[Federal Register Volume 89, Number 132 (Wednesday, July 10, 2024)]
[Proposed Rules]
[Pages 56693-56714]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-14761]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R08-OAR-2023-0495; FRL-12052-01-R8]


Air Plan Partial Approval and Partial Disapproval; North Dakota; 
Regional Haze State Implementation Plan for the Second Implementation 
Period

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
partially approve and partially disapprove the regional haze state 
implementation plan (SIP) revision submitted by the State of North 
Dakota on August 11, 2022 (North Dakota's 2022 SIP submission), as 
satisfying applicable requirements under the Clean Air Act (CAA) and 
the EPA's Regional Haze Rule (RHR) for the program's second 
implementation period. North Dakota's 2022 SIP submission addresses the 
requirement

[[Page 56694]]

that states revise their long-term strategies every implementation 
period to make reasonable progress towards the national goal of 
preventing any future, and remedying any existing, anthropogenic 
impairment of visibility, including regional haze, in mandatory Class I 
Federal areas. North Dakota's 2022 SIP submission also addresses other 
applicable requirements for the second implementation period of the 
regional haze program. The EPA is taking this action pursuant to the 
CAA.

DATES: Written comments must be received on or before August 9, 2024.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R08-
OAR-2023-0495, to the Federal Rulemaking Portal: https://www.regulations.gov. Follow the online instructions for submitting 
comments. Once submitted, comments cannot be edited or removed from 
https://www.regulations.gov. The EPA may publish any comment received 
to its public docket. Do not submit electronically any information you 
consider to be Confidential Business Information (CBI) or other 
information whose disclosure is restricted by statute. Multimedia 
submissions (audio, video, etc.) must be accompanied by a written 
comment. The written comment is considered the official comment and 
should include discussion of all points you wish to make. The EPA will 
generally not consider comments or comment contents located outside of 
the primary submission (i.e., on the web, cloud, or other file sharing 
system). For additional submission methods, the full public comment 
policy of the EPA, information about CBI or multimedia submissions, and 
general guidance on making effective comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets.
    Docket: All documents in the docket are listed in the https://www.regulations.gov index. Although listed in the index, some 
information is not publicly available, e.g., CBI or other information 
whose disclosure is restricted by statute. Certain other material, such 
as copyrighted material, will be publicly available only in hard copy. 
Publicly available docket materials are available electronically in 
https://www.regulations.gov. Please email or call the person listed in 
the FOR FURTHER INFORMATION CONTACT section if you need to make 
alternative arrangements for access to the docket.

FOR FURTHER INFORMATION CONTACT: Holly DeJong, Air and Radiation 
Division, EPA, Region 8, Mailcode 8ARD-IO, 1595 Wynkoop Street, Denver, 
Colorado 80202-1129, telephone number: (303) 312-6241, email address: 
[email protected]; or Joe Stein, Air and Radiation Division, EPA, 
Region 8, Mailcode 8ARD-IO, 1595 Wynkoop Street, Denver, Colorado 
80202-1129, telephone number: (303) 312-7078, email address: 
[email protected].

SUPPLEMENTARY INFORMATION: Throughout this document wherever ``we,'' 
``us,'' or ``our'' is used, we mean the EPA.

Table of Contents

I. What action is the EPA proposing?
II. Background
    A. History of the Regional Haze Program
    B. Roles of Agencies in Addressing Regional Haze
    C. North Dakota's First Implementation Period SIP Submissions
    D. North Dakota's Second Implementation Period SIP Submission
III. Requirements for Regional Haze Plans for the Second 
Implementation Period
    A. Identification of Class I Areas
    B. Calculations of Baseline, Current, and Natural Visibility 
Conditions; Progress to Date; and the Uniform Rate of Progress
    C. Long-Term Strategy for Regional Haze
    D. Reasonable Progress Goals
    E. Monitoring Strategy and Other State Implementation Plan 
Requirements
    F. Requirements for Periodic Reports Describing Progress Towards 
the Reasonable Progress Goals
    G. Requirements for Federal Land Manager Coordination
IV. The EPA's Evaluation of North Dakota's Regional Haze Submission 
for the Second Implementation Period
    A. Calculations of Baseline, Current, and Natural Visibility 
Conditions; Progress to Date; and the Uniform Rate of Progress Under 
40 CFR 51.308(f)(1)
    B. North Dakota's Long-Term Strategy Under CAA 169A and 40 CFR 
51.308(f)(2)
    1. North Dakota's Long-Term Strategy Under CAA 169A and 40 CFR 
51.308(f)(2)(i)
    a. Reliance on Non-Statutory Considerations To Reject Reasonable 
Controls at Coyote Station and Antelope Valley
    i. North Dakota Unreasonably Rejected Controls Based on 
Visibility Modeling
    (a) Modeling Showing No ``Significant'' Change in Visibility Is 
Not a Sufficient Basis To Reject Controls Under CAA 169A and 40 CFR 
51.308(f)(2)(i)
    (b) North Dakota Failed To Consider Visibility Impacts at Out-
of-State Class I Areas
    ii. Projections That North Dakota Class I Areas Will Meet the 
Adjusted Uniform Rate of Progress Is Not a Sufficient Basis To 
Reject Controls Under 40 CFR 51.308(f)(2)(i)
    b. Failure To Consider the Four Factors at Coal Creek and 
Unreasonable Rejection of Controls at Coal Creek and Leland Olds
    2. Other Long-Term Strategy Requirements Under 40 CFR 
51.308(f)(2)(ii)-(iv)
    C. Reasonable Progress Goals
    D. Reasonably Attributable Visibility Impairment (RAVI)
    E. Monitoring Strategy and Other Implementation Plan 
Requirements
    F. Requirements for Periodic Reports Describing Progress Towards 
the Reasonable Progress Goals
    G. Requirements for Federal Land Manager Coordination
V. Proposed Action
VI. Environmental Justice
VII. Statutory and Executive Order Reviews

I. What action is the EPA proposing?

    On August 11, 2022, the North Dakota Department of Environmental 
Quality submitted a revision to its SIP to address regional haze for 
the second implementation period. North Dakota made this SIP submission 
to satisfy the requirements of the CAA's regional haze program under 
CAA sections 169A and 169B and 40 CFR 51.308(f). The EPA is proposing 
to approve the portions of North Dakota's 2022 SIP submission relating 
to 40 CFR 51.308(f)(1): calculations of baseline, current, and natural 
visibility conditions, progress to date, and the uniform rate of 
progress; 40 CFR 51.308(f)(4): reasonably attributable visibility 
impairment; 40 CFR 51.308(f)(5) and 40 CFR 51.308(g): progress report 
requirements; and 40 CFR 51.308(f)(6): monitoring strategy and other 
implementation plan requirements. The EPA is proposing to disapprove 
the portions of North Dakota's 2022 SIP submission relating to CAA 169A 
and 40 CFR 51.308(f)(2): long-term strategy; 40 CFR 51.308(f)(3): 
reasonable progress goals; and 40 CFR 51.308(i): FLM consultation. 
Consistent with section 110(k)(3) of the CAA, the EPA may partially 
approve portions of a submittal if those elements meet all applicable 
requirements and may disapprove the remainder so long as the elements 
are fully separable.\1\
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    \1\ See CAA section 110(k)(3) and July 9, 1992 EPA memorandum 
titled ``Processing of State Implementation Plan (SIP) Submittals'' 
from John Calcagni, at https://www.epa.gov/sites/default/files/2015-07/documents/procsip.pdf.
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II. Background

A. History of the Regional Haze Program

    In the 1977 CAA Amendments, Congress created a program for 
protecting visibility in the nation's mandatory Class I Federal areas, 
which include certain national parks and wilderness areas.\2\ CAA 169A. 
The CAA

[[Page 56695]]

establishes as a national goal the ``prevention of any future, and the 
remedying of any existing, impairment of visibility in mandatory Class 
I Federal areas which impairment results from manmade air pollution.'' 
CAA 169A(a)(1). The CAA further directs the EPA to promulgate 
regulations to assure reasonable progress toward meeting this national 
goal. CAA 169A(a)(4). On December 2, 1980, the EPA promulgated 
regulations to address visibility impairment in mandatory Class I 
Federal areas (hereinafter referred to as ``Class I areas'') that is 
``reasonably attributable'' to a single source or small group of 
sources. (45 FR 80084, December 2, 1980). These regulations, codified 
at 40 CFR 51.300 through 51.307, represented the first phase of the 
EPA's efforts to address visibility impairment. In 1990, Congress added 
section 169B to the CAA to further address visibility impairment, 
specifically, impairment from regional haze. CAA 169B. The EPA 
promulgated the Regional Haze Rule (RHR), codified at 40 CFR 51.308,\3\ 
on July 1, 1999. (64 FR 35714, July 1, 1999). On January 10, 2017, the 
EPA promulgated additional regulations that address visibility 
impairment for the second and subsequent implementation periods (82 FR 
3078, January 10, 2017). These regional haze regulations are a central 
component of the EPA's comprehensive visibility protection program for 
Class I areas.
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    \2\ Areas statutorily designated as mandatory Class I Federal 
areas consist of national parks exceeding 6,000 acres, wilderness 
areas and national memorial parks exceeding 5,000 acres, and all 
international parks that were in existence on August 7, 1977. CAA 
162(a). There are 156 mandatory Class I areas. The list of areas to 
which the requirements of the visibility protection program apply is 
in 40 CFR part 81, subpart D.
    \3\ In addition to the generally applicable regional haze 
provisions at 40 CFR 51.308, the EPA also promulgated regulations 
specific to addressing regional haze visibility impairment in Class 
I areas on the Colorado Plateau at 40 CFR 51.309. The latter 
regulations are applicable only for specific jurisdictions' regional 
haze plans submitted no later than December 17, 2007, and thus are 
not relevant here.
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    Regional haze is visibility impairment that is produced by a 
multitude of anthropogenic sources and activities that are located 
across a broad geographic area and that emit pollutants that impair 
visibility. Visibility impairing pollutants include fine and coarse 
particulate matter (PM) (e.g., sulfates, nitrates, organic carbon, 
elemental carbon, and soil dust) and their precursors (e.g., sulfur 
dioxide (SO2), nitrogen oxides (NOX), and, in 
some cases, volatile organic compounds (VOC) and ammonia 
(NH3)). Fine particle precursors react in the atmosphere to 
form fine particulate matter (PM2.5), which impairs 
visibility by scattering and absorbing light. Visibility impairment 
reduces the perception of clarity and color, as well as visible 
distance.\4\
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    \4\ There are several ways to measure the amount of visibility 
impairment, i.e., haze. One such measurement is the deciview, which 
is the principal metric used by the RHR. Under many circumstances, a 
change in one deciview will be perceived by the human eye to be the 
same on both clear and hazy days. The deciview is unitless. It is 
proportional to the logarithm of the atmospheric extinction of 
light, which is the perceived dimming of light due to its being 
scattered and absorbed as it passes through the atmosphere. 
Atmospheric light extinction (b\ext\) is a metric used for 
expressing visibility and is measured in inverse megameters 
(Mm-1). The EPA's Guidance on Regional Haze State 
Implementation Plans for the Second Implementation Period (``2019 
Guidance'') offers the flexibility for the use of light extinction 
in certain cases. Light extinction can be simpler to use in 
calculations than deciviews, since it is not a logarithmic function. 
See, e.g., 2019 Guidance at 16, 19, https://www.epa.gov/visibility/guidance-regional-haze-state-implementation-plans-second-implementation-period, The EPA Office of Air Quality Planning and 
Standards, Research Triangle Park (August 20, 2019). The formula for 
the deciview is 10 ln (bext)/10 Mm-1). 40 CFR 51.301.
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    To address regional haze visibility impairment, the 1999 RHR 
established an iterative planning process that requires both states in 
which Class I areas are located and states ``the emissions from which 
may reasonably be anticipated to cause or contribute to any impairment 
of visibility'' in a Class I area to periodically submit SIP revisions 
to address such impairment. CAA 169A(b)(2); \5\ see also 40 CFR 
51.308(b), (f) (establishing submission dates for iterative regional 
haze SIP revisions); (64 FR at 35768, July 1, 1999). Under the CAA, 
each SIP submission must contain ``a long-term (ten to fifteen years) 
strategy for making reasonable progress toward meeting the national 
goal,'' CAA 169A(b)(2)(B); the initial round of SIP submissions also 
had to address the statutory requirement that certain older, larger 
sources of visibility impairing pollutants install and operate the best 
available retrofit technology (BART). CAA 169A(b)(2)(A); 40 CFR 
51.308(d), (e). States' first regional haze SIPs were due by December 
17, 2007, 40 CFR 51.308(b), with subsequent SIP submissions containing 
updated long-term strategies originally due July 31, 2018, and every 
ten years thereafter. (64 FR at 35768, July 1, 1999). The EPA 
established in the 1999 RHR that all states either have Class I areas 
within their borders or ``contain sources whose emissions are 
reasonably anticipated to contribute to regional haze in a Class I 
area''; therefore, all states must submit regional haze SIPs.\6\ Id. at 
35721.
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    \5\ The RHR expresses the statutory requirement for states to 
submit plans addressing out-of-state Class I areas by providing that 
states must address visibility impairment ``in each mandatory Class 
I Federal area located outside the State that may be affected by 
emissions from within the State.'' 40 CFR 51.308(d), (f).
    \6\ In addition to each of the fifty states, the EPA also 
concluded that the Virgin Islands and District of Columbia must also 
submit regional haze SIPs because they either contain a Class I area 
or contain sources whose emissions are reasonably anticipated to 
contribute regional haze in a Class I area. See 40 CFR 51.300(b), 
(d)(3).
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    Much of the focus in the first implementation period of the 
regional haze program, which ran from 2007 through 2018, was on 
satisfying states' BART obligations. First implementation period SIPs 
were additionally required to contain long-term strategies for making 
reasonable progress toward the national visibility goal, of which BART 
is one component. The core required elements for the first 
implementation period SIPs (other than BART) are laid out in 40 CFR 
51.308(d). Those provisions required that states containing Class I 
areas establish reasonable progress goals (RPGs) that are measured in 
deciviews and reflect the anticipated visibility conditions at the end 
of the implementation period including from implementation of states' 
long-term strategies. The first planning period \7\ RPGs were required 
to provide for an improvement in visibility for the most impaired days 
over the period of the implementation plan and ensure no degradation in 
visibility for the least impaired days over the same period. In 
establishing the RPGs for any Class I area in a state, the state was 
required to consider four statutory factors: the costs of compliance, 
the time necessary for compliance, the energy and non-air quality 
environmental impacts of compliance, and the remaining useful life of 
any potentially affected sources. CAA 169A(g)(1); 40 CFR 51.308(d)(1).
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    \7\ The EPA uses the terms ``implementation period'' and 
``planning period'' interchangeably.
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    States were also required to calculate baseline (using the five-
year period of 2000-2004) and natural visibility conditions (i.e., 
visibility conditions without anthropogenic visibility impairment) for 
each Class I area, and to calculate the linear rate of progress needed 
to attain natural visibility conditions, assuming a starting point of 
baseline visibility conditions in 2004 and ending with natural 
conditions in 2064. This linear interpolation is known as the uniform 
rate of progress (URP) and is used as a tracking metric to help states 
assess the amount of progress they are making towards the national 
visibility goal over time in each Class I area.\8\ 40 CFR 
51.308(d)(1)(i)(B), (d)(2).

[[Page 56696]]

The 1999 RHR also provided that states' long-term strategies must 
include the ``enforceable emissions limitations, compliance schedules, 
and other measures as necessary to achieve the reasonable progress 
goals.'' 40 CFR 51.308(d)(3). In establishing their long-term 
strategies, states are required to consult with other states that also 
contribute to visibility impairment in a given Class I area and include 
all measures necessary to obtain their shares of the emission 
reductions needed to meet the RPGs. 40 CFR 51.308(d)(3)(i), (ii). 
Section 51.308(d) also contains seven additional factors states must 
consider in formulating their long-term strategies, 40 CFR 
51.308(d)(3)(v), as well as provisions governing monitoring and other 
implementation plan requirements. 40 CFR 51.308(d)(4). Finally, the 
1999 RHR required states to submit periodic progress reports--SIP 
revisions due every five years that contain information on states' 
implementation of their regional haze plans and an assessment of 
whether anything additional is needed to make reasonable progress, see 
40 CFR 51.308(g), (h)--and to consult with the Federal Land Manager(s) 
\9\ (FLMs) responsible for each Class I area according to the 
requirements in CAA 169A(d) and 40 CFR 51.308(i).
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    \8\ The EPA established the URP framework in the 1999 RHR to 
provide ``an equitable analytical approach'' to assessing the rate 
of visibility improvement at Class I areas across the country. The 
starting point for the URP analysis is 2004 and the endpoint was 
calculated based on the amount of visibility improvement that was 
anticipated to result from implementation of existing CAA programs 
over the period from the mid-1990s to approximately 2005. Assuming 
this rate of progress would continue into the future, the EPA 
determined that natural visibility conditions would be reached in 60 
years, or 2064 (60 years from the baseline starting point of 2004). 
However, the EPA did not establish 2064 as the year by which the 
national goal must be reached. 64 FR at 35731-32. That is, the URP 
and the 2064 date are not enforceable targets but are rather tools 
that ``allow for analytical comparisons between the rate of progress 
that would be achieved by the state's chosen set of control measures 
and the URP.'' (82 FR 3078, 3084, January 10, 2017).
    \9\ The EPA's regulations define ``Federal Land Manager'' as 
``the Secretary of the department with authority over the Federal 
Class I area (or the Secretary's designee) or, with respect to 
Roosevelt-Campobello International Park, the Chairman of the 
Roosevelt-Campobello International Park Commission.'' 40 CFR 51.301.
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    On January 10, 2017, the EPA promulgated revisions to the RHR, (82 
FR 3078, January 10, 2017), that apply for the second and subsequent 
implementation periods. The 2017 rulemaking made several changes to the 
requirements for regional haze SIPs to clarify states' obligations and 
streamline certain regional haze requirements. The revisions to the 
regional haze program for the second and subsequent implementation 
periods focused on the requirement that states' SIPs contain long-term 
strategies for making reasonable progress towards the national 
visibility goal in line with CAA 169A(b)(2)(B). The reasonable progress 
requirements as revised in the 2017 rulemaking (referred to here as the 
2017 RHR Revisions) are codified at 40 CFR 51.308(f). Among other 
changes, the 2017 RHR Revisions adjusted the deadline for states to 
submit their second implementation period SIPs from July 31, 2018, to 
July 31, 2021, clarified the order of analysis and the relationship 
between RPGs and the long-term strategy, and focused on making 
visibility improvements on the days with the most anthropogenic 
visibility impairment, as opposed to the days with the most visibility 
impairment overall. The EPA also revised requirements of the visibility 
protection program related to periodic progress reports and FLM 
consultation. The specific requirements applicable to second 
implementation period regional haze SIP submissions are addressed in 
detail below.
    The EPA provided guidance to the states for their second 
implementation period SIP submissions in the preamble to the 2017 RHR 
Revisions as well as in subsequent, stand-alone guidance documents. In 
August 2019, the EPA issued ``Guidance on Regional Haze State 
Implementation Plans for the Second Implementation Period'' (``2019 
Guidance'').\10\ On July 8, 2021, the EPA issued a memorandum 
containing ``Clarifications Regarding Regional Haze State 
Implementation Plans for the Second Implementation Period'' (``2021 
Clarifications Memo'').\11\ Additionally, the EPA further clarified the 
recommended procedures for processing ambient visibility data and 
optionally adjusting the URP to account for international anthropogenic 
and prescribed fire impacts in two technical guidance documents: the 
December 2018 ``Technical Guidance on Tracking Visibility Progress for 
the Second Implementation Period of the Regional Haze Program'' (``2018 
Visibility Tracking Guidance''),\12\ and the June 2020 ``Recommendation 
for the Use of Patched and Substituted Data and Clarification of Data 
Completeness for Tracking Visibility Progress for the Second 
Implementation Period of the Regional Haze Program'' and associated 
Technical Addendum (``2020 Data Completeness Memo'').\13\
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    \10\ Guidance on Regional Haze State Implementation Plans for 
the Second Implementation Period. https://www.epa.gov/visibility/guidance-regional-haze-state-implementation-plans-second-implementation-period. The EPA Office of Air Quality Planning and 
Standards, Research Triangle Park (August 20, 2019).
    \11\ Clarifications Regarding Regional Haze State Implementation 
Plans for the Second Implementation Period. https://www.epa.gov/system/files/documents/2021-07/clarifications-regarding-regional-haze-state-implementation-plans-for-the-second-implementation-period.pdf. The EPA Office of Air Quality Planning and Standards, 
Research Triangle Park (July 8, 2021).
    \12\ Technical Guidance on Tracking Visibility Progress for the 
Second Implementation Period of the Regional Haze Program. https://www.epa.gov/visibility/technical-guidance-tracking-visibility-progress-second-implementation-period-regional. The EPA Office of 
Air Quality Planning and Standards, Research Triangle Park. 
(December 20, 2018).
    \13\ Recommendation for the Use of Patched and Substituted Data 
and Clarification of Data Completeness for Tracking Visibility 
Progress for the Second Implementation Period of the Regional Haze 
Program. https://www.epa.gov/visibility/memo-and-technical-addendum-ambient-data-usage-and-completeness-regional-haze-program. The EPA 
Office of Air Quality Planning and Standards, Research Triangle Park 
(June 3, 2020).
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    As explained in the 2021 Clarifications Memo, the EPA intends the 
second implementation period of the regional haze program to secure 
meaningful reductions in visibility impairing pollutants that build on 
the significant progress states have achieved to date. The Agency also 
recognizes that analyses regarding reasonable progress are state-
specific and that, based on states' and sources' individual 
circumstances, what constitutes reasonable reductions in visibility 
impairing pollutants will vary from state-to-state. While there exist 
many opportunities for states to leverage both ongoing and upcoming 
emission reductions under other CAA programs, the Agency expects states 
to undertake rigorous reasonable progress analyses that identify 
further opportunities to advance the national visibility goal 
consistent with the statutory and regulatory requirements. See 
generally 2021 Clarifications Memo. This is consistent with Congress's 
determination that a visibility protection program is needed in 
addition to the CAA's National Ambient Air Quality Standards and 
Prevention of Significant Deterioration programs, as further emission 
reductions may be necessary to adequately protect visibility in Class I 
areas throughout the country.\14\
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    \14\ See, e.g., H.R. Rep. No. 95-294 at 205 (``In determining 
how to best remedy the growing visibility problem in these areas of 
great scenic importance, the committee realizes that as a matter of 
equity, the national ambient air quality standards cannot be revised 
to adequately protect visibility in all areas of the country.''), 
(``the mandatory Class I increments of [the PSD program] do not 
adequately protect visibility in Class I areas'').

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[[Page 56697]]

B. Roles of Agencies in Addressing Regional Haze

    Because the air pollutants and pollution affecting visibility in 
Class I areas can be transported over long distances, successful 
implementation of the regional haze program requires long-term, 
regional coordination among multiple jurisdictions and agencies that 
have responsibility for Class I areas and the emissions that impact 
visibility in those areas. To address regional haze, states need to 
develop strategies in coordination with one another, considering the 
effect of emissions from one jurisdiction on the air quality in 
another. Five regional planning organizations (RPOs),\15\ which include 
representation from state and Tribal governments, the EPA, and FLMs, 
were developed in the lead-up to the first implementation period to 
address regional haze. RPOs evaluate technical information to better 
understand how emissions from state and tribal land impact Class I 
areas across the country, pursue the development of regional strategies 
to reduce emissions of particulate matter and other pollutants leading 
to regional haze, and help states meet the consultation requirements of 
the RHR.
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    \15\ RPOs are sometimes also referred to as ``multi-
jurisdictional organizations,'' or MJOs. For the purposes of this 
document, the terms RPO and MJO are synonymous.
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    The Western Regional Air Partnership (WRAP), one of the five RPOs 
described in the previous paragraph, is a collaborative effort of state 
governments, local air agencies, tribal governments, and various 
federal agencies established to initiate and coordinate activities 
associated with the management of regional haze, visibility, and other 
air quality issues in the western United States. Members include the 
states of Alaska, Arizona, California, Colorado, Hawaii, Idaho, 
Montana, Nevada, New Mexico, North Dakota, Oregon, South Dakota, Utah, 
Washington, Wyoming, and 28 tribal governments.\16\ The federal partner 
members of WRAP are the EPA, U.S. National Parks Service (NPS), U.S. 
Fish and Wildlife Service (USFWS), U.S. Forest Service (USFS), and the 
U.S. Bureau of Land Management (BLM).
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    \16\ A full list of WRAP members is available at https://www.westar.org/wrap-council-members/.
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C. North Dakota's First Implementation Period SIP Submissions

    The governor of North Dakota submitted North Dakota's Regional Haze 
SIP for the first implementation period to the EPA on March 3, 2010, 
followed by SIP Supplement No. 1 submitted on July 27, 2010, and SIP 
Amendment No. 1 submitted on July 28, 2011 (collectively, the ``2010 
Regional Haze SIP''). On April 6, 2012, the EPA promulgated a final 
rule titled ``Approval and Promulgation of Implementation Plans; North 
Dakota; Regional Haze State Implementation Plan; Federal Implementation 
Plan for Interstate Transport of Pollution Affecting Visibility and 
Regional Haze; Final Rule'' (2012 Final Rule).\17\ The 2012 Final Rule 
approved in part and disapproved in part the 2010 Regional Haze SIP. 
The EPA's disapproval included portions of the plan that addressed 
reasonable progress requirements and North Dakota's BART determinations 
for Coal Creek Station (Coal Creek) Units 1 and 2 and Antelope Valley 
Station (Antelope Valley) Units 1 and 2. In the same rulemaking, the 
EPA promulgated a FIP that imposed, among other things, a 
NOX emission limit for Antelope Valley Units 1 and 2, and a 
NOX BART determination and emission limit for Coal Creek 
Units 1 and 2.
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    \17\ 77 FR 20894 (April 6, 2012).
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    Subsequently, North Dakota and other petitioners challenged the 
2012 Final Rule in the United States Court of Appeals for the Eighth 
Circuit. On January 2, 2013, North Dakota submitted a SIP revision to 
the EPA to provide additional information supporting its original 
NOX BART determination for Coal Creek.\18\ On September 23, 
2013, the Eighth Circuit concluded in North Dakota v. EPA that the EPA 
properly disapproved portions of the 2010 Regional Haze SIP, including 
the reasonable progress determination for Antelope Valley Units 1 and 
2.\19\ The court also upheld the EPA's FIP promulgating an emission 
limit of 0.17 lb/MMBtu NOX (30-day rolling average) for 
Antelope Valley Units 1 and 2.\20\ However, the court vacated and 
remanded the EPA's FIP promulgating an emission limit of 0.13 lb/MMBtu 
NOX (30-day rolling average) for Coal Creek.\21\
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    \18\ North Dakota referred to the January 2, 2013 SIP submission 
as ``Supplement No. 2.'' The EPA herein refers to North Dakota's 
January 2, 2013 submission as a SIP submission.
    \19\ North Dakota v. EPA, 730 F.3d 750, 766 (8th Cir. 2013).
    \20\ Id.
    \21\ Id. at 764.
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    Several SIP submissions and EPA actions for the first 
implementation period followed the Eighth Circuit's decision. On 
January 12, 2015, North Dakota submitted a SIP revision for a regional 
haze five-year progress report, pursuant to 40 CFR 51.308(g). On April 
26, 2018, the EPA proposed to approve the Coal Creek NOX 
BART determination submitted in North Dakota's January 2013 SIP 
submission.\22\ The EPA did not finalize that action.23 24 
On August 3, 2020, North Dakota submitted a SIP revision to incorporate 
the 2012 FIP requirements for Antelope Valley, which the EPA approved 
on April 5, 2022.\25\ In the same action, the EPA withdrew from the 
Code of Federal Regulations the FIP requirements for Coal Creek that 
the Eighth Circuit vacated in North Dakota v. EPA.
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    \22\ 83 FR 18248 (April 26, 2018).
    \23\ North Dakota's 2022 SIP submission, Letter from North 
Dakota Governor Doug Burgum to EPA Administrator Michael Regan.
    \24\ As explained in this document in section II.D., North 
Dakota subsequently withdrew the Coal Creek Station NOX 
BART portion of its 2013 SIP submission in its 2022 SIP submission 
to the EPA that included a revised NOX BART determination 
for Coal Creek. The EPA is acting on the Coal Creek Station 
NOX BART portion of the 2022 SIP submission in a separate 
action.
    \25\ 87 FR 19635 (April 5, 2022).
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D. North Dakota's Second Implementation Period SIP Submissions

    In accordance with CAA section 169A and the RHR at 40 CFR 
51.308(f), on August 11, 2022, the governor of North Dakota submitted 
North Dakota's 2022 SIP submission to address the State's regional haze 
obligations for the second implementation period, which runs through 
2028. North Dakota's 2022 SIP submission also addressed the first 
planning period NOX BART determination for Coal Creek that 
was remanded in North Dakota v. EPA. Concurrently, North Dakota also 
withdrew its 2013 SIP submission that addressed NOX BART for 
Coal Creek.\26\ The EPA is acting on North Dakota's 2022 SIP submission 
as it pertains to Coal Creek NOX BART and North Dakota's 
2015 SIP submission for the five-year progress report in a separate 
action.
---------------------------------------------------------------------------

    \26\ North Dakota refers to its January 2, 2013, SIP submission 
as SIP Supplement No. 2.
---------------------------------------------------------------------------

III. Requirements for Regional Haze Plans for the Second Implementation 
Period

    Under the CAA and the EPA's regulations, all 50 states, the 
District of Columbia, and the U.S. Virgin Islands are required to 
submit regional haze SIPs satisfying the applicable requirements for 
the second implementation period of the regional haze program by July 
31, 2021. Each state's SIP must contain a long-term strategy for making 
reasonable progress toward meeting the national goal of remedying any 
existing and preventing any future anthropogenic visibility impairment 
in Class I areas. CAA 169A(b)(2)(B). To this end, Sec.  51.308(f) lays 
out the process by which states

[[Page 56698]]

determine what constitutes their long-term strategies, with the order 
of the requirements in Sec.  51.308(f)(1) through (3) generally 
mirroring the order of the steps in the reasonable progress analysis 
\27\ and (f)(4) through (6) containing additional, related 
requirements. Broadly speaking, a state first must identify the Class I 
areas within the state and determine the Class I areas outside the 
state in which visibility may be affected by emissions from the state. 
These are the Class I areas that must be addressed in the state's long-
term strategy. See 40 CFR 51.308(f), (f)(2). For each Class I area 
within its borders, a state must then calculate the baseline, current, 
and natural visibility conditions for that area, as well as the 
visibility improvement made to date and the URP. See 40 CFR 
51.308(f)(1). Each state having a Class I area and/or emissions that 
may affect visibility in a Class I area must then develop a long-term 
strategy that includes the enforceable emission limitations, compliance 
schedules, and other measures that are necessary to make reasonable 
progress in such areas. A reasonable progress determination is based on 
applying the four factors in CAA section 169A(g)(1) to sources of 
visibility impairing pollutants that the state has selected to assess 
for controls for the second implementation period. Additionally, as 
further explained below, the RHR at 40 CFR 51.3108(f)(2)(iv) separately 
provides five ``additional factors'' \28\ that states must consider in 
developing their long-term strategies. See 40 CFR 51.308(f)(2). A state 
evaluates potential emission reduction measures for those selected 
sources and determines which are necessary to make reasonable progress. 
Those measures are then incorporated into the state's long-term 
strategy. After a state has developed its long-term strategy, it then 
establishes RPGs for each Class I area within its borders by modeling 
the visibility impacts of all reasonable progress controls at the end 
of the second implementation period, i.e., in 2028, as well as the 
impacts of other requirements of the CAA. The RPGs include reasonable 
progress controls not only for sources in the state in which the Class 
I area is located, but also for sources in other states that contribute 
to visibility impairment in that area. The RPGs are then compared to 
the baseline visibility conditions and the URP to ensure that progress 
is being made towards the statutory goal of preventing any future and 
remedying any existing anthropogenic visibility impairment in Class I 
areas. 40 CFR 51.308(f)(2)-(3).
---------------------------------------------------------------------------

    \27\ The EPA explained in the 2017 RHR Revisions that we were 
adopting new regulatory language in 40 CFR 51.308(f) that, unlike 
the structure in Sec.  51.308(d), ``tracked the actual planning 
sequence.'' (82 FR at 3091).
    \28\ The five ``additional factors'' for consideration in Sec.  
51.308(f)(2)(iv) are distinct from the four factors listed in CAA 
section 169A(g)(1) and 40 CFR 51.308(f)(2)(i) that states must 
consider and apply to sources in determining reasonable progress.
---------------------------------------------------------------------------

    In addition to satisfying the requirements at 40 CFR 51.308(f) 
related to reasonable progress, the regional haze SIP revisions for the 
second implementation period must address the requirements in Sec.  
51.308(g)(1) through (5) pertaining to periodic reports describing 
progress towards the RPGs, 40 CFR 51.308(f)(5), as well as requirements 
for FLM consultation that apply to all visibility protection SIPs and 
SIP revisions. 40 CFR 51.308(i).
    A state must submit its regional haze SIP and subsequent SIP 
revisions to the EPA according to the requirements applicable to all 
SIP revisions under the CAA and the EPA's regulations. See CAA 
169A(b)(2); CAA 110(a). Upon approval by the EPA, a SIP is enforceable 
by the Agency and the public under the CAA. If the EPA finds that a 
state fails to make a required SIP revision, or if the EPA finds that a 
state's SIP is incomplete or if it disapproves the SIP, the Agency must 
promulgate a federal implementation plan (FIP) that satisfies the 
applicable requirements. CAA 110(c)(1).

A. Identification of Class I Areas

    The first step in developing a regional haze SIP is for a state to 
determine which Class I areas, in addition to those within its borders, 
``may be affected'' by emissions from within the state. In the 1999 
RHR, the EPA determined that all states contribute to visibility 
impairment in at least one Class I area, 64 FR at 35720-22, and 
explained that the statute and regulations lay out an ``extremely low 
triggering threshold'' for determining ``whether States should be 
required to engage in air quality planning and analysis as a 
prerequisite to determining the need for control of emissions from 
sources within their State.'' Id. at 35721.
    A state must determine which Class I areas must be addressed by its 
SIP by evaluating the total emissions of visibility impairing 
pollutants from all sources within the state. While the RHR does not 
require this evaluation to be conducted in any particular manner, EPA's 
2019 Guidance provides recommendations for how such an assessment might 
be accomplished, including by, where appropriate, using the 
determinations previously made for the first implementation period. 
2019 Guidance at 8-9. In addition, the determination of which Class I 
areas may be affected by a state's emissions is subject to the 
requirement in 40 CFR 51.308(f)(2)(iii) to ``document the technical 
basis, including modeling, monitoring, cost, engineering, and emissions 
information, on which the State is relying to determine the emission 
reduction measures that are necessary to make reasonable progress in 
each mandatory Class I Federal area it affects.''

B. Calculations of Baseline, Current, and Natural Visibility 
Conditions; Progress to Date; and the Uniform Rate of Progress

    As part of assessing whether a SIP submission for the second 
implementation period is providing for reasonable progress towards the 
national visibility goal, the RHR contains requirements in Sec.  
51.308(f)(1) related to tracking visibility improvement over time. The 
requirements of this section apply only to states having Class I areas 
within their borders; the required calculations must be made for each 
such Class I area. The EPA's 2018 Visibility Tracking Guidance \29\ 
provides recommendations to assist states in satisfying their 
obligations under Sec.  51.308(f)(1); specifically, in developing 
information on baseline, current, and natural visibility conditions, 
and in making optional adjustments to the URP to account for the 
impacts of international anthropogenic emissions and prescribed fires. 
See 82 FR at 3103-05.
---------------------------------------------------------------------------

    \29\ The 2018 Visibility Tracking Guidance references and relies 
on parts of the 2003 Tracking Guidance: ``Guidance for Tracking 
Progress Under the Regional Haze Rule,'' which can be found at 
https://www.epa.gov/sites/default/files/2021-03/documents/tracking.pdf.
---------------------------------------------------------------------------

    The RHR requires tracking of visibility conditions on two sets of 
days: the clearest and the most impaired days. Visibility conditions 
for both sets of days are expressed as the average deciview index for 
the relevant five-year period (the period representing baseline or 
current visibility conditions). The RHR provides that the relevant sets 
of days for visibility tracking purposes are the 20% clearest (the 20% 
of monitored days in a calendar year with the lowest values of the 
deciview index) and 20% most impaired days (the 20% of monitored days 
in a calendar year with the highest amounts of anthropogenic visibility 
impairment).\30\ 40 CFR 51.301. A state must calculate visibility 
conditions for both the 20% clearest and

[[Page 56699]]

20% most impaired days for the baseline period of 2000-2004 and the 
most recent five-year period for which visibility monitoring data are 
available (representing current visibility conditions). 40 CFR 
51.308(f)(1)(i), (iii). States must also calculate natural visibility 
conditions for the clearest and most impaired days,\31\ by estimating 
the conditions that would exist on those two sets of days absent 
anthropogenic visibility impairment. 40 CFR 51.308(f)(1)(ii). Using all 
these data, states must then calculate, for each Class I area, the 
amount of progress made since the baseline period (2000-2004) and how 
much improvement is left to achieve to reach natural visibility 
conditions.
---------------------------------------------------------------------------

    \30\ This document also refers to the 20% clearest and 20% most 
anthropogenically impaired days as the ``clearest'' and ``most 
impaired'' or ``most anthropogenically impaired'' days, 
respectively.
    \31\ The RHR at 40 CFR 51.308(f)(1)(ii) contains an error 
related to the requirement for calculating two sets of natural 
conditions values. The rule says ``most impaired days or the 
clearest days'' where it should say ``most impaired days and 
clearest days.'' This is an error that was intended to be corrected 
in the 2017 RHR Revisions but did not get corrected in the final 
rule language. This is supported by the preamble text at 82 FR at 
3098: ``In the final version of 40 CFR 51.308(f)(1)(ii), an 
occurrence of ``or'' has been corrected to ``and'' to indicate that 
natural visibility conditions for both the most impaired days and 
the clearest days must be based on available monitoring 
information.''
---------------------------------------------------------------------------

    Using the data for the set of most impaired days only, states must 
plot a line between visibility conditions in the baseline period and 
natural visibility conditions for each Class I area to determine the 
URP--the amount of visibility improvement, measured in deciviews, that 
would need to be achieved during each implementation period to achieve 
natural visibility conditions by the end of 2064. The URP is used in 
later steps of the reasonable progress analysis for informational 
purposes and to provide a non-enforceable benchmark against which to 
assess a Class I area's rate of visibility improvement.\32\ 
Additionally, in the 2017 RHR Revisions, the EPA provided states the 
option of proposing to adjust the endpoint of the URP to account for 
impacts of anthropogenic sources outside the United States and/or 
impacts of certain types of wildland prescribed fires. These 
adjustments, which must be approved by the EPA, are intended to avoid 
any perception that states should compensate for impacts from 
international anthropogenic sources and to give states the flexibility 
to determine that limiting the use of wildland-prescribed fire is not 
necessary for reasonable progress. 82 FR at 3107 footnote 116.
---------------------------------------------------------------------------

    \32\ Being on or below the URP is not a ``safe harbor''; i.e., 
achieving the URP does not mean that a Class I area is making 
``reasonable progress'' and does not relieve a state from using the 
four statutory factors to determine what level of control is needed 
to achieve such progress. See, e.g., 82 FR at 3093.
---------------------------------------------------------------------------

    The EPA's 2018 Visibility Tracking Guidance can be used to help 
satisfy the 40 CFR 51.308(f)(1) requirements, including in developing 
information on baseline, current, and natural visibility conditions, 
and in making optional adjustments to the URP. In addition, the 2020 
Data Completeness Memo provides recommendations on the data 
completeness language referenced in Sec.  51.308(f)(1)(i) and provides 
updated natural conditions estimates for each Class I area.

C. Long-Term Strategy for Regional Haze

    The core component of a regional haze SIP submission is a long-term 
strategy that addresses regional haze in each Class I area within a 
state's borders and each Class I area outside the state that may be 
affected by emissions from the state. The long-term strategy ``must 
include the enforceable emissions limitations, compliance schedules, 
and other measures that are necessary to make reasonable progress, as 
determined pursuant to (f)(2)(i) through (iv).'' 40 CFR 51.308(f)(2). 
The amount of progress that is ``reasonable progress'' is based on 
applying the four statutory factors in CAA section 169A(g)(1) in an 
evaluation of potential control options for sources of visibility 
impairing pollutants, which is referred to as a ``four-factor'' 
analysis.\33\ The outcome of that analysis is the emission reduction 
measures that a particular source or group of sources needs to 
implement to make reasonable progress towards the national visibility 
goal. See 40 CFR 51.308(f)(2)(i). Emission reduction measures that are 
necessary to make reasonable progress may be either new, additional 
control measures for a source, or they may be the existing emission 
reduction measures that a source is already implementing. See 2019 
Guidance at 43; 2021 Clarifications Memo at 8-10. Such measures must be 
represented by ``enforceable emissions limitations, compliance 
schedules, and other measures'' (i.e., any additional compliance tools) 
in a state's long-term strategy in its SIP. 40 CFR 51.308(f)(2).
---------------------------------------------------------------------------

    \33\ Four-factor analysis considers the four statutory factors 
specified in CAA 169A(g)(1) and 40 CFR 51.308(f)(2)(i).
---------------------------------------------------------------------------

    Section 51.308(f)(2)(i) provides the requirements for the four-
factor analysis. The first step of this analysis entails selecting the 
sources to be evaluated for emission reduction measures; to this end, 
the RHR requires states to consider ``major and minor stationary 
sources or groups of sources, mobile sources, and area sources'' of 
visibility impairing pollutants for potential four-factor control 
analysis. 40 CFR 51.308(f)(2)(i). A threshold question at this step is 
which visibility impairing pollutants will be analyzed. As the EPA 
previously explained, consistent with the first implementation period, 
the EPA generally expects that each state will analyze at least 
SO2 and NOX in selecting sources and determining 
control measures. See 2019 Guidance at 12, 2021 Clarifications Memo at 
4. A state that chooses not to consider at least these two pollutants 
should demonstrate why such consideration would be unreasonable. 2021 
Clarifications Memo at 4.
    While states have the option to analyze all sources, the 2019 
Guidance explains that ``an analysis of control measures is not 
required for every source in each implementation period,'' and that 
``[s]electing a set of sources for analysis of control measures in each 
implementation period is . . . consistent with the Regional Haze Rule, 
which sets up an iterative planning process and anticipates that a 
state may not need to analyze control measures for all its sources in a 
given SIP revision.'' 2019 Guidance at 9. However, given that source 
selection is the basis of all subsequent control determinations, a 
reasonable source selection process ``should be designed and conducted 
to ensure that source selection results in a set of pollutants and 
sources the evaluation of which has the potential to meaningfully 
reduce their contributions to visibility impairment.'' 2021 
Clarifications Memo at 3.
    The EPA explained in the 2021 Clarifications Memo that each state 
has an obligation to submit a long-term strategy that addresses the 
regional haze visibility impairment that results from emissions from 
within that state. Thus, source selection should focus on the in-state 
contribution to visibility impairment and be designed to capture a 
meaningful portion of the state's total contribution to visibility 
impairment in Class I areas. A state should not decline to select its 
largest in-state sources on the basis that there are even larger out-
of-state contributors. 2021 Clarifications Memo at 4.\34\
---------------------------------------------------------------------------

    \34\ Similarly, in responding to comments on the 2017 RHR 
Revisions the EPA explained that ``[a] state should not fail to 
address its many relatively low-impact sources merely because it 
only has such sources and another state has even more low-impact 
sources and/or some high impact sources.'' Responses to Comments on 
Protection of Visibility: Amendments to Requirements for State 
Plans; Proposed Rule (81 FR 26942, May 4, 2016) at 87-88.
---------------------------------------------------------------------------

    Thus, while states have discretion to choose any source selection

[[Page 56700]]

methodology that is reasonable, whatever choices they make should be 
reasonably explained. To this end, 40 CFR 51.308(f)(2)(i) requires that 
a state's SIP submission include ``a description of the criteria it 
used to determine which sources or groups of sources it evaluated.'' 
The technical basis for source selection, which may include methods for 
quantifying potential visibility impacts such as emissions divided by 
distance metrics, trajectory analyses, residence time analyses, and/or 
photochemical modeling, must also be appropriately documented, as 
required by 40 CFR 51.308(f)(2)(iii).
    Once a state has selected the set of sources, the next step is to 
determine the emissions reduction measures for those sources that are 
necessary to make reasonable progress for the second implementation 
period.\35\ This is accomplished by considering the four factors--``the 
costs of compliance, the time necessary for compliance, and the energy 
and nonair quality environmental impacts of compliance, and the 
remaining useful life of any existing source subject to such 
requirements.'' CAA 169A(g)(1). The EPA has explained that the four-
factor analysis is an assessment of potential emission reduction 
measures (i.e., control options) for sources; ``use of the terms 
`compliance' and `subject to such requirements' in section 169A(g)(1) 
strongly indicates that Congress intended the relevant determination to 
be the requirements with which sources would have to comply to satisfy 
the CAA's reasonable progress mandate.'' 82 FR at 3091. Thus, for each 
source it has selected for four-factor analysis,\36\ a state must 
consider a ``meaningful set'' of technically feasible control options 
for reducing emissions of visibility impairing pollutants. Id. at 3088. 
The 2019 Guidance provides that ``[a] state must reasonably pick and 
justify the measures that it will consider, recognizing that there is 
no statutory or regulatory requirement to consider all technically 
feasible measures or any particular measures. A range of technically 
feasible measures available to reduce emissions would be one way to 
justify a reasonable set.'' 2019 Guidance at 29.
---------------------------------------------------------------------------

    \35\ The CAA provides that, ``[i]n determining reasonable 
progress there shall be taken into consideration'' the four 
statutory factors. CAA 169A(g)(1). However, in addition to four-
factor analyses for selected sources, groups of sources, or source 
categories, a state may also consider additional emission reduction 
measures for inclusion in its long-term strategy, e.g., from other 
newly adopted, on-the-books, or on-the-way rules and measures for 
sources not selected for four-factor analysis for the second 
implementation period.
    \36\ ``Each source'' or ``particular source'' is used here as 
shorthand. While a source-specific analysis is one way of applying 
the four factors, neither the statute nor the RHR requires states to 
evaluate individual sources. Rather, states have ``the flexibility 
to conduct four-factor analyses for specific sources, groups of 
sources or even entire source categories, depending on state policy 
preferences and the specific circumstances of each state.'' 82 FR at 
3088. However, not all approaches to grouping sources for four-
factor analysis are necessarily reasonable; the reasonableness of 
grouping sources in any particular instance will depend on the 
circumstances and the manner in which grouping is conducted. If it 
is feasible to establish and enforce different requirements for 
sources or subgroups of sources, and if relevant factors can be 
quantified for those sources or subgroups, then states should make a 
separate reasonable progress determination for each source or 
subgroup. 2021 Clarifications Memo at 7-8.
---------------------------------------------------------------------------

    The EPA's 2021 Clarifications Memo provides further guidance on 
what constitutes a reasonable set of control options for consideration: 
``A reasonable four-factor analysis will consider the full range of 
potentially reasonable options for reducing emissions.'' 2021 
Clarifications Memo at 7. In addition to add-on controls and other 
retrofits (i.e., new emissions reduction measures for sources), the EPA 
explained that states should generally analyze efficiency improvements 
for sources' existing measures as control options in their four-factor 
analyses, as in many cases such improvements are reasonable given that 
they typically involve only additional operation and maintenance costs. 
Additionally, the 2021 Clarifications Memo provides that states that 
have assumed a higher emissions rate than a source has achieved or 
could potentially achieve using its existing measures should also 
consider lower emissions rates as potential control options. That is, a 
state should consider a source's recent actual and projected emission 
rates to determine if it could reasonably attain lower emission rates 
with its existing measures. If so, the state should analyze the lower 
emission rate as a control option for reducing emissions. 2021 
Clarifications Memo at 7. The EPA's recommendations to analyze 
potential efficiency improvements and achievable lower emission rates 
apply to both sources that have been selected for four-factor analysis 
and those that have forgone a four-factor analysis on the basis of 
existing ``effective controls.'' See 2021 Clarifications Memo at 5, 10.
    After identifying a reasonable set of potential control options for 
the sources it has selected, a state then collects information on the 
four factors with regard to each option identified. The EPA has also 
explained that, in addition to the four statutory factors, states have 
flexibility under the CAA and RHR to reasonably consider visibility 
benefits as an additional factor alongside the four statutory 
factors.\37\ The 2019 Guidance provides recommendations for the types 
of information that can be used to characterize the four factors (with 
or without visibility), as well as ways in which states might 
reasonably consider and balance that information to determine which of 
the potential control options is necessary to make reasonable progress. 
See 2019 Guidance at 30-36. The 2021 Clarifications Memo contains 
further guidance on how states can reasonably consider modeled 
visibility impacts or benefits in the context of a four-factor 
analysis. 2021 Clarifications Memo at 12-13, 14-15. Specifically, the 
EPA explained that while visibility can reasonably be used when 
comparing and choosing between multiple reasonable control options, it 
should not be used to summarily reject controls that are reasonable 
given the four statutory factors. 2021 Clarifications Memo at 13. 
Ultimately, while states have discretion to reasonably weigh the 
factors and to determine what level of control is needed, Sec.  
51.308(f)(2)(i) provides that a state ``must include in its 
implementation plan a description of . . . how the four factors were 
taken into consideration in selecting the measure for inclusion in its 
long-term strategy.''
---------------------------------------------------------------------------

    \37\ See, e.g., Responses to Comments on Protection of 
Visibility: Amendments to Requirements for State Plans; Proposed 
Rule (81 FR 26942, May 4, 2016), Docket ID Number EPA-HQ-OAR-2015-
0531, U.S. Environmental Protection Agency at 186; 2019 Guidance at 
36-37.
---------------------------------------------------------------------------

    As explained above, Sec.  51.308(f)(2)(i) requires states to 
determine the emission reduction measures for sources that are 
necessary to make reasonable progress by considering the four factors. 
Pursuant to Sec.  51.308(f)(2), measures that are necessary to make 
reasonable progress towards the national visibility goal must be 
included in a state's long-term strategy and in its SIP.\38\ If the 
outcome of a four-factor analysis is a new, additional emission 
reduction measure for a source, that new measure is necessary to make 
reasonable progress towards remedying existing anthropogenic visibility 
impairment and must be included in the SIP. If the

[[Page 56701]]

outcome of a four-factor analysis is that no new measures are 
reasonable for a source, continued implementation of the source's 
existing measures is generally necessary to prevent future emission 
increases and thus to make reasonable progress towards the second part 
of the national visibility goal: preventing future anthropogenic 
visibility impairment. See CAA 169A(a)(1). That is, when the result of 
a four-factor analysis is that no new measures are necessary to make 
reasonable progress, the source's existing measures are generally 
necessary to make reasonable progress and must be included in the SIP. 
However, there may be circumstances in which a state can demonstrate 
that a source's existing measures are not necessary to make reasonable 
progress. Specifically, if a state can demonstrate that a source will 
continue to implement its existing measures and will not increase its 
emissions rate, it may not be necessary to have those measures in the 
long-term strategy to prevent future emissions increases and future 
visibility impairment. The EPA's 2021 Clarifications Memo provides 
further explanation and guidance on how states may demonstrate that a 
source's existing measures are not necessary to make reasonable 
progress. See 2021 Clarifications Memo at 8-10. If the state can make 
such a demonstration, it need not include a source's existing measures 
in the long-term strategy or its SIP.
---------------------------------------------------------------------------

    \38\ States may choose to, but are not required to, include 
measures in their long-term strategies beyond just the emission 
reduction measures that are necessary for reasonable progress. See 
2021 Clarifications Memo at 16. For example, states with smoke 
management programs may choose to submit their smoke management 
plans to the EPA for inclusion in their SIPs but are not required to 
do so. See, e.g., 82 FR at 3108-09 (requirement to consider smoke 
management practices and smoke management programs under 40 CFR 
51.308(f)(2)(iv) does not require states to adopt such practices or 
programs into their SIPs, although they may elect to do so).
---------------------------------------------------------------------------

    As with source selection, the characterization of information on 
each of the factors is also subject to the documentation requirement in 
Sec.  51.308(f)(2)(iii). The reasonable progress analysis, including 
source selection, information gathering, characterization of the four 
statutory factors (and potentially visibility), balancing of the four 
factors, and selection of the emission reduction measures that 
represent reasonable progress, is a technically complex exercise, but 
also a flexible one that provides states with bounded discretion to 
design and implement approaches appropriate to their circumstances. 
Given this flexibility, Sec.  51.308(f)(2)(iii) plays an important 
function in requiring a state to document the technical basis for its 
decision making so that the public and the EPA can comprehend and 
evaluate the information and analysis the state relied upon to 
determine what emission reduction measures must be in place to make 
reasonable progress. The technical documentation must include the 
modeling, monitoring, cost, engineering, and emissions information on 
which the state relied to determine the measures necessary to make 
reasonable progress. This documentation requirement can be met through 
the provision of and reliance on technical analyses developed through a 
regional planning process, so long as that process and its output has 
been approved by all state participants. In addition to the explicit 
regulatory requirement to document the technical basis of their 
reasonable progress determinations, states are also subject to the 
general principle that those determinations must be reasonably moored 
to the statute.\39\ That is, a state's decisions about the emission 
reduction measures that are necessary to make reasonable progress must 
be consistent with the statutory goal of remedying existing and 
preventing future visibility impairment.
---------------------------------------------------------------------------

    \39\ See Arizona ex rel. Darwin v. U.S. EPA, 815 F.3d 519, 531 
(9th Cir. 2016); Nebraska v. EPA, 812 F.3d 662, 668 (8th Cir. 2016); 
North Dakota v. EPA, 730 F.3d 750, 761 (8th Cir. 2013); Oklahoma v. 
EPA, 723 F.3d 1201, 1206, 1208-10 (10th Cir. 2013); cf. Nat'l Parks 
Conservation Ass'n v. EPA, 803 F.3d 151, 165 (3d Cir. 2015); Alaska 
Dep't of Envtl. Conservation v. EPA, 540 U.S. 461, 485, 490 (2004).
---------------------------------------------------------------------------

    The four statutory factors (and potentially visibility) are used to 
determine what emission reduction measures for selected sources must be 
included in a state's long-term strategy for making reasonable 
progress. Additionally, the RHR at 40 CFR 51.3108(f)(2)(iv) separately 
provides five ``additional factors'' \40\ that states must consider in 
developing their long-term strategies: (1) Emission reductions due to 
ongoing air pollution control programs, including measures to address 
reasonably attributable visibility impairment; (2) measures to reduce 
the impacts of construction activities; (3) source retirement and 
replacement schedules; (4) basic smoke management practices for 
prescribed fire used for agricultural and wildland vegetation 
management purposes and smoke management programs; and (5) the 
anticipated net effect on visibility due to projected changes in point, 
area, and mobile source emissions over the period addressed by the 
long-term strategy. The 2019 Guidance provides that a state may satisfy 
this requirement by considering these additional factors in the process 
of selecting sources for four-factor analysis, when performing that 
analysis, or both, and that not every one of the additional factors 
needs to be considered at the same stage of the process. See 2019 
Guidance at 21. The EPA provided further guidance on the five 
additional factors in the 2021 Clarifications Memo, explaining that a 
state should generally not reject cost-effective and otherwise 
reasonable controls merely because there have been emission reductions 
since the first planning period owing to other ongoing air pollution 
control programs or merely because visibility is otherwise projected to 
improve at Class I areas. Additionally, states generally should not 
rely on these additional factors to summarily assert that the state has 
already made sufficient progress and, therefore, no sources need to be 
selected or no new controls are needed regardless of the outcome of 
four-factor analyses. 2021 Clarifications Memo at 13.
---------------------------------------------------------------------------

    \40\ The five ``additional factors'' for consideration in Sec.  
51.308(f)(2)(iv) are distinct from the four factors listed in CAA 
section 169A(g)(1) and 40 CFR 51.308(f)(2)(i) that states must 
consider and apply to sources in determining reasonable progress.
---------------------------------------------------------------------------

    Because the air pollution that causes regional haze crosses state 
boundaries, Sec.  51.308(f)(2)(ii) requires a state to consult with 
other states that also have emissions that are reasonably anticipated 
to contribute to visibility impairment in a given Class I area. 
Consultation allows for each state that impacts visibility in an area 
to share whatever technical information, analyses, and control 
determinations may be necessary to develop coordinated emission 
management strategies. This coordination may be managed through inter- 
and intra-RPO consultation and the development of regional emissions 
strategies; additional consultations between states outside of RPO 
processes may also occur. If a state, pursuant to consultation, agrees 
that certain measures (e.g., a certain emission limitation) are 
necessary to make reasonable progress at a Class I area, it must 
include those measures in its SIP. 40 CFR 51.308(f)(2)(ii)(A). 
Additionally, the RHR requires that states that contribute to 
visibility impairment at the same Class I area consider the emission 
reduction measures the other contributing states have identified as 
being necessary to make reasonable progress for their own sources. 40 
CFR 51.308(f)(2)(ii)(B). If a state has been asked to consider or adopt 
certain emission reduction measures, but ultimately determines those 
measures are not necessary to make reasonable progress, that state must 
document in its SIP the actions taken to resolve the disagreement. 40 
CFR 51.308(f)(2)(ii)(C). The EPA will consider the technical 
information and explanations presented by the submitting state and the 
state with which it disagrees when considering whether to approve the 
state's SIP. See id.; 2019 Guidance at 53. Under all circumstances, a 
state must document in

[[Page 56702]]

its SIP submission all substantive consultations with other 
contributing states. 40 CFR 51.308(f)(2)(ii)(C).

D. Reasonable Progress Goals

    Reasonable progress goals ``measure the progress that is projected 
to be achieved by the control measures states have determined are 
necessary to make reasonable progress based on a four-factor 
analysis.'' 82 FR at 3091. Their primary purpose is to assist the 
public and the EPA in assessing the reasonableness of states' long-term 
strategies for making reasonable progress towards the national 
visibility goal for Class I areas within the state. See 40 CFR 
51.308(f)(3)(iii)-(iv). States in which Class I areas are located must 
establish two RPGs, both in deciviews--one representing visibility 
conditions on the clearest days and one representing visibility on the 
most anthropogenically impaired days--for each area within their 
borders. 40 CFR 51.308(f)(3)(i). The two RPGs are intended to reflect 
the projected impacts, on the two sets of days, of the emission 
reduction measures the state with the Class I area, as well as all 
other contributing states, have included in their long-term strategies 
for the second implementation period.\41\ The RPGs also account for the 
projected impacts of implementing other CAA requirements, including 
non-SIP based requirements. Because RPGs are the modeled result of the 
measures in states' long-term strategies (as well as other measures 
required under the CAA), they cannot be determined before states have 
conducted their four-factor analyses and determined the control 
measures that are necessary to make reasonable progress. See 2021 
Clarifications Memo at 6.
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    \41\ RPGs are intended to reflect the projected impacts of the 
measures all contributing states include in their long-term 
strategies. However, due to the timing of analyses, control 
determinations by other states, and other on-going emissions 
changes, a particular state's RPGs may not reflect all control 
measures and emissions reductions that are expected to occur by the 
end of the implementation period. The 2019 Guidance provides 
recommendations for addressing the timing of RPG calculations when 
states are developing their long-term strategies on disparate 
schedules, as well as for adjusting RPGs using a post-modeling 
approach. 2019 Guidance at 47-48.
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    For the second implementation period, the RPGs are set for 2028. 
Reasonable progress goals are not enforceable targets, 40 CFR 
51.308(f)(3)(iii); rather, they ``provide a way for the states to check 
the projected outcome of the [long-term strategy] against the goals for 
visibility improvement.'' 2019 Guidance at 46. While states are not 
legally obligated to achieve the visibility conditions described in 
their RPGs, Sec.  51.308(f)(3)(i) requires that ``[t]he long-term 
strategy and the reasonable progress goals must provide for an 
improvement in visibility for the most impaired days since the baseline 
period and ensure no degradation in visibility for the clearest days 
since the baseline period.'' Thus, states are required to have emission 
reduction measures in their long-term strategies that are projected to 
achieve visibility conditions on the most impaired days that are better 
than the baseline period and that show no degradation on the clearest 
days compared to the clearest days from the baseline period. The 
baseline period for the purpose of this comparison is the baseline 
visibility condition--the annual average visibility condition for the 
period 2000-2004. See 40 CFR 51.308(f)(1)(i), 82 FR at 3097-98.
    So that RPGs may also serve as a metric for assessing the amount of 
progress a state is making towards the national visibility goal, the 
RHR requires states with Class I areas to compare the 2028 RPG for the 
most impaired days to the corresponding point on the URP line 
(representing visibility conditions in 2028 if visibility were to 
improve at a linear rate from conditions in the baseline period of 
2000-2004 to natural visibility conditions in 2064). If the most 
impaired days RPG in 2028 is above the URP (i.e., if visibility 
conditions are improving more slowly than the rate described by the 
URP), each state that contributes to visibility impairment in the Class 
I area must demonstrate, based on the four-factor analysis required 
under 40 CFR 51.308(f)(2)(i), that no additional emission reduction 
measures would be reasonable to include in its long-term strategy. 40 
CFR 51.308(f)(3)(ii). To this end, 40 CFR 51.308(f)(3)(ii) requires 
that each state contributing to visibility impairment in a Class I area 
that is projected to improve more slowly than the URP provide ``a 
robust demonstration, including documenting the criteria used to 
determine which sources or groups [of] sources were evaluated and how 
the four factors required by paragraph (f)(2)(i) were taken into 
consideration in selecting the measures for inclusion in its long-term 
strategy.'' The 2019 Guidance provides suggestions about how such a 
``robust demonstration'' might be conducted. See 2019 Guidance at 50-
51.
    The 2017 RHR, 2019 Guidance, and 2021 Clarifications Memo also 
explain that projecting an RPG that is on or below the URP based on 
only on-the-books and/or on-the-way control measures (i.e., control 
measures already required or anticipated before the four-factor 
analysis is conducted) is not a ``safe harbor'' from the CAA's and 
RHR's requirement that all states must conduct a four-factor analysis 
to determine what emission reduction measures constitute reasonable 
progress. The URP is a planning metric used to gauge the amount of 
progress made thus far and the amount left before reaching natural 
visibility conditions. However, the URP is not based on consideration 
of the four statutory factors and therefore cannot answer the question 
of whether the amount of progress being made in any particular 
implementation period is ``reasonable progress.'' See 82 FR at 3093, 
3099-3100; 2019 Guidance at 22; 2021 Clarifications Memo at 15-16.

E. Monitoring Strategy and Other State Implementation Plan Requirements

    Section 51.308(f)(6) requires states to have certain strategies and 
elements in place for assessing and reporting on visibility. Individual 
requirements under this section apply either to states with Class I 
areas within their borders, states with no Class I areas but that are 
reasonably anticipated to cause or contribute to visibility impairment 
in any Class I area, or both. A state with Class I areas within its 
borders must submit with its SIP revision a monitoring strategy for 
measuring, characterizing, and reporting regional haze visibility 
impairment that is representative of all Class I areas within the 
state. SIP revisions for such states must also provide for the 
establishment of any additional monitoring sites or equipment needed to 
assess visibility conditions in Class I areas, as well as reporting of 
all visibility monitoring data to the EPA at least annually. Compliance 
with the monitoring strategy requirement may be met through a state's 
participation in the Interagency Monitoring of Protected Visual 
Environments (IMPROVE) monitoring network, which is used to measure 
visibility impairment caused by air pollution at the 156 Class I areas 
covered by the visibility program. 40 CFR 51.308(f)(6), (f)(6)(i), 
(f)(6)(iv). The IMPROVE monitoring data is used to determine the 20% 
most anthropogenically impaired and 20% clearest sets of days every 
year at each Class I area and tracks visibility impairment over time.
    All states' SIPs must provide for procedures by which monitoring 
data and other information are used to determine the contribution of 
emissions from within the state to regional haze visibility impairment 
in affected Class I areas. 40 CFR 51.308(f)(6)(ii), (iii). Section 
51.308(f)(6)(v) further requires

[[Page 56703]]

that all states' SIPs provide for a statewide inventory of emissions of 
pollutants that are reasonably anticipated to cause or contribute to 
visibility impairment in any Class I area; the inventory must include 
emissions for the most recent year for which data are available and 
estimates of future projected emissions. States must also include 
commitments to update their inventories periodically. The inventories 
themselves do not need to be included as elements in the SIP and are 
not subject to the EPA's review as part of the Agency's evaluation of a 
SIP revision.\42\ All states' SIPs must also provide for any other 
elements, including reporting, recordkeeping, and other measures, that 
are necessary for states to assess and report on visibility. 40 CFR 
51.308(f)(6)(vi). Per the 2019 Guidance, a state may note in its 
regional haze SIP that its compliance with the Air Emissions Reporting 
Rule (AERR) in 40 CFR part 51, subpart A satisfies the requirement to 
provide for an emissions inventory for the most recent year for which 
data are available. To satisfy the requirement to provide estimates of 
future projected emissions, a state may explain in its SIP how 
projected emissions were developed for use in establishing RPGs for its 
own and nearby Class I areas.\43\
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    \42\ See ``Step 8: Additional requirements for regional haze 
SIPs'' in 2019 Guidance at 55.
    \43\ Id.
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    Separate from the requirements related to monitoring for regional 
haze purposes under 40 CFR 51.308(f)(6), the RHR also contains a 
requirement at Sec.  51.308(f)(4) related to any additional monitoring 
that may be needed to address visibility impairment in Class I areas 
from a single source or a small group of sources. This is called 
``reasonably attributable visibility impairment.'' \44\ Under this 
provision, if the EPA or the FLM of an affected Class I area has 
advised a state that additional monitoring is needed to assess 
reasonably attributable visibility impairment, the state must include 
in its SIP revision for the second implementation period an appropriate 
strategy for evaluating such impairment.
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    \44\ The EPA's visibility protection regulations define 
``reasonably attributable visibility impairment'' as ``visibility 
impairment that is caused by the emission of air pollutants from 
one, or a small number of sources.'' 40 CFR 51.301.
---------------------------------------------------------------------------

F. Requirements for Periodic Reports Describing Progress Towards the 
Reasonable Progress Goals

    Section 51.308(f)(5) requires a state's regional haze SIP revision 
to address the requirements of paragraphs 40 CFR 51.308(g)(1) through 
(5) so that the plan revision due in 2021 will serve also as a progress 
report addressing the period since submission of the progress report 
for the first implementation period. The regional haze progress report 
requirement is designed to inform the public and the EPA about a 
state's implementation of its existing long-term strategy and whether 
such implementation is in fact resulting in the expected visibility 
improvement. See 81 FR 26942, 26950 (May 4, 2016), (82 FR at 3119, 
January 10, 2017). To this end, every state's SIP revision for the 
second implementation period is required to describe the status of 
implementation of all measures included in the state's long-term 
strategy, including BART and reasonable progress emission reduction 
measures from the first implementation period, and the resulting 
emissions reductions. 40 CFR 51.308(g)(1) and (2).
    A core component of the progress report requirements is an 
assessment of changes in visibility conditions on the clearest and most 
impaired days. For second implementation period progress reports, Sec.  
51.308(g)(3) requires states with Class I areas within their borders to 
first determine current visibility conditions for each area on the most 
impaired and clearest days, 40 CFR 51.308(g)(3)(i), and then to 
calculate the difference between those current conditions and baseline 
(2000-2004) visibility conditions to assess progress made to date. See 
40 CFR 51.308(g)(3)(ii). States must also assess the changes in 
visibility impairment for the most impaired and clearest days since 
they submitted their first implementation period progress reports. See 
40 CFR 51.308(g)(3)(iii), (f)(5). Since different states submitted 
their first implementation period progress reports at different times, 
the starting point for this assessment will vary state by state.
    Similarly, states must provide analyses tracking the change in 
emissions of pollutants contributing to visibility impairment from all 
sources and activities within the state over the period since they 
submitted their first implementation period progress reports. See 40 
CFR 51.308(g)(4), (f)(5). Changes in emissions should be identified by 
the type of source or activity. Section 51.308(g)(5) also addresses 
changes in emissions since the period addressed by the previous 
progress report and requires states' SIP revisions to include an 
assessment of any significant changes in anthropogenic emissions within 
or outside the state. This assessment must explain whether these 
changes in emissions were anticipated and whether they have limited or 
impeded progress in reducing emissions and improving visibility 
relative to what the state projected based on its long-term strategy 
for the first implementation period.

G. Requirements for Federal Land Manager Coordination

    CAA section 169A(d) requires that before a state holds a public 
hearing on a proposed regional haze SIP revision, it must consult with 
the appropriate FLM or FLMs; pursuant to that consultation, the state 
must include a summary of the FLMs' conclusions and recommendations in 
the notice to the public. Consistent with this statutory requirement, 
the RHR also requires that states ``provide the [FLM] with an 
opportunity for consultation, in person and at a point early enough in 
the State's policy analyses of its long-term strategy emission 
reduction obligation so that information and recommendations provided 
by the [FLM] can meaningfully inform the State's decisions on the long-
term strategy.'' 40 CFR 51.308(i)(2). Consultation that occurs 120 days 
prior to any public hearing or public comment opportunity will be 
deemed ``early enough,'' but the RHR provides that in any event the 
opportunity for consultation must be provided at least 60 days before a 
public hearing or comment opportunity. This consultation must include 
the opportunity for the FLMs to discuss their assessment of visibility 
impairment in any Class I area and their recommendations on the 
development and implementation of strategies to address such 
impairment. 40 CFR 51.308(i)(2). For the EPA to evaluate whether FLM 
consultation meeting the requirements of the RHR has occurred, the SIP 
submission should include documentation of the timing and content of 
such consultation. The SIP revision submitted to the EPA must also 
describe how the state addressed any comments provided by the FLMs. 40 
CFR 51.308(i)(3). Finally, a SIP revision must provide procedures for 
continuing consultation between the state and FLMs regarding the 
state's visibility protection program, including development and review 
of SIP revisions, five-year progress reports, and the implementation of 
other programs having the potential to contribute to impairment of 
visibility in Class I areas. 40 CFR 51.308(i)(4).

IV. The EPA's Evaluation of North Dakota's Regional Haze Submission for 
the Second Implementation Period

    The EPA is proposing approval for the portions of North Dakota's 
2022 SIP submission relating to CAA 169A and 40 CFR 51.308(f)(1): 
calculations of baseline, current, and natural visibility

[[Page 56704]]

conditions, progress to date, and the uniform rate of progress; 40 CFR 
51.308(f)(4): reasonably attributable visibility impairment; 40 CFR 
51.308(f)(5): progress report requirements; and 40 CFR 51.308(f)(6): 
monitoring strategy and other implementation plan requirements. The EPA 
is proposing disapproval for the portions of North Dakota's 2022 SIP 
submission relating to CAA 169A and 40 CFR 51.308(f)(2): long-term 
strategy; 40 CFR 51.308(f)(3): reasonable progress goals; and 40 CFR 
51.308(i): FLM consultation.

A. Calculations of Baseline, Current, and Natural Visibility 
Conditions; Progress to Date; and the Uniform Rate of Progress Under 40 
CFR 51.308(f)(1)

    Section 51.308(f)(1) requires states to determine the following for 
``each mandatory Class I Federal area located within the State'': 
baseline visibility conditions for the most impaired and clearest days, 
natural visibility conditions for the most impaired and clearest days, 
progress to date for the most impaired and clearest days, the 
differences between current visibility conditions and natural 
visibility conditions, and the URP. This section also provides the 
option for states to propose adjustments to the URP line for a Class I 
area to account for visibility impacts from anthropogenic sources 
outside the United States and/or the impacts from wildland prescribed 
fires that were conducted for certain specified objectives. 40 CFR 
51.308(f)(1)(vi)(B).
    North Dakota has two Class I areas located within the state: 
Lostwood Wilderness Area and Theodore Roosevelt National Park. North 
Dakota included visibility condition determinations for these Class I 
areas in its 2022 SIP submission.
    In its 2022 SIP submission, North Dakota determined that Lostwood 
Wilderness Area has 2000-2004 baseline visibility conditions of 8.2 
deciviews on the 20% clearest days and 18.3 deciviews on the 20% most 
impaired days.\45\ North Dakota calculated an estimated natural 
background visibility of 2.9 deciviews on the 20% clearest days and 5.9 
deciviews on the 20% most impaired days.\46\ The current visibility 
conditions, which are based on 2014-2018 monitoring data, were 7.5 
deciviews on the clearest days and 16.2 deciviews on the most impaired 
days, which are 4.6 deciviews and 10.3 deciviews greater than natural 
conditions on the respective sets of days.\47\ North Dakota noted that 
while the five-year rolling average IMPROVE data from 2014-2018 
indicate that Lostwood Wilderness Area is 0.80 deciviews above the 
unadjusted URP, that data also show that the area is 0.77 deciviews 
below the URP when adjusted for international impacts and prescribed 
fire.\48\ When the URP is adjusted for these impacts, an annual 
decrease of 0.08 deciviews is needed to reach natural visibility on the 
20% most impaired days.\49\
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    \45\ North Dakota's 2022 SIP submission, 49, ``Table 6: 
``IMPROVE Sites Clearest and Most Impaired Days Values.''
    \46\ Id. at 49, ``Table 7: ``Natural Visibility for the Most 
Impaired and Clearest Days.''
    \47\ Id. at 50, ``Table 8: ``Current (2014-2018) Visibility for 
the Most Impaired and Clearest Days.''
    \48\ Id. at 52, ``Figure 17: LWA Most Impaired Days Progress 
from 2000-2018'' and ``Figure 21: LWA Most Impaired Days Progress 
with Adjusted Glidepath from 2000-2018.''
    \49\ Id. at 56, ``Figure 21: LWA Most Impaired Days Progress 
with Adjusted Glidepath from 2000-2018.''
---------------------------------------------------------------------------

    In its 2022 SIP submission, North Dakota determined that Theodore 
Roosevelt National Park has 2000-2004 baseline visibility conditions of 
7.8 deciviews on the 20% clearest days and 16.4 deciviews on the 20% 
most impaired days.\50\ North Dakota calculated an estimated natural 
background visibility of 3.0 deciviews on the 20% clearest days and 5.9 
deciviews on the 20% most impaired days.\51\ The current visibility 
conditions, which are based on 2014-2018 monitoring data, were 5.9 
deciviews on the clearest days and 14.1 deciviews on the most impaired 
days, which are 2.9 deciviews and 8.2 deciviews greater than natural 
conditions on the respective sets of days.\52\ North Dakota noted that 
while the five-year rolling average IMPROVE data from 2014-2018 
indicates that Theodore Roosevelt National Park is 0.80 deciviews above 
the unadjusted URP, the five-year rolling average IMPROVE data from 
2014-2018 indicates that the park is 1.17 deciviews below the URP when 
adjusted for international impacts and prescribed fire.\53\ When the 
URP is adjusted for these impacts, an annual decrease of 0.06 deciviews 
is needed to reach natural visibility on the 20% most impaired 
days.\54\
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    \50\ Id. at 49, ``Table 6: ``IMPROVE Sites Clearest and Most 
Impaired Days Values.''
    \51\ Id. at 49, ``Table 7: ``Natural Visibility for the Most 
Impaired and Clearest Days.''
    \52\ Id. at 50, ``Table 8: ``Current (2014-2018) Visibility for 
the Most Impaired and Clearest Days.''
    \53\ Id. at 53, ``Figure 18: TRNP Most Impaired Days Progress 
from 2000-2018'' and 57, ``Figure 22: TRNP Most Impaired Days 
Progress with Adjusted Glidepath from 2000-2018.''
    \54\ Id. at 57, ``Figure 22: TRNP Most Impaired Days Progress 
with Adjusted Glidepath from 2000-2018.''
---------------------------------------------------------------------------

    Based on this information, which is provided in section 3.2 of 
North Dakota's 2022 SIP submission, the EPA finds that the visibility 
condition calculations for Lostwood Wilderness Area and Theodore 
Roosevelt National Park meet the requirements of 40 CFR 51.308(f)(1). 
For this reason, the EPA proposes to approve the portions of North 
Dakota's 2022 SIP submission relating to 40 CFR 51.308(f)(1): 
calculations of baseline, current, and natural visibility conditions, 
progress to date, and the uniform rate of progress.

B. North Dakota's Long-Term Strategy Under CAA 169A and 40 CFR 
51.308(f)(2)

    Each state having a Class I area within its borders or emissions 
that may affect visibility in any Class I area outside the state must 
develop a long-term strategy for making reasonable progress towards the 
national visibility goal for each impacted Class I area. CAA 
169A(b)(2)(B). As explained in the Background section of this document, 
reasonable progress is achieved when all states contributing to 
visibility impairment in a Class I area are implementing the measures 
determined--through application of the four statutory factors to 
sources of visibility impairing pollutants--to be necessary to make 
reasonable progress. 40 CFR 51.308(f)(2)(i). Each state's long-term 
strategy must include the enforceable emission limitations, compliance 
schedules, and other measures that are necessary to make reasonable 
progress. 40 CFR 51.308(f)(2). All new (i.e., additional) measures that 
are the outcome of four-factor analyses are necessary to make 
reasonable progress and must be in the long-term strategy. If the 
outcome of a four-factor analysis and other measures necessary to make 
reasonable progress is that no new measures are reasonable for a 
source, that source's existing measures are necessary to make 
reasonable progress, unless the state can demonstrate that the source 
will continue to implement those measures and will not increase its 
emission rate. Existing measures that are necessary to make reasonable 
progress must also be in the long-term strategy. In developing its 
long-term strategy, a state must also consider the five additional 
factors in Sec.  51.308(f)(2)(iv). As part of its reasonable progress 
determinations, the state must describe the criteria used to

[[Page 56705]]

determine which sources or group of sources were evaluated (i.e., 
subjected to four-factor analysis) for the second implementation period 
and how the four factors were taken into consideration in selecting the 
emission reduction measures for inclusion in the long-term strategy. 40 
CFR 51.308(f)(2)(iii).
    States may rely on technical information developed by the RPOs of 
which they are members to select sources for four-factor analysis and 
to conduct that analysis, as well as to satisfy the documentation 
requirements under Sec.  51.308(f). Where an RPO has performed source 
selection and/or four-factor analyses (or considered the five 
additional factors in Sec.  51.308(f)(2)(iv)) for its member states, 
those states may rely on the RPO's analyses for the purpose of 
satisfying the requirements of Sec.  51.308(f)(2)(i) so long as the 
states have a reasonable basis to do so and all state participants in 
the RPO process have approved the technical analyses. 40 CFR 
51.308(f)(3)(iii). States may also satisfy the requirement of Sec.  
51.308(f)(2)(ii) to engage in interstate consultation with other states 
that have emissions that are reasonably anticipated to contribute to 
visibility impairment in a given Class I area under the auspices of 
intra- and inter-RPO engagement.
    The EPA is proposing to disapprove North Dakota's long-term 
strategy for the second planning period. As detailed in this notice of 
proposed rulemaking, we find that North Dakota has not met the 
requirements of CAA 169A(b)(2) and Sec.  51.308(f)(2) on two separate 
grounds: (1) it relied on non-statutory rationales to reject controls 
it evaluated under the four statutory factors at Coyote Station and 
Antelope Valley; and (2) it failed to consider the four factors for 
Coal Creek and unreasonably rejected controls at Coal Creek and Leland 
Olds.
1. North Dakota's Long-Term Strategy Under CAA 169A and 40 CFR 
51.308(f)(2)(i)
    Section 169A(b)(2) of the CAA requires each state in which any 
Class I area is located or ``the emissions from which may reasonably be 
anticipated to cause or contribute to any impairment of visibility'' in 
a Class I area to have a plan for making reasonable progress toward the 
national visibility goal. CAA section 169A(g)(1) specifies: ``[I]n 
determining reasonable progress there shall be taken into consideration 
the costs of compliance, the time necessary for compliance, and the 
energy and nonair quality environmental impacts of compliance, and the 
remaining useful life of any existing source subject to such 
requirements.'' \55\ The RHR implements this statutory requirement in 
40 CFR 51.308(f) for the second and subsequent planning periods for 
regional haze. 40 CFR 51.308(f) requires states to submit a long-term 
strategy that addresses regional haze visibility impairment for each 
mandatory Class I area within the state and for each mandatory Class I 
area located outside the state that may be affected by emissions from 
the state. 40 CFR 51.308(f)(2)(i) lays out the CAA 169A four-factor 
criteria for the evaluation and development of the long-term strategy.
---------------------------------------------------------------------------

    \55\ We refer to the CAA section 169A(g)(1) requirements as the 
four factors.
---------------------------------------------------------------------------

    In its 2022 SIP submission, North Dakota focused its control 
strategy analysis for the second planning period on emissions of 
NOX and SO2. NOX and SO2 
are the two main pollutants that react to form ammonium nitrates and 
ammonium sulfates, the main visibility impairing pollutants that affect 
visibility at Class I areas in North Dakota on the most impaired days. 
In North Dakota, point sources are the largest contributors to 
SO2 and NOX. Thus, North Dakota focused on 
existing point sources in this planning period. North Dakota also 
evaluated oil and gas upstream operations.
    North Dakota selected ten facilities for four-factor analysis: 
Coyote Station, Antelope Valley, Milton R. Young Station, Coal Creek 
Station, Leland Olds Station, Heskett Station, Little Knife Gas Plant, 
Tioga Gas Plant, Northern Border Compressor Station #4, and Synfuels. 
Based on an analysis of the four factors, North Dakota declined to 
require additional emissions limitations, compliance schedules, or 
control measures at the selected sources. It determined that existing 
measures for all ten facilities comprise what is necessary to make 
reasonable progress and included those measures in its long-term 
strategy for the second implementation period. As detailed below, we 
are proposing to disapprove North Dakota's long-term strategy because 
the State did not meet the requirements of CAA 169A(b)(2), CAA 
169A(g)(1), and 40 CFR 51.308(f)(2) by improperly relying on non-
statutory considerations in its evaluation of Coyote Station and 
Antelope Valley and unreasonably rejecting controls at Coal Creek and 
Leland Olds.
a. Reliance on Non-Statutory Considerations To Reject Reasonable 
Controls at Coyote Station and Antelope Valley
    Coyote Station and Antelope Valley are EGUs located in Mercer 
County, North Dakota. Coyote Station is a single unit EGU with a 
capacity to produce approximately 450 megawatts (MW) per hour of 
electricity. Antelope Valley is a two-unit EGU. Each unit at Antelope 
Valley has the capacity to produce approximately 470 MW per hour of 
electricity. For Coyote Station and Antelope Valley, North Dakota 
evaluated the time necessary for compliance, energy and nonair quality 
environmental impacts, and remaining useful life, ultimately concluding 
that these factors were not significant enough to eliminate any of the 
potential control measures the State identified. Of the four statutory 
factors, North Dakota considered the costs of compliance most heavily 
in its identification of controls for modeling review and to determine 
whether those controls are necessary for reasonable progress.\56\ For 
Coyote Station, North Dakota evaluated two sets of controls: (1) 
selective non-catalytic reduction (SNCR) for NOX control (at 
$1,700/ton of NOX removed) and replacement of the existing 
SO2 absorber (at $1,800/ton of SO2 removed), 
which are consistent with control technologies and emissions rates of 
similar EGUs subject to the BART requirements; and (2) modification of 
the flue gas desulfurization (FGD) controls for SO2 (at 
$400/ton of SO2 removed), which would limit capital 
expenditures and facility modifications.\57\ For Antelope Valley, North 
Dakota evaluated an SO2 control of increasing the 
stoichiometric ratio \58\ on the existing FGD (at $700/ton of 
SO2 removed), in line with control technologies and 
emissions rates of similar EGUs subject to the BART requirements; it 
did not select any NOX controls for evaluation.\59\
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    \56\ North Dakota's 2022 SIP submission at 99, 101.
    \57\ Id. at 99-100. North Dakota did not determine these costs 
to be unreasonable in its 2022 SIP submission.
    \58\ Stoichiometric ratio relates to the efficiency of the use 
of the reagent that reacts with SO2. Stoichiometric ratio 
is defined as moles of reagent per mole of SO2. 
Increasing the stoichiometric ratio will reduce the emission of 
SO2.
    \59\ North Dakota's 2022 SIP submission at 101-02. North Dakota 
did not determine the costs of the evaluated controls to be 
unreasonable in its 2022 SIP submission.
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    Following its evaluation of controls under the four-factor 
analysis, the State then conducted a visibility modeling evaluation to 
assess the visibility improvements that could result from installation 
of controls at Coyote Station

[[Page 56706]]

and Antelope Valley. North Dakota then declined to impose new emission 
limits on Coyote Station and Antelope Valley associated with the 
controls evaluated through its four-factor analysis, citing two 
separate bases: (1) the modeling showed no significant change in 
visibility at Lostwood Wilderness Area and Theodore Roosevelt National 
Park because improvements were smaller than could be perceived by an 
unaided human eye; and (2) Lostwood Wilderness Area and Theodore 
Roosevelt National Park were projected to achieve the adjusted URP by 
2028.\60\ North Dakota made no argument that the controls were not 
cost-effective. The State's rationales, whether individually or in 
combination, are not supported by the CAA and the RHR and do not 
justify North Dakota's rejection of cost-effective \61\ and otherwise 
reasonable controls at Coyote Station and Antelope Valley.
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    \60\ Id. at 100, 102.
    \61\ The 2019 Guidance emphasized that ``[w]hen the cost/ton of 
a possible measure is within the range of the cost/ton values that 
have been incurred multiple times by sources of similar type to meet 
regional haze requirements or any other CAA requirement, this weighs 
in favor of concluding that the cost of compliance is not an 
obstacle to the measure being considered necessary to make 
reasonable progress.'' 2019 Guidance at 40. The NOX and 
SO2 controls that North Dakota evaluated for Coyote 
Station and Antelope Valley range from $400/ton to $1800/ton. North 
Dakota did not determine these costs to be unreasonable. Indeed, 
these cost-effectiveness values are in line with--and in some cases 
well below--those the EPA and states found reasonable for regional 
haze control measures in the first planning period, even without 
adjusting for inflation. After evaluating first planning period cost 
of compliance values, plus the other BART statutory factors and/or 
the four reasonable progress statutory factors, the vast majority of 
cost/ton values <$2,500/ton were found to be reasonable and cost-
effective. This includes control determinations for sources both 
within North Dakota and in other states. Examples for several 
sources can be found at: 76 FR 16168, 16180-81 (Mar. 22, 2011) 
(proposed), finalized at 76 FR 81728 (Dec. 28, 2011) (Oklahoma); 76 
FR 58570, 58586 (Sept. 21, 2011) (proposed), finalized at 77 FR 
20894 (Apr. 6, 2012) (North Dakota); 77 FR 24794, 24817 (Apr. 25, 
2012) (proposed), finalized at 77 FR 51915 (Aug. 28, 2012) (New 
York); 77 FR 18052, 18070-71 (Mar. 26, 2012) (proposed), finalized 
at 77 FR 76871 (Dec. 31, 2012) (Colorado); and 77 FR 73369, 73378 
(Dec. 10, 2012) (proposed), finalized at 78 FR 53250 (Aug. 29, 2013) 
(Florida). The cited costs have not been adjusted for inflation.
---------------------------------------------------------------------------

i. North Dakota Unreasonably Rejected Controls Based on Visibility 
Modeling
    North Dakota used two emission control scenarios to model potential 
visibility improvements at Theodore Roosevelt National Park and 
Lostwood Wilderness. Visibility modeling for the first scenario 
(installing controls similar to BART at Coyote Station and increasing 
the stoichiometric ratio on the existing FGD unit at Antelope Valley) 
resulted in projected visibility improvement of 0.10 deciviews at 
Lostwood Wilderness Area and 0.08 deciviews at Theodore Roosevelt 
National Park. Visibility modeling for the second scenario (installing 
controls at Coyote Station based on ``limited capital expenditure and 
facility modifications, while still achieving sizeable [emission] 
reductions'') produced projected visibility improvement of 0.04 
deciviews at Lostwood Wilderness Area and 0.03 deciviews at Theodore 
Roosevelt National Park.\62\ North Dakota rejected both control 
scenarios for inclusion in its long-term strategy because these 
visibility improvements ``are not considered significant since the 
improvements are smaller than what is perceptible by an unaided human 
eye.'' \63\
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    \62\ North Dakota's 2022 SIP submission at 100.
    \63\ Id. at 100 (Coyote Station), 102 (Antelope Valley).
---------------------------------------------------------------------------

    As explained in section B.1.a.i.(a) below, we find that North 
Dakota unreasonably relied on visibility modeling to reject controls at 
Coyote Station and Antelope Valley. Whether visibility impacts are 
``significant'' or ``perceptible'' is not a sufficient basis to reject 
cost-effective and otherwise reasonable emission controls under the CAA 
and RHR. In addition, North Dakota's visibility analysis failed to 
account for visibility impacts at out-of-state Class I areas that may 
be affected by emissions from North Dakota.
(a) Modeling Showing No ``Significant'' Change in Visibility Is Not a 
Sufficient Basis To Reject Controls Under CAA 169A and 40 CFR 
51.308(f)(2)(i)
    North Dakota improperly rejected controls for Coyote Station and 
Antelope Valley that it evaluated via the four-factor analysis required 
by CAA 169A(g)(1) and 40 CFR 51.308(f)(2)(i) based on consideration of 
whether the visibility improvement from those controls would be 
``significant.'' The State's rationale lacks foundation in both the 
text and the purpose of the CAA and RHR. Nowhere in the statute or 
regulations is there a requirement that control measures produce 
perceptible visibility improvements to be considered necessary to make 
reasonable progress at a particular Class I area. The 2017 RHR 
explained: ``Regional haze is visibility impairment that is caused by 
the emission of air pollutants from numerous sources located over a 
wide geographic area. At any given Class I area, hundreds or even 
thousands of individual sources may contribute to regional haze. Thus, 
it would not be appropriate for a state to reject a control measure (or 
measures) because its effect on the RPG is subjectively assessed as not 
`meaningful.' '' \64\ Even though the visibility impacts of emissions 
from some individual sources may not be ``perceptible'' (as determined 
by North Dakota), those sources may still have a meaningful impact on 
visibility in the aggregate.\65\ Achieving Congress's national goal 
will require serious evaluation of control measures at Antelope Valley 
and Coyote Station, particularly because the largest individual 
contributors to visibility impairment have already been controlled or 
retired.\66\
---------------------------------------------------------------------------

    \64\ 82 FR at 3093.
    \65\ 2021 Clarifications Memo at 14.
    \66\ Id.
---------------------------------------------------------------------------

    After evaluating control measures for Coyote Station and Antelope 
Valley using four-factor analysis, North Dakota then determined, based 
on the results of visibility modeling, that those controls were not 
necessary to make reasonable progress toward meeting the national goal 
without tying that determination back to the four statutory factors. 
The CAA and RHR are clear that the four statutory factors must be 
considered when determining the enforceable emissions limitations, 
schedules of compliance, or other measures that are necessary for 
reasonable progress toward meeting the national goal. Nothing in the 
language of either the CAA or the RHR suggests that non-statutory 
factors, such as whether visibility improvement is ``perceptible'' or 
``significant,'' can outweigh the results of an analysis based on those 
factors explicitly prescribed in the statute. As the EPA has previously 
explained, states should not use visibility impacts to summarily 
dismiss cost-effective potential controls,\67\ as North Dakota has 
done.\68\ The EPA has interpreted the CAA and RHR to allow states to 
consider visibility alongside the four statutory factors. For example, 
visibility modeling can be used to compare the visibility benefits of 
cost-effective controls selected through four-factor analysis to 
determine which controls produce the greatest visibility benefits 
compared to their costs, or prioritizing which among several sources 
should install controls during a planning period.\69\ By contrast, 
North

[[Page 56707]]

Dakota employed the non-statutory factor of ``insignificant'' 
visibility benefit as the basis for rejecting controls, using it to 
outweigh controls shown to be reasonable by proper application of the 
four statutory factors. This is inconsistent with the CAA.
---------------------------------------------------------------------------

    \67\ Id. at 13.
    \68\ North Dakota's 2022 SIP submission at 100 (concluding that 
``[s]ince the modeling has indicated no expected significant change 
in visibility . . . the Department does not believe any additional 
SO2 or NOX controls at Coyote should be 
required for installation during this planning period''), 102 
(reaching same conclusion for Antelope Valley).
    \69\ 2021 Clarifications Memo at 12-13.
---------------------------------------------------------------------------

    Recent annual emissions data from EPA's Clean Air Markets Program 
Data also contradict North Dakota's conclusion that no controls are 
needed for Antelope Valley and Coyote Station due to the lack of 
``significant'' visibility improvement for otherwise cost-effective 
controls. In fact, Antelope Valley and Coyote Station ranked 17th and 
18th, respectively, in facility-wide SO2 emissions across 
the United States.\70\ Across all states, North Dakota's EGU 
SO2 emissions ranked 10th.\71\ The magnitude of 
SO2 emissions from Antelope Valley and Coyote Station 
specifically, as well as all of North Dakota's EGUs statewide, combined 
with the outcome of the four-factor analyses, emphasize that emission 
reductions at Antelope Valley and Coyote Station from additional 
SO2 controls could result in meaningful improvement at 
impacted Class I areas and achieve reasonable progress.
---------------------------------------------------------------------------

    \70\ ``CAMPD Emissions Custom Data Download,'' available in the 
docket for this action.
    \71\ Id.
---------------------------------------------------------------------------

    Additionally, even if using ``insignificant'' visibility benefit to 
outweigh the four statutory factors were allowable, North Dakota relied 
on an overly narrow analysis of the visibility modeling. The State 
considered projected visibility improvements only on the most impaired 
days, as opposed to analyzing projected visibility improvements for all 
of the days, to reject controls at Coyote Station and Antelope 
Valley.\72\ The CAA and RHR, however, require states to make reasonable 
progress toward both remedying any existing and preventing any future 
visibility impairment; focusing on only the most impaired days ignores 
the latter statutory directive.\73\ As the EPA has previously 
explained, assessing overall visibility impairment on the 20 percent 
most impaired and clearest days is the required metric for tracking 
visibility impairment at Class I areas.\74\ Assessing modeled 
visibility improvement on only the most impaired days may not 
accurately reflect individual sources' contribution to overall 
visibility impairment at Class I areas.\75\ Depending on wind direction 
and other meteorological factors, emissions from a single source may 
not always or frequently impact a particular Class I area, but there 
may be individual day visibility impacts that are important to consider 
(both within the set of 20 percent most impaired days and outside that 
set of days). Thus, the EPA has recommended examination of the maximum 
daily visibility impact on all days as a more meaningful metric for 
individual source visibility modeling.\76\
---------------------------------------------------------------------------

    \72\ North Dakota's 2022 SIP submission, 100, 102.
    \73\ CAA 169A(a)(1), (b)(2)(B), and (g)(1); 40 CFR 
51.308(f)(2)(i).
    \74\ 40 CFR 51.308(f)(1); 2019 Guidance at 15.
    \75\ 2019 Guidance at 15-16.
    \76\ Id.
---------------------------------------------------------------------------

    Finally, even if these values from the modeled visibility 
improvement projections adequately accounted for the important 
meteorological variability and other parameters, North Dakota 
improperly discounted these values in formulating its long-term 
strategy. Put into the proper context, visibility improvements in two 
Class I areas in the range of 0.03 to 0.04 deciviews (in the case of 
``limited capital expenditure'' controls at just one source, Coyote 
Station) and 0.08 to 0.10 deciviews (in the case of BART-consistent and 
modification-based controls at Coyote Station and Antelope Valley) may 
be considered a meaningful improvement. Because regional haze is caused 
by hundreds of thousands of sources across a wide geographic area, very 
few if any sources will individually have impacts that would meet a 
threshold considered perceptible to the human eye.\77\ Nonetheless, 
these impacts, even if not individually perceptible, have a meaningful 
impact on visibility in Class I areas in the aggregate.\78\
---------------------------------------------------------------------------

    \77\ 2021 Clarifications Memo at 14.
    \78\ Id.
---------------------------------------------------------------------------

(b) North Dakota Failed To Consider Visibility Impacts at Out-of-State 
Class I Areas
    North Dakota's reliance on visibility modeling to reject controls 
at Coyote Station and Antelope Valley is also unreasonable because it 
failed to consider visibility impacts at out-of-state Class I areas. 
North Dakota modeled potential visibility improvements only at its two 
in-state Class I areas: Theodore Roosevelt National Park and Lostwood 
Wilderness Area. However, the record shows that North Dakota sources 
are reasonably anticipated to cause or contribute to visibility 
impairment at out-of-state Class I areas including Medicine Lake 
Wilderness Area, Badlands National Park, Voyageurs National Park, and 
Boundary Waters Canoe Area Wilderness. North Dakota's evaluation of 
visibility improvements did not consider these out-of-state Class I 
areas; in fact, the long-term strategy chapter (section 5) of North 
Dakota's 2022 SIP submission does not even reference out-of-state Class 
I areas. Thus, North Dakota's evaluation of visibility improvements, 
which it relied on to determine that controls at Coyote Station and 
Antelope Valley are not necessary to make reasonable progress at Class 
I areas that may be affected by emissions from North Dakota, is not 
supported by the record.
    North Dakota's 2022 SIP submission includes numerous data points 
showing the impact of North Dakota sources on out-of-state Class I 
areas. However, it is not entirely clear whether North Dakota made a 
determination on whether its sources ``may reasonably be anticipated to 
cause or contribute to any impairment of visibility'' in those out-of-
state Class I areas.\79\ On the one hand, North Dakota asserted that 
``[d]ue to the insignificant impacts from North Dakota sources on out 
of state CIAs, no sources were identified as reasonably anticipated to 
impact out of state CIAs.'' \80\ On the other, North Dakota also 
repeatedly acknowledged, based on its review of WRAP visibility 
modeling data, that its sources potentially contribute to visibility 
impairment in several out-of-state Class I areas.\81\ Based on our 
review of WRAP Weighted Emission Potential (WEP) \82\ results, WRAP 
source-apportionment data available via WRAP's Technical Support System 
(TSS), and visibility impairment contribution modeling from Minnesota's 
2022 SIP submission, we find that North Dakota sources are reasonably 
anticipated to contribute to impairment in out-of-state Class I areas 
including Medicine Lake Wilderness Area, Badlands National Park, 
Voyageurs National Park, and Boundary Waters Canoe Area Wilderness. 
Thus, North Dakota was required to develop a long-term strategy that 
includes the emission reduction measures necessary to make reasonable 
progress in both in-state and out-of-state Class I areas that may be 
affected by emissions from North Dakota.
---------------------------------------------------------------------------

    \79\ CAA 169A(b)(2).
    \80\ North Dakota's 2022 SIP submission at 39.
    \81\ Id., appendix C.3.3-C.3.9, C.3.12-C.3.13, C.3.16.
    \82\ WEP is a quantitative method of analyzing how pollutants 
from particular sources may be transported to other areas.
---------------------------------------------------------------------------

    For impacts on Montana's Class I areas, North Dakota states in its 
2022 SIP submission that Figure 14 in appendix C.3-9 (WEP results for 
Medicine Lake Wilderness Area in Montana) ``shows that North Dakota EGU 
sources have some potential for impairment regarding SO2 and 
NOX.'' Also, in appendix C.3 of North Dakota's

[[Page 56708]]

2022 SIP submission, North Dakota states that ``Figure 15 demonstrates 
the potential for impairment from North Dakota oil and gas sources.'' 
In Figures 14 and 15, sources in the western half of North Dakota have 
ammonium nitrate and ammonium sulfate extinction weighted residence 
time impacts as large as 5 to 10% of the total extinction weighted 
residence time at Medicine Lake Wilderness Area.\83\ Thus, Figures 14 
and 15 clearly show potential for impairment of Medicine Lake 
Wilderness Area from both North Dakota EGU and oil and gas sources. 
North Dakota's own data, presented in Figures 14 and 15, demonstrates 
the potential for impairment of visibility at Medicine Lake Wilderness 
Area from sources within North Dakota.
---------------------------------------------------------------------------

    \83\ North Dakota's 2022 SIP submission, 42 (Figure 14) and 44 
(Figure 15). While there is no numerical threshold in the CAA or RHR 
for determining when a state ``may be reasonably anticipated to 
cause or contribute'' to a Class I area, the Ninth Circuit has 
interpreted the language ``may reasonably be anticipated to cause or 
contribute'' under CAA section 169A(b)(2) to establish an extremely 
low triggering threshold for requiring a source to control emissions 
for the purposes of addressing its impact on Class I areas. Central 
Arizona Water Conservation Dist. v. EPA, 990 F.2d 1531 (1993). The 
EPA referenced this decision in the 1999 Regional Haze Rule, noting 
that the court found that the language ``may reasonably be 
anticipated to cause or contribute'' establishes an ``extremely low 
triggering threshold'' for requiring a source to control emissions, 
adding that ``the NAS [National Academy of Sciences] correctly noted 
that Congress has not required ironclad scientific certainty 
establishing the precise relationship between a source's emission 
and resulting visibility impairment.'' 64 FR at 35721.
---------------------------------------------------------------------------

    In addition, the data in WRAP's TSS indicate that North Dakota 
sources are reasonably anticipated to impact Medicine Lake Wilderness 
Area. The EPA used WRAP's State Source Group Contributions to U.S. 
Anthropogenic Impairment tool for Medicine Lake Wilderness Area to 
analyze North Dakota sources' contribution to visibility impairment in 
that area. In terms of both ammonium sulfate extinction (0.86 
Mm-1) and ammonium nitrate extinction (0.99 
Mm-1), North Dakota had a greater impact on visibility 
impairment than any other WRAP state, including Montana (0.64 
Mm-1 ammonium nitrate extinction and 0.57 Mm-1 
ammonium sulfate extinction), where Medicine Lake Wilderness Area is 
located.\84\ Even with all this data, North Dakota did not consider the 
visibility impacts on Medicine Lake Wilderness Area when it rejected 
controls at Coyote Station and Antelope Valley, following four-factor 
analysis, on the basis that the associated visibility benefits at Class 
I areas were not significant enough to justify inclusion of those 
controls in its long-term strategy.
---------------------------------------------------------------------------

    \84\ ``TSS XY Chart--Product #XMTP_SASB_LUCS.'' WRAP Technical 
Support System (TSS); CSU and the Cooperative Institute for Research 
in the Atmosphere (CIRA), 04 Dec 2023.
---------------------------------------------------------------------------

    For impacts on South Dakota's Class I areas, North Dakota's 
analysis of WEP results indicates that in-state potential contributions 
to impairment to Badlands National Park are due to emissions from the 
EGU and oil and gas sectors. In Figure 21 of appendix C.3-13 of North 
Dakota's 2022 SIP submission, several sources in the western half of 
North Dakota show impacts greater than 0.5% to 10% of the total 
extinction weighted residence time at Badlands National Park.\85\ 
Figure 22 in North Dakota's 2022 SIP submission shows EGU ammonium 
nitrate and ammonium sulfate extinction weighted residence time impacts 
of 1 to 10% of the total extinction weighted residence time at Badlands 
National Park.\86\ In Figure 23, multiple grid cells in North Dakota 
with oil and gas sources show contributions of 1 to 3% of the total 
extinction weighted residence time at Badlands National Park.\87\
---------------------------------------------------------------------------

    \85\ See footnote 55.
    \86\ North Dakota's 2022 SIP submission, appendix C.3-13.
    \87\ Id.
---------------------------------------------------------------------------

    In addition, WRAP's State Source Group Contributions to US 
Anthropogenic Impairment tool for Badlands National Park shows that 
visibility impairing pollutants from North Dakota sources contribute 
more to visibility impairment at Badlands National Park than any other 
state. In fact, North Dakota sources have a greater contribution to 
visibility impairment at Badlands National Park than sources in South 
Dakota, where Badlands National Park is located.\88\ North Dakota 
sources contribute ammonium sulfate extinction of 0.74 Mm-1 
and ammonium nitrate extinction of 0.36 Mm-1, while South 
Dakota sources contribute ammonium sulfate extinction of 0.03 
Mm-1 and ammonium nitrate extinction of 0.13 
Mm-1.\89\ Here too, North Dakota failed to consider 
visibility impacts on Badlands National Park when it rejected controls 
at Coyote Station and Antelope Valley, following four-factor analysis, 
on the basis that the associated visibility benefits at Class I areas 
were not significant enough to justify inclusion of those controls in 
its long-term strategy.
---------------------------------------------------------------------------

    \88\ ``TSS XY Chart--Product #XMTP_SASB_LUCS.'' WRAP Technical 
Support System (TSS); CSU and the Cooperative Institute for Research 
in the Atmosphere (CIRA), 04 Dec 2023.
    \89\ Id.
---------------------------------------------------------------------------

    For impacts on Minnesota Class I areas, North Dakota states in 
Figure 10 in appendix C.3-7 of its 2022 SIP submission (WEP results for 
Voyageurs National Park in Minnesota) that ``North Dakota EGU sources 
show some potential for impairment regarding SO2.'' \90\ 
North Dakota considered the WEP results at Voyageurs National Park as 
reflective of the impairment at Boundary Waters Canoe Area Wilderness 
and did not perform a separate WEP analysis for that area.
---------------------------------------------------------------------------

    \90\ North Dakota's 2022 SIP submission, appendix C.3-7.
---------------------------------------------------------------------------

    The data in WRAP's TSS indicate that North Dakota sources are 
reasonably anticipated to impact Voyageurs National Park. The EPA used 
WRAP's State Source Group Contributions to US Anthropogenic Impairment 
tool for Voyageurs National Park to analyze North Dakota sources' 
contribution to visibility impairment in that area. In terms of both 
ammonium sulfate extinction (0.55 Mm-1) and ammonium nitrate 
extinction (0.57 Mm-1), North Dakota had a greater impact on 
visibility impairment than any other WRAP state.\91\
---------------------------------------------------------------------------

    \91\ ``TSS XY Chart--Product #XMTP_SASB_LUCS.'' WRAP Technical 
Support System (TSS); CSU and the Cooperative Institute for Research 
in the Atmosphere (CIRA), 04 Dec 2023. WRAP states include Alaska, 
Arizona, California, Colorado, Hawaii, Idaho, Montana, Nevada, New 
Mexico, North Dakota, Oregon, South Dakota, Utah, Washington, and 
Wyoming.
---------------------------------------------------------------------------

    Further, Minnesota performed modeling in its 2022 SIP submission to 
assess contributions to visibility impairment in its two Class I areas: 
Voyageurs National Park and Boundary Waters Canoe Area Wilderness. This 
modeling showed that North Dakota contributed 5.9% of the total 
visibility impairment at Voyageurs National Park and 4.8% of the total 
visibility impairment at Boundary Waters Canoe Area Wilderness.\92\ 
These contributions are higher than any other state besides Minnesota. 
According to Minnesota's 2022 SIP submission, Minnesota began state-to-
state consultation with North Dakota in March 2021, and informed North 
Dakota about its potential contributions to Minnesota Class I areas in 
June 2022, prior to when North Dakota submitted its 2022 SIP 
submission.\93\ And again, even with all this data, North Dakota did 
not consider impacts on Voyagers National Park and Boundary Waters 
Canoe Area Wilderness when it rejected controls for Coyote Station and 
Antelope Valley, following four-factor analysis, on the basis that the 
associated visibility benefits at Class I areas were not significant 
enough to justify requiring those controls in its long-term strategy.
---------------------------------------------------------------------------

    \92\ Minnesota's 2022 SIP submission, 31.
    \93\ Id. at 144.
---------------------------------------------------------------------------

    In sum, data from the WEP analysis, WRAP's TSS, and visibility 
modeling performed by Minnesota indicate that

[[Page 56709]]

North Dakota sources are reasonably anticipated to cause or contribute 
to visibility impairment at out-of-state Class I areas including 
Medicine Lake Wilderness Area, Badlands National Park, Voyageurs 
National Park, and Boundary Waters Canoe Area Wilderness. When it 
considered the visibility improvements associated with the potential 
emission controls it evaluated through four-factor analysis, however, 
North Dakota only considered visibility impacts at in-state Class I 
areas. Thus, the visibility improvement values that North Dakota 
characterized as insignificant did not reflect potential improvements 
at any affected out-of-state Class I areas. As a result, North Dakota's 
evaluation of visibility improvements and its subsequent conclusion 
that emission controls at Coyote Station and Antelope Valley are not 
necessary to make reasonable progress at Class I areas are not 
adequately supported on the record.
ii. Projections That North Dakota Class I Areas Will Meet the Adjusted 
Uniform Rate of Progress Is Not a Sufficient Basis To Reject Controls 
Under 40 CFR 51.308(f)(2)(i)
    In rejecting controls it evaluated for Coyote Station and Antelope 
Valley through four-factor analysis, North Dakota also reasoned that 
Lostwood Wilderness Area and Theodore Roosevelt National Park were 
projected to achieve the adjusted URP by 2028.\94\ As the EPA has 
consistently explained, it is not appropriate for states to use the URP 
as a ``safe harbor'' to conclude that additional controls, including 
potentially cost-effective and otherwise reasonable controls, are not 
necessary for reasonable progress on the basis that Class I areas are 
below their URPs. The 2017 RHR explains:
---------------------------------------------------------------------------

    \94\ North Dakota's 2022 SIP submission, 100, 102.
---------------------------------------------------------------------------

    The CAA requires that each SIP revision contain long-term 
strategies for making reasonable progress, and that in determining 
reasonable progress states must consider the four statutory factors. 
Treating the URP as a safe harbor would be inconsistent with the 
statutory requirement that states assess the potential to make further 
reasonable progress towards [the] natural visibility goal in every 
implementation period. Even if a state is currently on or below the 
URP, there may be sources contributing to visibility impairment for 
which it would be reasonable to apply additional control measures in 
light of the four factors. Although it may conversely be the case that 
no such sources or control measures exist in a particular state with 
respect to a particular Class I area and implementation period, this 
should be determined based on a four-factor analysis for a reasonable 
set of in-state sources that are contributing the most to the 
visibility impairment that is still occurring at the Class I area. It 
would bypass the four statutory factors and undermine the fundamental 
structure and purpose of the reasonable progress analysis to treat the 
URP as a safe harbor, or as a rigid requirement.\95\
---------------------------------------------------------------------------

    \95\ 82 FR at 3099-3100.
---------------------------------------------------------------------------

    The EPA reiterated this concept in the 2019 Guidance \96\ and in 
the 2021 Clarifications Memo.\97\ Treating the URP as safe harbor is 
inconsistent with statutory requirements and undermines the core 
structure of a proper regional haze analysis.
---------------------------------------------------------------------------

    \96\ 2019 Guidance at 50.
    \97\ 2021 Clarifications Memo at 15-16.
---------------------------------------------------------------------------

    Notably, the CAA and RHR do not include the URP among the four 
statutory factors states must consider in developing their long-term 
strategies. North Dakota relied on this consideration to reject 
controls that its four-factor analysis did not show to be unreasonable. 
Thus, North Dakota's conclusion that no new controls are necessary 
(whether in whole or in part) because the State's Class I areas are 
below the adjusted URP is inconsistent with the plain text of the CAA 
and RHR.
b. Failure To Consider the Four Factors at Coal Creek and Unreasonable 
Rejection of Controls at Coal Creek and Leland Olds
    Coal Creek is a two-unit mine-mouth power plant located in McLean 
County, North Dakota with a capacity to produce approximately 1,200 
gross MW per hour of electricity. For the second implementation period, 
North Dakota did not perform a separate four-factor analysis for 
NOX controls at Coal Creek, pointing to its first planning 
period NOX BART determination for Coal Creek to satisfy 
reasonable progress for NOX.\98\ The 2017 RHR Revisions 
clarified that, as specified in CAA section 169A(g)(1), reasonable 
progress must be determined by applying the four statutory factors 
(costs of compliance, time necessary for compliance, energy and nonair 
quality environmental impacts of compliance, and remaining useful life 
of the source): ``The CAA requires that each SIP revision contain long-
term strategies for making reasonable progress, and that in determining 
reasonable progress states must consider the four statutory factors.'' 
\99\ Here, North Dakota used a five-factor BART analysis performed for 
the first planning period in an attempt to satisfy the requirement to 
consider the four statutory factors under reasonable progress in the 
second planning period. Though there is some overlap between the four 
factors considered under reasonable progress and the five factors 
considered under BART,\100\ North Dakota's analysis failed to consider 
one of the four factors under reasonable progress: time necessary for 
compliance. North Dakota failed to satisfy a core statutory requirement 
by not considering each of the four statutory factors in its reasonable 
progress analysis focused on NOX for Coal Creek.
---------------------------------------------------------------------------

    \98\ North Dakota's 2022 SIP submission, 103, 144.
    \99\ 82 FR at 3099; see also CAA 169A(b)(2)(B), (g)(1).
    \100\ CAA 169A(g)(1)-(2); 40 CFR 51.308(e)(1)(ii)(A), 
51.308(f)(2)(i). Under CAA 169A(g)(2), the five BART factors are 
costs of compliance, the energy and nonair quality environmental 
impacts of compliance, any existing pollution control technology in 
use at the source, the remaining useful life of the source, and the 
degree of improvement in visibility which may reasonably be 
anticipated to result from the use of such technology.
---------------------------------------------------------------------------

    Further, as we explained in the 2021 Clarifications Memo, a state 
that is relying on a source's existing effective controls to avoid 
performing a four-factor analysis should explain why an analysis 
``would not result in new controls and would, therefore, be a futile 
exercise.'' \101\ Here, however, in its BART five-factor analysis for 
Coal Creek Units 1 and 2 (which the EPA is not acting on in this 
proposed rulemaking), North Dakota evaluated more stringent control 
technologies (SNCR and SCR) beyond what North Dakota selected for BART. 
It stated that the average cost-effectiveness of SNCR at $3,300/ton 
appeared reasonable, but ultimately concluded that the incremental 
costs were high enough to warrant selection of a less stringent cost-
effective technology.\102\ Thus, it is clear that additional, more 
stringent NOX controls for Coal Creek exist, and should be 
evaluated under the four statutory factors for the purpose of 
determining the measures necessary to make reasonable progress for the 
second implementation period.
---------------------------------------------------------------------------

    \101\ 2021 Clarifications Memo at 5; see also 2019 Guidance at 
22 (explaining that the reason underlying this flexibility is the 
low likelihood of a significant technological advancement that could 
provide further reasonable emission reductions).
    \102\ North Dakota's 2022 SIP submission, appendix F.1-5-F.1-8, 
F.1-14-F.1-15.
---------------------------------------------------------------------------

    We also find that North Dakota unreasonably rejected emission 
reduction measures at Coal Creek and Leland Olds. In its four-factor 
analysis of Coal Creek Units 1 and 2 for reasonable progress for 
SO2, North Dakota evaluated two different controls: a new 
wetstack and a natural gas reheat

[[Page 56710]]

system. North Dakota's cost effectiveness evaluation of the new 
wetstack resulted in an estimated cost of $2,890/ton of SO2 
removed, while evaluation of the natural gas reheat system resulted in 
an estimated cost of $2,460/ton of SO2 removed.\103\ In its 
four-factor analysis of Leland Olds Unit 2 (which currently operates 
SNCR and separated overfire air for NOX control as a result 
of the State's BART determination \104\), North Dakota's cost 
effectiveness evaluation of optimized SNCR resulted in an estimated 
cost of $3,582/ton of NOX removed.\105\ Each of these 
evaluated controls, both at Coal Creek and Leland Olds, are consistent 
with what the EPA has previously found to be cost-effective in prior 
regional haze rulemakings,\106\ and are otherwise reasonable when 
considering the other three statutory factors.\107\ Indeed, North 
Dakota did not determine the costs to be unreasonable.\108\ 
Nonetheless, North Dakota rejected these controls.
---------------------------------------------------------------------------

    \103\ Id., appendix A.4-4.
    \104\ North Dakota's 2022 SIP submission, appendix A.3-2-A.3-3; 
77 FR 20894, 20897 (April 6, 2012) (approving the State's 
NOX BART determination).
    \105\ Id., appendix A.3-8.
    \106\ These cost-effectiveness values are in line with those the 
EPA and states found reasonable for regional haze control measures 
adopted in the first planning period, even without adjusting for 
inflation. After evaluating first planning period cost of compliance 
values, plus the other BART statutory factors and/or the four 
reasonable progress statutory factors, states and the EPA found 
numerous instances of cost-effectiveness values up to and sometimes 
higher than $4,500/ton to be reasonable and cost effective. This 
includes control determinations for sources within North Dakota and 
in other states. Examples for several sources can be found at: 76 FR 
16168, 16181 (Mar. 22, 2011) (proposed), finalized at 76 FR 81728 
(Dec. 28, 2011) (Oklahoma); 76 FR 58570, 58587-88 (Sept. 21, 2011) 
(proposed), finalized at 77 FR 20894 (Apr. 6, 2012) (North Dakota); 
77 FR 11022, 11033-34 (Feb. 24, 2012) (proposed), finalized at 78 FR 
10546 (Feb. 14, 2013) (Alaska); and 79 FR 5032, 5039 (Jan. 30, 2014) 
(Wyoming) (final rule). The cited costs have not been adjusted for 
inflation.
    \107\ In its consideration of the three non-cost statutory 
factors, North Dakota did not identify any barriers that would 
render these controls unreasonable. North Dakota's 2022 SIP 
submission, appendix A.3-8-A.3-9 (Leland Olds), appendix A.4.4-A.4.5 
(Coal Creek).
    \108\ North Dakota's 2022 SIP submission, 103-04, appendix A.3-
8, A.4-4.
---------------------------------------------------------------------------

    North Dakota did not explain why it declined to require a new wet 
stack or natural gas reheat system at Coal Creek Units 1 and 2. Neither 
the four-factor analysis in appendix A.4 nor the narrative discussion 
in section 5.2.4 of North Dakota's 2022 SIP submission provide any 
insight into the State's reasoning.\109\ Therefore, we cannot conclude 
that North Dakota's rejection of these controls was justified under the 
CAA and RHR.
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    \109\ While North Dakota stated that future operations and 
SO2 emissions at Coal Creek are expected to remain 
consistent with current conditions, the State did not identify these 
future conditions as a reason for its rejection of the controls 
evaluated through four-factor analysis. Id. at 104.
---------------------------------------------------------------------------

    As for Leland Olds Unit 2, North Dakota offered the following 
reasoning for its determination not to require optimized SNCR or other 
NOX controls for the second implementation period: ``[F]our-
factor analysis confirmed that these [existing] BART controls operate 
effectively, and the Department has no reason to believe effective 
operation of the BART controls will change in the future. Therefore, no 
additional measures were selected for the modeling evaluation and the 
Department does not believe additional controls are warranted during 
this planning period.'' \110\ The presence of BART controls, however, 
does not exempt sources from installing additional reasonable controls 
that are shown to be necessary, through four-factor analysis, to make 
reasonable progress during the second planning period.\111\ We 
explained that principle in the 2021 Clarifications Memo: ``A state 
relying on an `effective control' to avoid performing a four-factor 
analysis for a source should demonstrate why, for that source 
specifically, a four-factor analysis would not result in new controls 
and would, therefore, be a futile exercise.'' \112\ Here, North Dakota 
conducted a four-factor analysis of NOX controls at Leland 
Olds Unit 2, which identified optimized SNCR as a cost-effective and 
otherwise reasonable new control. But North Dakota then concluded, 
without providing any justification grounded in the CAA or RHR, that 
because the source still operates and will continue to operate BART 
controls, any additional controls are not warranted. Here, North 
Dakota's analysis identified a cost-effective potential NOX 
control, but the State did not reasonably explain why it declined to 
require that control because, as described in the preceding paragraphs, 
it improperly relied on the presence of BART controls and did not 
properly consider the four statutory factors.
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    \110\ Id. at 103.
    \111\ 40 CFR 51.308(e)(5) states that ``[a]fter a State has met 
the requirements for BART or implemented an emissions trading 
program or other alternative measure that achieves more reasonable 
progress than the installation and operation of BART, BART-eligible 
sources will be subject to the requirements of paragraphs (d) and 
(f) of this section.''
    \112\ 2021 Clarifications Memo at 5.
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2. Other Long-Term Strategy Requirements Under 40 CFR 51.308(f)(2)(ii)-
(iv)
    States must meet the additional requirements specified in 40 CFR 
51.308(f)(2)(ii)-(iv) when developing their long-term strategies. 40 
CFR 51.308(f)(2)(ii) requires states to consult with other states that 
have emissions that are reasonably anticipated to contribute to 
visibility impairment in Class I areas to develop coordinated emission 
management strategies. North Dakota engaged with other states 
throughout the development of its 2022 SIP submission by participating 
in WRAP regional haze workgroup meetings. Additionally, North Dakota 
directly communicated with other states about the SIP submission, 
including South Dakota, Montana, and Minnesota.\113\
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    \113\ Id. at 33-34, appendix E.2.
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    40 CFR 51.308(f)(2)(iii) requires states to document the technical 
basis, including modeling, monitoring, costs, engineering, and 
emissions information, on which the state is relying to determine the 
emission reduction measures that are necessary to make reasonable 
progress in each mandatory Class I area it impacts. Section 4.1 of 
North Dakota's 2022 SIP submission describes the emissions inventories 
and projections the State used in its analysis.
    40 CFR 51.308(f)(2)(iv) specifies five additional factors states 
must consider in developing their long-term strategies. The five 
additional factors are: emission reductions due to ongoing air 
pollution control programs, including measures to address reasonably 
attributable visibility impairment; measures to mitigate the impacts of 
construction activities; source retirement and replacement schedules; 
basic smoke management practices for prescribed fire used for 
agricultural and wildland vegetation management purposes and smoke 
management programs; and the anticipated net effect on visibility due 
to projected changes in point, area, and mobile source emissions over 
the period addressed by the long-term strategy. North Dakota described 
each of the five additional factors in section 5.3 of its 2022 SIP 
submission.
    Regardless, as explained in the preceding sections, due to flaws 
and omissions in its four-factor analyses and the resulting control 
determinations, the EPA finds that North Dakota failed to submit to the 
EPA a long-term strategy that includes ``the enforceable emissions 
limitations, compliance schedules, and other measures that are 
necessary to make reasonable progress'' as required by 40 CFR 
51.308(f)(2).\114\ Consequently,

[[Page 56711]]

we find that North Dakota's 2022 SIP Submission does not satisfy the 
long-term strategy requirements of 40 CFR 51.308(f)(2). Therefore, the 
EPA proposes to disapprove all elements of North Dakota's 2022 SIP 
submission as it relates to 51.308(f)(2)'s long-term strategy 
requirements.
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    \114\ See also CAA 169A(b)(2), 169A(b)(2)(B) (requiring regional 
haze SIPs to ``contain such emission limits, schedules of compliance 
and other measures as may be necessary to make reasonable progress 
toward meeting the national goal, . . . including . . . a long-term 
. . . strategy for making reasonable progress[.]'').
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C. Reasonable Progress Goals

    The EPA proposes to find that North Dakota did not meet the 
reasonable progress goal requirements under 40 CFR 51.308(f)(3). 
Section 51.308(f)(3)(i) requires a state in which a Class I area is 
located to establish RPGs--one each for the most impaired and clearest 
days--reflecting the visibility conditions that will be achieved at the 
end of the implementation period as a result of the emission 
limitations, compliance schedules and other measures required under 
paragraph (f)(2) in states' long-term strategies, as well as 
implementation of other CAA requirements.
    After establishing its long-term strategy, North Dakota developed 
reasonable progress goals for each Class I area for the 20% most 
impaired days and 20% clearest days based on the results of 2028 WRAP 
modeling.\115\ The reasonable progress goals are based on North 
Dakota's long-term strategy, the long-term strategy of other states 
that may affect Class I areas in North Dakota, and other CAA 
requirements.
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    \115\ North Dakota's 2022 SIP Submission, section 6.
---------------------------------------------------------------------------

    Per 40 CFR 51.308(f)(3)(iv), the EPA must evaluate the 
demonstrations the State developed pursuant to 40 CFR 51.308(f)(2) to 
determine whether the State's reasonable progress goals for visibility 
improvement provide for reasonable progress towards natural visibility 
conditions. As previously explained in section IV.B., we are proposing 
to disapprove North Dakota's long-term strategy for failing to meet the 
requirements of 40 CFR 51.308(f)(2).\173\ Therefore, we also propose to 
disapprove North Dakota's reasonable progress goals under 40 CFR 
51.308(f)(3) because compliance with that requirement is dependent on 
compliance with 40 CFR 51.308(f)(2).

D. Reasonably Attributable Visibility Impairment (RAVI)

    The RHR contains a requirement at Sec.  51.308(f)(4) related to any 
additional monitoring that may be needed to address visibility 
impairment in Class I areas from a single source or a small group of 
sources. This is called ``reasonably attributable visibility 
impairment,'' \116\ also known as RAVI. Under this provision, if the 
EPA or the FLM of an affected Class I area has advised a state that 
additional monitoring is needed to assess RAVI, the state must include 
in its SIP revision for the second implementation period an appropriate 
strategy for evaluating such impairment. The EPA has not advised North 
Dakota to that effect, and the FLMs for the Class I areas that North 
Dakota contributes to have not identified any RAVI from North Dakota 
sources.\117\ For this reason, the EPA proposes to approve the portions 
of North Dakota's 2022 SIP submission relating to 40 CFR 51.308(f)(4).
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    \116\ The EPA's visibility protection regulations define 
``reasonably attributable visibility impairment'' as ``visibility 
impairment that is caused by the emission of air pollutants from 
one, or a small number of sources.'' 40 CFR 51.301.
    \117\ North Dakota's 2022 SIP submission, 139.
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E. Monitoring Strategy and Other Implementation Plan Requirements

    Section 51.308(f)(6) specifies that each comprehensive revision of 
a state's regional haze SIP must contain or provide for certain 
elements, including monitoring strategies, emissions inventories, and 
any reporting, recordkeeping and other measures needed to assess and 
report on visibility. A main requirement of this section is for states 
with Class I areas to submit monitoring strategies for measuring, 
characterizing, and reporting on visibility impairment. Compliance with 
this requirement may be met through participation in the Interagency 
Monitoring of Protected Visual Environments (IMPROVE) network. North 
Dakota participates in the IMPROVE network.
    Section 51.308(f)(6)(i) requires SIPs to provide for the 
establishment of any additional monitoring sites or equipment needed to 
assess whether reasonable progress goals to address regional haze for 
all mandatory Class I Federal areas within the state are being 
achieved. As noted in the 2017 RHR Revisions, ``neither the EPA nor any 
state has concluded that the IMPROVE network is not sufficient in this 
way.'' \118\ Regional haze data for Theodore Roosevelt National Park 
and Lostwood Wilderness Area are collected by IMPROVE monitors that are 
operated and maintained by the NPS and the USFWS, respectively. The EPA 
is not aware of information suggesting that those IMPROVE monitors are 
no longer sufficient to assess the status of reasonable progress goals 
at those Class I areas. Therefore, the EPA finds that North Dakota has 
satisfied Sec.  51.308(f)(6)(i).
---------------------------------------------------------------------------

    \118\ 82 FR at 3085.
---------------------------------------------------------------------------

    Section 51.308(f)(6)(ii) requires SIPs to provide for procedures by 
which monitoring data and other information are used in determining the 
contribution of emissions from within the state to regional haze 
visibility impairment at mandatory Class I Federal areas both within 
and outside the state. For the second implementation period, WRAP 
performed technical analyses to help assess source and state-level 
contributions to visibility impairment.\119\ North Dakota relied on 
these source-apportionment analyses to determine the contribution of 
emissions from within the State to visibility impairment in Class I 
areas outside the State.\120\ As explained in section IV.B.1.a. of this 
document, the record does not support North Dakota's determination that 
its sources are not reasonably anticipated to impact out-of-state Class 
I areas; instead, the technical data the State relied on, including 
WRAP data, indicate the opposite. Regardless of the State's 
interpretation of that data, because the 2022 SIP submission relies on 
WRAP technical data and provides for procedures to determine in-state 
contributions to visibility impairment, we find that North Dakota has 
satisfied Sec.  51.308(f)(6)(ii) by relying on WRAP's source-
apportionment analyses.
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    \119\ WRAP Technical Support System (TSS); CSU and the 
Cooperative Institute for Research in the Atmosphere (CIRA), 09 Oct 
2023, https://views.cira.colostate.edu/tssv2.
    \120\ North Dakota's 2022 SIP submission, 39.
---------------------------------------------------------------------------

    Section 51.308(f)(6)(iii) does not apply to North Dakota, as it has 
Class I areas. Section 51.308(f)(6)(iv) requires the SIP to provide for 
the reporting of all visibility monitoring data to the Administrator at 
least annually for each Class I area in the state. North Dakota's 
monitoring strategy relies upon the continued availability of the 
IMPROVE network, whose monitors are operated and maintained by the NPS 
and the USFWS. The IMPROVE Steering committee and Data Analysis and 
Reporting subcommittee develop policies to generate and distribute 
IMPROVE data, metadata, and data products. The data is made available 
on IMPROVE, FLM, and the EPA Air Quality System databases. North Dakota 
supports the continued operation of the IMPROVE network through state 
funding mechanisms. We find that North Dakota has satisfied Sec.  
51.308(f)(6)(iv).
    Section 51.308(f)(6)(v) requires SIPs to provide for a statewide 
inventory of emissions of pollutants that are

[[Page 56712]]

reasonably anticipated to cause or contribute to visibility impairment, 
including emissions for the most recent year for which data are 
available. North Dakota provides for emissions inventories and 
estimates of future projected emissions by participating in WRAP and by 
complying with the EPA's Air Emissions Reporting Rule (AERR). In 40 CFR 
part 51, subpart A, the AERR requires states to submit updated 
emissions inventories for criteria pollutants to the EPA's Emission 
Inventory System (EIS) annually or triennially depending on the source 
type. The EPA uses the inventory data from the EIS to develop the NEI, 
which is a comprehensive estimate of air emissions of criteria 
pollutants, criteria precursors, and hazardous air pollutants from air 
emissions sources. The EPA releases an NEI every three years.
    Section 4 of North Dakota's 2022 SIP submission includes tables of 
NEI data. The source categories of the emissions inventories include 
point sources, area and non-point sources, non-road mobile sources, on-
road mobile sources, natural sources, and international anthropogenic 
emissions. The inventories account for emissions of SO2, 
NOX, PM10, PM2.5, VOC, and 
NH3 in 2002 (one of the regional haze program baseline 
years), 2011, 2014, and 2017.
    Section 51.308(f)(6)(v) also requires states to include estimates 
of future projected emissions. North Dakota used three different 
modeling scenarios in WRAP modeling, which produced a range of future 
projected emissions for 2028.\121\
---------------------------------------------------------------------------

    \121\ North Dakota's 2022 SIP submission, 66-68, 140.
---------------------------------------------------------------------------

    The EPA finds that North Dakota has met the requirements of 40 CFR 
51.308(f)(6)(v) through its ongoing compliance with the AERR, its 
compilation of a statewide emissions inventory based on NEI data, its 
use of WRAP modeling to project future emissions, and its commitment to 
update its inventory periodically.\122\
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    \122\ Id. at 140.
---------------------------------------------------------------------------

    Finally, Sec.  51.308(f)(6)(vi) requires the SIP to provide for any 
other elements, including reporting, recordkeeping, and other measures, 
that are necessary for states to assess and report on visibility. North 
Dakota assesses and reports on visibility through participation in the 
IMPROVE network. The EPA finds that North Dakota has satisfied the 
requirements of 40 CFR 51.308(f)(6)(vi) and that no further elements 
are necessary at this time for North Dakota to assess and report on 
visibility.
    In sum, for all the reasons discussed in this section IV.E., the 
EPA is proposing to approve North Dakota's 2022 submission as meeting 
the requirements of 40 CFR 51.308(f)(6).

F. Requirements for Periodic Reports Describing Progress Towards the 
Reasonable Progress Goals

    40 CFR 51.308(f)(5) requires that periodic comprehensive revisions 
of states' regional haze plans also address the progress report 
requirements of 40 CFR 51.308(g)(1) through (5). The purpose of these 
requirements is to evaluate progress towards the applicable RPGs for 
each Class I area within the state and each Class I area outside the 
state that may be affected by emissions from within that state. 
Sections 51.308(g)(1) and (2) apply to all states and require a 
description of the status of implementation of all measures included in 
a state's first implementation period regional haze plan and a summary 
of the emission reductions achieved through implementation of those 
measures. Section 51.308(g)(3) applies only to states with Class I 
areas within their borders and requires such states to assess current 
visibility conditions, changes in visibility relative to baseline 
(2000-2004) visibility conditions, and changes in visibility conditions 
relative to the period addressed in the first implementation period 
progress report. Section 51.308(g)(4) applies to all states and 
requires an analysis tracking changes in emissions of pollutants 
contributing to visibility impairment from all sources and sectors 
since the period addressed by the first implementation period progress 
report. This provision further specifies the year or years through 
which the analysis must extend depending on the type of source and the 
platform through which its emission information is reported. Finally, 
Sec.  51.308(g)(5), which also applies to all states, requires an 
assessment of any significant changes in anthropogenic emissions within 
or outside the state that have occurred since the period addressed by 
the first implementation period progress report, including whether such 
changes were anticipated and whether they have limited or impeded 
expected progress towards reducing emissions and improving visibility.
    Section 9 of North Dakota's 2022 SIP submission describes the 
status of the long-term strategy measures from the first implementation 
period. The State's regional haze SIP submission for the first 
implementation period relied primarily on SO2 and 
NOX reductions from existing coal-fired EGUs. The 
requirements for those reductions were based on both the BART 
requirements in 40 CFR 51.308(e) and the reasonable progress 
requirements in 40 CFR 51.308(d). Additional control measures that 
North Dakota relied on to meet the requirements under the first 
implementation period are described in section 5.3.1 of North Dakota's 
2022 SIP submission. North Dakota's BART limits from the first planning 
period SIP submission have been incorporated into the State's permits 
for the affected sources, except for Coal Creek Station NOX 
BART.\123\ All EGUs with BART controls from the first planning period 
have associated limits at 40 CFR 52.1820(d).
---------------------------------------------------------------------------

    \123\ Coal Creek Station Unit 1 and 2 NOX BART limits 
are addressed in section 8 and appendix F of North Dakota's 2022 SIP 
submission.
---------------------------------------------------------------------------

    North Dakota states that since the baseline period of 2000-2004, 
there have been significant reductions of most visibility impairing 
pollutants in North Dakota that can be attributed to the point and 
mobile source categories.\124\ The State attributes the implementation 
of new controls at coal-fired EGUs and new federal requirements for on- 
and off-road engines as the main reasons for the reductions. Sections 
4.1.1, 4.1.2, and 4.1.5 contain emission inventories for WRAP's 2002 
Plan 02d and the 2011 and 2017 National Emissions Inventory (NEI). As 
evidence of overall emission reductions at the EGUs, North Dakota 
points to Table 20 in section 4.2.1, which shows the emissions of 
visibility impairing pollutants from North Dakota's coal-fired EGUs for 
each inventory year. SO2 and NOX reductions from 
individual coal-fired EGUs are listed in sections 4.2.1.1.1 and 
4.2.1.1.2. The EPA finds that North Dakota has met the requirements of 
40 CFR 51.308(g)(1) and (2) by describing the measures included in the 
long-term strategy from the first implementation period, as well as the 
status of their implementation and the emission reductions achieved 
through such implementation.
---------------------------------------------------------------------------

    \124\ North Dakota's 2022 SIP submission, 150.
---------------------------------------------------------------------------

    Section 3 summarizes the visibility conditions and the trend of the 
5-year averages through 2017 at Theodore Roosevelt National Park and 
Lostwood Wilderness Area. Section 3.2.1 describes the 5-year baseline 
(2000-2004) visibility conditions for the clearest and most impaired 
days, while section 3.2.3 sets out the current 5-year rolling average 
(2014-2018) for the clearest and most impaired days. Table 9 in section 
3.2.4 identifies the progress to date for the clearest and most 
impaired days, showing data from 2008-2012 as

[[Page 56713]]

representative of the first implementation period.
    Section 4.1 summarizes emissions of NOX, SO2, 
PM10, PM2.5, VOC, and NH3 from all 
sources and activities, including from point, nonpoint, non-road 
mobile, and on-road mobile sources, for 2002, 2011, 2014, 2017, current 
representative, and projected future emissions. Comparing the 2002 and 
2017 emissions inventories shows that emissions of SO2, 
NOX, and NH3 decreased, while emissions of VOC, 
PM2.5, and PM10 increased. Comparing the 2002 and 
RepBase (current representative) emissions inventories shows that 
emissions of SO2, NH3, PM2.5, and 
PM10 decreased, while emissions of NOX and VOC 
increased.\125\
---------------------------------------------------------------------------

    \125\ Section 9.3.5 of North Dakota's 2022 SIP submission 
considers the potential impact of oil and gas development on the 
increase in anthropogenic emissions of NOX and VOC.
---------------------------------------------------------------------------

    Section 9.3.5 assesses changes in anthropogenic emissions impeding 
visibility progress. Regarding NOX, North Dakota concluded 
that total anthropogenic NOX emissions have not changed 
significantly in the RepBase (current representative) emissions 
inventory compared to 2002.
    In sum, because North Dakota's 2022 SIP submission addresses the 
requirements of 40 CFR 51.308(g)(1) through (5), the EPA is proposing 
to approve Section 9 of North Dakota's 2022 SIP submission as meeting 
the requirements of 40 CFR 51.308(f)(5) and 40 CFR 51.308(g) for 
periodic progress reports.

G. Requirements for Federal Land Manager Coordination

    Section 169A(d) of the CAA requires states to consult with FLMs 
before holding the public hearing on a proposed regional haze SIP, and 
to include a summary of the FLMs' conclusions and recommendations in 
the notice to the public. In addition, the 40 CFR 51.308(i)(2) FLM 
consultation provision requires a state to provide FLMs with an 
opportunity for consultation that is early enough in the state's policy 
analyses of its emission reduction obligation so that information and 
recommendations provided by the FLMs can meaningfully inform the 
state's decisions on its long-term strategy. If the consultation has 
taken place at least 120 days before a public hearing or public comment 
period, the opportunity for consultation will be deemed early enough. 
Regardless, the opportunity for consultation must be provided at least 
sixty days before a public hearing or public comment period at the 
state level. Section 51.308(i)(2) also lists two substantive topics on 
which FLMs must be provided an opportunity to discuss with states: 
assessment of visibility impairment in any Class I area and 
recommendations on the development and implementation of strategies to 
address visibility impairment. Section 51.308(i)(3) requires states, in 
developing their implementation plans, to include a description of how 
they addressed FLMs' comments.
    North Dakota's 2022 SIP submission summarizes the State's 
consultation and coordination with the FLMs. North Dakota engaged with 
FLMs early in the planning process by participating in WRAP meetings 
and by holding separate calls with FLMs to discuss visibility 
impairment in Class I areas and the State's plans for its 2022 SIP 
submission. North Dakota also met via video conference with the NPS on 
November 6, 2020, and December 15, 2020, and with the USFS on November 
23, 2020. Upon completing its draft 2022 SIP submission, North Dakota 
provided it to FLMs for a review and consultation period from September 
20, 2021, through November 19, 2021. Additionally, North Dakota held a 
video conference with the NPS, USFS, and EPA Region 8 staff on November 
10, 2021, to discuss the draft and receive feedback from the FLMs. 
North Dakota received comments from USFS on November 17, 2021, and from 
the NPS on November 19, 2021.\126\ North Dakota responded to the FLM 
comments and included the responses in appendix D of its 2022 SIP 
submission.
---------------------------------------------------------------------------

    \126\ The USFWS did not comment on North Dakota's 2022 SIP 
submission.
---------------------------------------------------------------------------

    Compliance with 40 CFR 51.308(i) is dependent on compliance with 40 
CFR 51.308(f)(2)'s long-term strategy provisions and (f)(3)'s 
reasonable progress goals provisions. Because the EPA is proposing to 
disapprove North Dakota's long-term strategy under 51.308(f)(2) and the 
reasonable progress goals under 51.308(f)(3), the EPA is also proposing 
to disapprove the State's FLM consultation under 51.308(i). While North 
Dakota did take administrative steps to provide the FLMs the 
opportunity to review and provide feedback on the State's draft 
regional haze plan, the EPA cannot approve that consultation because it 
was based on a plan that does not meet the statutory and regulatory 
requirements of the CAA and the RHR, as described in this notice of 
proposed rulemaking. In addition, if the EPA finalizes our proposed 
partial approval and partial disapproval of North Dakota's SIP 
submission, the State (or the EPA in the potential case of a FIP) will 
be required to again complete the FLM consultation requirements under 
40 CFR 51.308(i). Therefore, the EPA proposes to disapprove the FLM 
consultation component of North Dakota's SIP submission for failure to 
meet the requirements of 40 CFR 51.308(i), as outlined in this section.

V. Proposed Action

    The EPA is proposing approval of the portions of North Dakota's 
2022 SIP submission relating to 40 CFR 51.308(f)(1): calculations of 
baseline, current, and natural visibility conditions, progress to date, 
and the uniform rate of progress; 40 CFR 51.308(f)(4): reasonably 
attributable visibility impairment; 40 CFR 51.308(f)(5) and 40 CFR 
51.308(g): progress report requirements; and 40 CFR 51.308(f)(6): 
monitoring strategy and other implementation plan requirements. The EPA 
is proposing disapproval of the remainder of North Dakota's 2022 SIP 
submission, which addresses 40 CFR 51.308(f)(2): long-term strategy; 40 
CFR 51.308 (f)(3): reasonable progress goals; and 40 CFR 51.308(i): FLM 
consultation.

VI. Environmental Justice

    The EPA conducted an environmental justice (EJ) screening analysis 
around the location of the facilities associated with North Dakota's 
2022 SIP submission to identify potential environmental stressors on 
these communities. The EPA is providing the information associated with 
this analysis for informational purposes only; it does not form any 
part of the basis of this proposed action.
    The EPA conducted the screening analyses using EJScreen, an 
environmental justice mapping and screening tool that provides the EPA 
with a nationally consistent dataset and approach for combining various 
environmental and demographic indicators.\127\ The EPA prepared 
EJScreen reports covering buffer areas of approximately six miles 
around the ten facilities selected for four-factor analysis in North 
Dakota's 2022 SIP submission. From those reports, no facilities showed 
environmental justice indices greater than the 80th national 
percentiles.\128\

[[Page 56714]]

The full, detailed EJScreen reports are provided in the docket for this 
rulemaking.
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    \127\ The EJSCREEN tool is available at https://www.epa.gov/ejscreen.
    \128\ This means that 20 percent of the U.S. population has a 
higher value. The EPA identified the 80th percentile filter as an 
initial starting point for interpreting EJScreen results. The use of 
an initial filter promotes consistency for the EPA's programs and 
regions when interpreting screening results.
---------------------------------------------------------------------------

VII. Statutory and Executive Order Reviews

    Under the CAA, the Administrator is required to approve a SIP 
submission that complies with the provisions of the Act and applicable 
Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in 
reviewing SIP submissions, the EPA's role is to approve state choices, 
provided that they meet the criteria of the CAA. Accordingly, this 
action merely proposes to approve state law as meeting Federal 
requirements and does not impose additional requirements beyond those 
imposed by state law. For that reason, this action:
     Is not a ``significant regulatory action'' subject to 
review by the Office of Management and Budget under Executive Orders 
12866 (58 FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 
2011);
     Does not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or 
uniquely affect small governments, as described in the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4);
     Does not have Federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not an economically significant regulatory action based 
on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);
     Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001);
     Is not subject to requirements of section 12(d) of the 
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 
note) because application of those requirements would be inconsistent 
with the CAA; and
    In addition, the SIP is not approved to apply on any Indian 
reservation land or in any other area where the EPA or an Indian Tribe 
has demonstrated that a Tribe has jurisdiction. In those areas of 
Indian country, the proposed rule does not have tribal implications and 
will not impose substantial direct costs on tribal governments or 
preempt tribal law as specified by Executive Order 13175 (65 FR 67249, 
November 9, 2000).
    Executive Order 12898 (Federal Actions to Address Environmental 
Justice in Minority Populations and Low-Income Populations, 59 FR 7629, 
Feb. 16, 1994) directs federal agencies to identify and address 
disproportionately high and adverse human health or environmental 
effects of their actions on minority populations and low-income 
populations to the greatest extent practicable and permitted by law. 
The EPA defines environmental justice as the fair treatment and 
meaningful involvement of all people regardless of race, color, 
national origin, or income with respect to the development, 
implementation, and enforcement of environmental laws, regulations, and 
policies. The EPA further defines the term fair treatment to mean that 
no group of people should bear a disproportionate burden of 
environmental harms and risks, including those resulting from the 
negative environmental consequences of industrial, governmental, and 
commercial operations or programs and policies.
    North Dakota did not evaluate environmental justice considerations 
as part of its SIP submission; the CAA and applicable implementing 
regulations neither prohibit nor require such an evaluation. The EPA 
performed an environmental justice screening analysis, as described 
above in section VI. Environmental Justice. The analysis was done for 
the purpose of providing additional context and information about this 
rulemaking to the public, not as a basis of the action. There is no 
information in the record upon which this decision is based 
inconsistent with the stated goal of E.O. 12898 of achieving 
environmental justice for people of color, low-income populations, and 
Indigenous peoples.

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Carbon monoxide, 
Greenhouse gases, Incorporation by reference, Intergovernmental 
relations, Lead, Nitrogen dioxide, Ozone, Particulate matter, Reporting 
and recordkeeping requirements, Sulfur oxides, Volatile organic 
compounds.

    Authority: 42 U.S.C. 7401 et seq.

    Dated: June 27, 2024.
KC Becker,
Regional Administrator, Region 8.
[FR Doc. 2024-14761 Filed 7-9-24; 8:45 am]
BILLING CODE 6560-50-P