow pack in the Rocky Mountains.
Ms. Berger. Right.
Senator Dorgan. That additional water has come in, and
because the reservoirs have been so depleted they have not
wanted to maximize the releases. That is what they have wanted
to do is to restore additional water in those reservoirs. So
they have not, as additional water has come in, increased
releases just because they're trying to make up what they
should have conserved previously.
Ms. Berger. I'm not asking them to increase. I'm just
asking them why didn't they do what they had done on any normal
year. They would have raised that, any normal year, to allow
that water, that ice to break up so that the water could go
underneath it.
Senator Dorgan. I think you're asking a question that I had
asked the Colonel, and I think he answered it already. Is there
a strategy, in terms of the management of the river flow that
beginning early in a winter is designed to address the issue of
ice?
I've not ever heard of that, and you're saying that that
strategy does not exist?
Colonel Ruch. It does not relate to that day. Once you get
ice on the river then in the beginning you don't release quite
as much. Then you increase your releases to increase the
channeling.
In this case I think you hit on it very well because we
have less of it, but there was more water, like you said
before. It might not have been 20,000 cfs like years before. It
was up at 16,000 cfs because that is what we could afford to do
based on our annual operating plan to get the reservoirs right.
Senator Dorgan. But that had nothing to do with what was
happening this winter. That had to do with trying to refill a
reservoir that had been depleted. Let me suggest something to
you, ma'am.
What I'd like the Colonel to do is to provide us with 5
years of releases/discharge by month for the past 5 years.
Let's all take a look at that and try to understand what was
done by the Corps.
[The information follows:]
GARRISON DAM--AVERAGE DAILY RELEASE FOR MONTH (1,000 CUBIC FEET PER
SECOND)
------------------------------------------------------------------------
Month 2004 2005 2006 2007 2008 2009
------------------------------------------------------------------------
January....................... 19.2 15.4 17.8 15.9 15.0 15.7
February...................... 23.1 13.0 15.5 15.8 15.3 16.1
March......................... 16.7 12.1 14.5 14.8 12.8 10.0
April......................... 16.9 17.4 13.8 13.5 12.5 9.0
May........................... 15.8 16.5 15.3 13.3 12.9 13.3
June.......................... 18.0 15.0 19.8 16.0 14.3 15.9
July.......................... 17.9 15.2 20.6 15.9 13.6 15.7
August........................ 17.2 15.5 22.0 16.0 13.9 16.0
September..................... 15.0 14.1 18.1 11.6 12.6 14.8
October....................... 11.5 12.6 12.1 10.8 11.0 12.6
November...................... 12.7 13.4 13.1 10.8 11.0 12.8
December...................... 15.2 15.4 15.3 14.9 13.9 .....
------------------------------------------------------------------------
Ms. Berger. Ok.
Senator Dorgan. And I appreciate your coming and raising
those questions.
Do others wish to ask questions?
Ma'am, if you would give me your name and address following
the meeting because I will provide that for you when the Corps
gets it to me.
Ms. Berger. Ok.
Senator Dorgan. Alright. Sir.
Dr. Kronberg. I'm Dr. Scott Kronberg, a range scientist out
at the Northern Great Plains Research Lab. But I like trees
too, so I elected to live on Fox Island.
And one concern I have after listening to the comments was
assuming a study is done to allow for the removal of these
Cottonwood trees and other debris and possibly dredged, how
long is that study good for? I mean, can we remove debris for 5
years, 1 year, 10 years?
Senator Dorgan. Colonel?
Dr. Kronberg. It would be a bummer if we spent 2 years
doing a study and get to remove debris for a year or dredge for
a year.
Colonel Ruch. Your question is a great one because that's
why we really have to do the study because all of these
authorities allow us to go into a project and it is dredging.
It doesn't allow for follow on maintenance dredging. So you
really have to make sure you're solving a problem.
Typically sedimentation occurs at a place in the river
reach for a reason. So just dredging it out doesn't mean it
stays open. We really have to make sure that we're addressing
the bigger problem and not just getting to a quick solution
that might last 6 months, might last a year.
It's a good question.
Senator Dorgan. You know, the one thing I'm understanding
from tonight's discussion is that this is not a question of
whether there needs to be action to deal with debris and
siltation in this river. The question is how do we get that
done. Right?
Most of us understand even if we never run into this
problem again with the ice jams and the perfect storm of
massive snowfall, we've still got a problem with debris and
siltation that ought to be taken care of. There is the point
that's raised that well, the river bottom belongs to the State
and the management of the water belongs to the Federal
Government and then the consequences of the problems are
inherited by those who live in those areas.
So somehow we need to get again, from point A to point C so
that at point C we address this issue, siltation and debris.
Then the other questions would be developed from whether it's a
title VII program or other program. Are there other devices,
structures or other things necessary to try to provide added
protection?
Would local government want that to happen and initiate
that as a plan? Because the Corps won't come here and say here
are the six things that you should have. Largely, it goes the
other way. The local government, through a study says here's
what we think we need, and then you develop this criteria.
Is there a Federal interest? Does it meet the cost benefit
and so on? But you've asked a very important question. You
don't want to go 18 months down the road, finish a study, only
to decide that there's a very brief period in which you can do
half the job. That doesn't make any sense.
Dr. Kronberg. Right.
Senator Dorgan. Mr. Gunsch?
Mr. Gunsch. Senator, if I could address kind of the
question relative to the debris removal. I agree from the
standpoint and having discussed with the Fish and Wildlife
Service and Game and Fish in the preparation of the flood
hazard mitigation grant that this particular event was very
unusual in the amount of debris and stuff that came out of the
Heart River. The number of very large Cottonwoods, you know, 4
foot in diameter in some cases that were put down there.
Is this going to happen again? It certainly could. But the
debris removal, as we saw it from the three water resource
districts, this is probably a onetime thing that we shouldn't
have to do for a long time again. As far as the dredging,
that's a larger perspective. And it may need to be done on a
regular basis as was pointed out in the 1985 study.
But again, as far as even the debris removal, there was
discussion of even in the Flood Hazard Mitigation Grant as a
75/25 that the 25 percent cost share needed to come up with.
And they were willing to consider that opportunity if they
could move forward. But again, the permitting side of that has
to be stepped through.
Senator Dorgan. Alright. Yes, sir?
Dr. Hughes. My name is Jim Hughes, Dr. Jim Hughes. I've
lived on the river, south of the ice jam in the Oahe bend area
at the bottom of South 12, that area, since 1981. And I e-
mailed your office the morning before the water began to rise.
You could look back and see when that was.
But I looked out the window and saw a 5 foot rise in the
river, nothing on the news below the ice jam. I guess the point
I want to make is that whatever was happening north when the
river was blown, when the charges went off. I was downstream of
that.
The water was in my yard at the same level it was in 1997
when the river was running at 60,000 cfs. So I think what
decompressed the river, ultimately was the river overtopping
the oxbow that is just south of Bismarck/Mandan. And I think
the 1988 flood plan from the Corps of Engineers did include an
idea of having kind of a decompression channel that would
take--that would go across that oxbow.
I mean it seems to me that you can't prepare for the amount
of silt that's going to arise and all of that. You have to
somehow have a plan that allows for decompression to occur in
an unnatural way or natural way. When you look at Google maps,
Google sky, Google history, you can see where Sibley Island was
in the past in the whole area to the west of us is underwater.
I mean, Sibley Island apparently is an island because it was an
island at a particular time of year.
But the normal decompression or normal--it's a quantitative
change that happens and how the river is working when it
reaches a certain level that overtops that oxbow south of
Bismarck/Mandan.
Senator Dorgan. Thank you very much. Other observations or
questions? Alright.
What I would like to do is first of all I want to be
helpful. I mean I'm chairman of the committee that funds the
Corps of Engineers. I can't create miracles, but I certainly
can be helpful.
I want to be helpful in areas across the country and in
areas where we've got, Lord knows, we've got a lot of water
issues all across the United States that we're working on. In
this State, though, we had plenty of water issues to consume
our time that were significant and potentially dangerous in
many areas of the State. One of those areas was Bismarck.
When I ask about Bismarck/Mandan, when I ask about the
potential catastrophic result, had everything gone badly my
assumption is there would have been massive damage, massive
evacuation. This would have had a very, very significant impact
on a region of our State. So coming that close to that
significant an impact, the question is what can be done to try
to reduce the possibilities of that happening again?
I think from this discussion there are some obvious
answers. There are also some which are not yet obvious that may
come from some further inquiry. There will need to be, it seems
to me, further discussions with the local government officials,
the mayors, the State water commission and the Corps of
Engineers so that we can understand what use of the authorities
the Corps now has, and what could move us in the direction of
getting these issues solved. Also, what additional authorities
does the Corps need that I might be able to provide if they
need additional authorities to address these issues.
I'm pledged to do that, but I don't necessarily know what
that might be as a result of this hearing. I just wanted to
hold the hearing to try to understand, as best I can, what
really needs to be done.
I think much of that is still going to rely on you, with
the Corps, to tell us what we can do to be helpful. I think
that there is a common determination. Nobody wants to go
through this again.
I think one thing I have learned is that there clearly
needs to be more monitoring. That is a U.S. Geological Survey
issue. We'll work with them to see that we do that.
I think the woman at the back of the room and the doctor
talked about trying to understand what the river is doing. Well
the more monitoring you have, the more information you're going
to have. With computer technology these days and the Internet,
you have access, real time access, by everybody to that
information which I think could be helpful.
Colonel, would you wish to make any additional
contributions tonight?
Colonel Ruch. Just once again to thank you, Senator, for
bringing us out here and letting us get a perspective from the
people who live in this city. And these are good partners I'm
sitting with up here. And we have met with many of their staff
since the flooding and we will continue to do so to move
forward.
Thank you.
Senator Dorgan. Ok. Mayors, did you want to make any
additional comment?
Mr. Warford. Thank you again, Senator, for the hearing. And
I'll go back to my original talking points.
We want in the city of Bismarck, more warning.
We would like to partner with whomever to get a more
adequate response. We could up our game there.
And finally, long term solutions to the river are of strong
concern to us.
But thank you for the hearing.
Mr. Helbling. I'd also like to thank you for the hearing. I
would like to thank the Corps that one of those water intake
structures that the Colonel was talking about was the city of
Mandan's. And the city of Mandan shares that structure with
Tesoro Refinery.
And the Corps did work very well with the city of Mandan.
How long? How much water supply do you have? When do we need to
get more flows in there? How long can we cut it off?
So I realize it was an unusual event. But I think under the
circumstances everybody did work phenomenally together. Sure we
can all do better, but I think we learned a great deal from
this. And I think if we all work together there are good
solutions on the table.
Thank you very much.
Senator Dorgan. Anyone else, any final comments?
Mr. Royse. Senator, I would just say I'm pleased that
you're able to focus on the problem of cost shares as quickly
as you did because that becomes a central problem we have.
Trying to be a cost share partner, when we cannot control the
costs or the time of the project, is a problem.
The second thing I would like to say is I think the
opportunity that we may have to influence how this management
of the river is going to be performed through the MRAPS study
is going to be important. And I'm hoping that the Corps will
involve local and State officials in the process of some real
formal processes, rather than just stakeholders meetings or
task force meetings. But some process, however, has had real
input from State and local officials on this process.
We see this process through MRAPS as not only solving maybe
a flooding issue, but balancing the benefits of that river
system through the upper and lower basin States. Thank you.
Senator Dorgan. Thank you very much, Mr. Royse.
Mr. Gunsch. Thank you very much, Senator, for providing the
opportunity for everybody to communicate in this form. I think
it's advantageous from the water resource districts perspective
to bring these things to the table and have the opportunity for
the Corps to hear them. And I guess everybody always looks
forward to working toward a solution.
And with that I just want to thank you for the opportunity.
Senator Dorgan. Dale, if you have any comments? Thank you
for being here. I know I'll be seeing you tomorrow morning as
well.
Mr. Frink. Well, thank you. And I'd just like to say that,
you know, we do work together very closely. And we work very
hard at this.
This was rather an unusual event. And it's one that hasn't
happened in over years. And we learned some things.
The Colonel mentioned the 10,000 cfs for example, labeled
for the power plants. It used to be 8,000 cfs. But what is
happening between Garrison and Price is the river is getting
deeper. And that sediment is being deposited down here by
Bismarck. And that's causing you a problem.
So the river is getting deeper up in that end. And that's
why they ran into more problems that we realized they would.
And so we learned something there.
And we've learned a lot of things in some other areas. So,
you know, hopefully next time we'll be able to do it a little
better. But it is a learning process.
Even, you know, on Washington Street this gate was put in
in 1967. It's the first time we used it. So you know you use
things that infrequently, you know there is a learning curve
involved here.
So, ok, thank you very much.
Senator Dorgan. Thank you. You mentioned the authorizing
purposes study. When I drafted that and put that in the bill it
was very controversial, as you can imagine. One State in
particular downstream is having an epileptic seizure.
But at any rate, it's the right thing to do and an
important thing to do. We have waited for longer than I have
patience to, and finally we're going to drive through this and
get it done.
I'm going to ask Justin Schardin, who works with me on
water issues, to work with the two cities and the water
districts and the Corps to see, on this specific set of issues,
what more we can do, what you want us to do, and what you want
to do for yourselves.
Roger Cockrell and I will work on the subcommittee to
evaluate what is possible to do in our subcommittee work
beginning now in January.
CONCLUSION OF HEARING
I want to thank all of you for being here. As I indicated
tomorrow morning we're going to have a hearing dealing with the
Beulah/Stanton/Hazen flooding issue. Then one dealing with the
Linton area, just to try to get a sense of what happened there,
and what might be necessary to try to mitigate that in the
future.
This hearing is recessed.
[Whereupon, at 8:57 p.m., Wednesday, November 11, the
hearing was concluded, and the subcommittee was recessed, to
reconvene subject to the call of the Chair.]
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