Proposed Rule2026-02843
Approval and Promulgation of Air Quality Implementation Plans; Oklahoma; Regional Haze State Implementation Plan for the Second Implementation Period
Primary source
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Published
February 12, 2026
Issuing agencies
Environmental Protection Agency
Abstract
The Environmental Protection Agency (EPA) is proposing to approve the regional haze state implementation plan (SIP) revision submitted by the State of Oklahoma on August 9, 2022 (Oklahoma's 2022 SIP submission), to satisfy applicable requirements under the Clean Air Act (CAA) and the EPA's Regional Haze Rule (RHR) for the program's second implementation (planning) period. Oklahoma's SIP submission addresses the requirement that states must periodically revise their long-term strategies for making 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. The 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.
Full Text
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<title>Federal Register, Volume 91 Issue 29 (Thursday, February 12, 2026)</title>
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[Federal Register Volume 91, Number 29 (Thursday, February 12, 2026)]
[Proposed Rules]
[Pages 6581-6603]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-02843]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52
[EPA-R06-OAR-2022-0736; FRL-9406-01-R6]
Approval and Promulgation of Air Quality Implementation Plans;
Oklahoma; 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
approve the regional haze state implementation plan (SIP) revision
submitted by the State of Oklahoma on August 9, 2022 (Oklahoma's 2022
SIP submission), to satisfy applicable requirements under the Clean Air
Act (CAA) and the EPA's Regional Haze Rule (RHR) for the program's
second implementation (planning) period. Oklahoma's SIP submission
addresses the requirement that states must periodically revise their
long-term strategies for making 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. The 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 March 16, 2026.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R06-
OAR-2022-0736 at <a href="https://www.regulations.gov">https://www.regulations.gov</a>. For comments submitted at
<a href="http://Regulations.gov">Regulations.gov</a>, follow the online instructions for submitting
comments. Once submitted, comments cannot be edited or removed from
<a href="http://Regulations.gov">Regulations.gov</a>. 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, please contact the person identified in
the FOR FURTHER INFORMATION CONTACT section. For the full EPA public
comment policy, information about CBI or multimedia submissions, and
general guidance on making effective comments, please visit <a href="https://www.epa.gov/dockets/commenting-epa-dockets">https://www.epa.gov/dockets/commenting-epa-dockets</a>.
Docket: The index to the docket for this action is available
electronically at <a href="http://www.regulations.gov">www.regulations.gov</a>. While all documents in the
docket are listed in the index, some information may not be publicly
available due to docket file size restrictions or content (e.g., CBI).
FOR FURTHER INFORMATION CONTACT: Karolina Ruan Lei, EPA Region 6
Office, Air and Radiation Division, Regional Haze and SO<INF>2</INF>
Section, 214-665-7346, <a href="/cdn-cgi/l/email-protection#5b292e3a3576373e3275303a29343732353a1b3e2b3a753c342d"><span class="__cf_email__" data-cfemail="106265717e3d7c75793e7b71627f7c797e71507560713e777f66">[email protected]</span></a>. We encourage the
public to submit comments via <a href="https://www.regulations.gov">https://www.regulations.gov</a>. Please call
or email the contact listed above if you need alternative access to
material indexed but not provided in the docket.
SUPPLEMENTARY INFORMATION:
Table of Contents
I. What action is the EPA proposing?
II. Background and Requirements for Regional Haze Plans
A. Regional Haze
B. Roles of Agencies in Addressing Regional Haze
C. Status of Oklahoma's Regional Haze Plan for the First
Implementation Period
D. Oklahoma's Regional Haze Plan for the Second Implementation
Period
III. Requirements for Regional Haze Plans for the Second
Implementation Period
A. Reasonable Progress Goals
B. Monitoring Strategy and Other State Implementation Plan
Requirements
C. Requirements for Periodic Reports Describing Progress Towards
the Reasonable Progress Goals
D. Requirements for State and Federal Land Manager Coordination
IV. The EPA's Evaluation of Oklahoma's Regional Haze Plan for the
Second Implementation Period
A. Identification of Class I Areas
B. Calculations of Baseline, Current, and Natural Visibility
Conditions; Progress to Date; and Uniform Rate of Progress for Class
I Areas Within the State
C. Long-Term Strategy
D. Reasonable Progress Goals
E. Reasonably Attributable Visibility Impairment
F. Monitoring Strategy and Other State Implementation Plan
Requirements
G. Requirements for Periodic Reports Describing Progress Towards
the Reasonable Progress Goals
H. Requirements for State and Federal Land Manager Coordination
V. Proposed Action
VI. Incorporation by Reference
VII. Impact on Areas of Indian Country
VIII. Statutory and Executive Order Reviews
I. What action is the EPA proposing?
On August 9, 2022, the Oklahoma Secretary of Energy and
Environment, the State of Oklahoma designee for submitting documents to
the EPA for approval and incorporation into the SIP, submitted a
revision to the Oklahoma SIP to address regional haze for the second
implementation period. Oklahoma made this SIP submission to satisfy the
requirements of the CAA's regional haze program pursuant to CAA
sections 169A and 169B and 40 CFR 51.308. The EPA is proposing to find
that the Oklahoma regional haze SIP submission for the second
implementation period meets the applicable statutory and regulatory
requirements and thus proposes to approve Oklahoma's submission into
its SIP. Specifically, the EPA is proposing to approve Oklahoma's 2022
SIP submission as satisfying the requirements of:
(1) 40 CFR 51.308(f)(1): calculations of baseline, current, and
natural visibility conditions, progress to date, and the uniform rate
of progress (URP);
(2) 40 CFR 51.308(f)(2): long-term strategy;
(3) 40 CFR 51.308(f)(3): reasonable progress goals (RPGs);
(4) 40 CFR 51.308(f)(4): reasonably attributable visibility
impairment (RAVI);
(5) 40 CFR 51.308(f)(5) and 40 CFR 51.308(g): progress report
requirements;
(6) 40 CFR 51.308(f)(6): monitoring strategy and other
implementation plan requirements; and
(7) 40 CFR 51.308(i): Federal Land Manager (FLM) consultation.
II. Background and Requirements for Regional Haze Plans
A detailed history and background of the regional haze program is
provided in multiple prior EPA proposal actions.\1\ For additional
background on the 2017 RHR revisions, please refer to section III of
this document. Overview of Visibility Protection Statutory Authority,
Regulation, and Implementation of ``Protection of Visibility:
Amendments
[[Page 6582]]
to Requirements for State Plans'' of the 2017 RHR.\2\ The following is
an abbreviated history and background of the regional haze program and
2017 Regional Haze Rule as it applies to the current action.
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\1\ See 90 FR 13516 (March 24, 2025).
\2\ See 82 FR 3078 (January 10, 2017, located at <a href="https://www.federalregister.gov/documents/2017/01/10/2017-00268/protection-of-visibility-amendments-to-requirements-for-State-plans#h-16">https://www.federalregister.gov/documents/2017/01/10/2017-00268/protection-of-visibility-amendments-to-requirements-for-State-plans#h-16</a>).
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A. Regional Haze
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. CAA section
169A. The CAA 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 section 169A(a)(1).
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 (SO<INF>2</INF>), nitrogen oxides (NO<INF>X</INF>), and, in
some cases, volatile organic compounds (VOC) and ammonia
(NH<INF>3</INF>)). Fine particle precursors react in the atmosphere to
form fine particulate matter (PM<INF>2.5</INF>), which impairs
visibility by scattering and absorbing light. Visibility impairment
reduces the perception of clarity and color, as well as visible
distance.\3\
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\3\ 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<SUP>-</SUP>\1\). The formula for the deciview is 10 ln (b\ext\)/
10 Mm<SUP>-1</SUP>). 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 section 169A(b)(2); see also 40 CFR
51.308(b), (f) (establishing submission dates for iterative regional
haze SIP revisions); (64 FR at 35768, July 1, 1999).
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 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).
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), 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.
The Central Regional Air Planning Association (CenRAP), one of the
five RPOs described above, that Oklahoma was a member of during the
first planning period, was a collaborative effort of state governments,
Tribal governments, and Federal agencies established to initiate and
coordinate activities associated with the management of regional haze,
visibility, and other air quality issues in parts of the Great Plains,
Midwest, Southwest, and South Regions of the United States.
After the first planning period SIPs were submitted, the planning
was shifted to the Central State Air Resources Agencies (CenSARA).
CenSARA is a collaborative effort of state governments established to
initiate and coordinate activities associated with the management of
Regional Haze and other air quality issues in parts of the Great
Plains, Midwest, Southwest, and South Regions of the United States.
Member states include: Arkansas, Iowa, Kansas, Louisiana, Missouri,
Nebraska, Oklahoma, and Texas. Unlike CenRAP, CenSARA has solely state
members. However, CenSARA does reach out to Tribal and Federal
partners. The Federal partners of CenSARA are the EPA, the U.S.
National Parks Service (NPS), the U.S. Fish and Wildlife Service (FWS),
and the U.S. Forest Service (USFS).
C. Status of Oklahoma's Regional Haze Plan for the First Implementation
Period
Oklahoma submitted its regional haze SIP for the first
implementation period to the EPA on February 19, 2010. The EPA
partially approved and partially disapproved Oklahoma's first
implementation period regional haze SIP submission on December 28, 2011
(76 FR 81728, December 28, 2011). In that final rule, we disapproved
Oklahoma's SO<INF>2</INF> best available retrofit technology (BART)
determinations for the Oklahoma Gas and Electric (OG&E) Sooner Units 1
and 2, the OG&E Muskogee Units 4 and 5, and the American Electric
Power/Public Service Company of Oklahoma (AEP/PSO) Northeastern Units 3
and 4 and we disapproved the state's long-term strategy. To address
these deficiencies, the EPA promulgated a Federal Implementation Plan
(FIP) that imposed SO<INF>2</INF> BART emission limits for these six
units in the same final action. The EPA approved the remaining portions
of the 2010 Oklahoma regional haze SIP submission with the exception of
the reasonable progress requirements found at 40 CFR 51.308(d)(1), on
which we took no action in that final rule. We deferred consideration
of the reasonable progress requirements at the time, because in order
to properly assess whether Oklahoma had satisfied these requirements,
we first needed to evaluate and act upon the first planning period
regional haze SIP revision submitted by the State of Texas.
On June 20, 2013, Oklahoma submitted a regional haze SIP revision
to replace the FIP's SO<INF>2</INF> BART requirements for the AEP/PSO
Northeastern Units 3 and 4 and to make revisions to the NO<INF>X</INF>
BART compliance dates for the two units. On March 7, 2014 (79 FR 12944,
12954, March 7, 2014), we approved this SIP revision and concurrently
withdrew the FIP's applicability to these two units. The FIP provisions
applicable to the OG&E Muskogee and Sooner plants remain in place.
On January 5, 2016 (81 FR 296, January 5, 2016), we addressed the
outstanding portion of Oklahoma's first
[[Page 6583]]
planning period SIP related to the reasonable progress requirements
under 40 CFR 51.308(d)(1).\4\ Specifically, we disapproved the portion
of Oklahoma's 2010 Oklahoma regional haze SIP submission that addressed
40 CFR 51.308(d)(1), with the exception of the minimum progress
requirement under 40 CFR 51.308(d)(1)(vi), which we approved.\5\ The
disapproval stemmed from consideration of impacts from Texas sources in
establishing the reasonable progress goals for Oklahoma's Class I area,
Wichita Mountains Wilderness Area (Wichita Mountains). In that same
action, we promulgated a FIP for both Texas and Oklahoma to address the
identified deficiencies in the Texas and Oklahoma regional haze SIP for
the first planning period.\6\
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\4\ The January 5, 2016 (81 FR 296), final rule also addressed
the first planning period regional haze requirements in Texas except
for BART requirements for electric generating units (EGUs) and
partially approved and partially disapproved Texas's March 31, 2009,
SIP.
\5\ The disapproved portions included disapproving Oklahoma's
2018 RPGs for Wichita Mountains and other elements related to
reasonable progress, including the requirement to adequately consult
with other states that may reasonably be anticipated to cause or
contribute to visibility impairment at the Wichita Mountains and the
requirement to adequately justify RPGs that are less stringent than
the URP.
\6\ Specific to Oklahoma, the FIP reset Oklahoma's RPGs based on
our finding that the controls we finalized for the Texas FIP also
served to cure the defects in these sections of Oklahoma's regional
haze SIP as well, thus satisfying the FIP obligation stemming from
our disapproval of portions of the Oklahoma SIP.
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The January 5, 2016, final rule was challenged in the U.S. Court of
Appeals for the Fifth Circuit (Fifth Circuit) and was stayed by the
court on July 15, 2016.\7\ Considering the stay, the EPA requested a
partial voluntary remand of the January 5, 2016, final rule, which was
granted by the Fifth Circuit on March 22, 2017.\8\ On July 26, 2023 (88
FR 48152, July 26, 2023), the EPA proposed a rule to address the
remanded January 5, 2016, final rule, and proposed to disapprove the
same portions of the Texas and Oklahoma SIPs which had been previously
disapproved in the January 5, 2016, final rule and amend the FIP
portion of the rule.\9\
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\7\ Texas v. EPA, 829 F.3d 405, 411 (5th Cir. 2016).
\8\ Texas v. EPA, Case No. 16-60118, Order (March 22, 2017).
\9\ In certain instances, supplementing and clarifying our
rationale for disapproval and, in others, incorporating our original
bases for disapproval. The proposed amendments to the FIP portions
of the final rule included rescinding the control measures
previously promulgated for 15 EGUs in Texas. EPA also proposed to
find that no further federal action was needed to remedy those
deficiencies.
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On September 3, 2024, the EPA filed a motion for voluntary
vacatur,\10\ and the Fifth Circuit granted the EPA's motion on December
17, 2024, vacating the SIP disapproval and FIP portions of the January
5, 2016, final rule.\11\
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\10\ During remand proceedings, notably while working to respond
to the public comments received on the July 26, 2023, proposed rule,
the EPA became aware that key documents in the administrative record
of the January 5, 2016, final rule were no longer in the EPA's
possession. EPA filed motion for voluntary vacatur, acknowledging
that the administrative record no longer contained information
required by the Federal Rules of Appellate Procedure and the Clean
Air Act for judicial review of the EPA's partial SIP disapprovals
and FIPs. Respondents' Motion for Voluntary Vacatur, Texas v. EPA,
Case No. 16-60118 (September 3, 2024).
\11\ Texas v. EPA, Case No. 16-60118, Order (December 17, 2024).
Because the EPA's motion for vacatur was specific to the SIP
disapprovals and the FIPs and the Fifth Circuit granted this motion,
the court vacated the disapproval and FIP portions of the January 5,
2016, final rule, leaving the approvals intact.
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On December 12, 2025 (90 FR 56001), the EPA finalized approval of
portions of the Oklahoma regional haze SIP revision submitted on
February 19, 2010, that relate to reasonable progress requirements for
the first planning period from 2007 through 2018. Specifically, the EPA
approved the portion of the 2010 Oklahoma Regional Haze SIP that
addressed the requirements of 40 CFR 51.308(d)(1)(i) through (v).\12\
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\12\ In that same final rule (90 FR 56001, December 12, 2025),
EPA also approved SIP submittals from Texas dated March 20, 2014,
and July 20, 2021, as satisfying applicable requirements under the
CAA and RHR, as well as approved portions of the 2009 Texas Regional
Haze SIP that relate to reasonable progress requirements for the
first planning period. In the related May 23, 2025, proposal (90 FR
22166) for that final rule, EPA formally withdrew the proposed
disapprovals for portions of Texas and Oklahoma SIPs included as
part of the proposed rule published on July 26, 2023 (88 FR 48152).
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Pursuant to 40 CFR 51.308(g), Oklahoma was also responsible for
submitting a five-year progress report as a SIP revision for the first
implementation period, which it did on September 28, 2016. The EPA
approved the progress report into the Oklahoma SIP on June 28, 2019 (84
FR 30918, June 28, 2019).
D. Oklahoma's Regional Haze Plan for the Second Implementation Period
On August 9, 2022, the Oklahoma Department of Environmental Quality
(ODEQ) \13\ submitted a revision to the Oklahoma SIP to address
regional haze for the second planning period (2018-2028).\14\ Oklahoma
made this SIP submission to satisfy the requirements of the CAA's
regional haze program pursuant to CAA sections 169A and 169B and 40 CFR
51.308. Oklahoma's 2022 SIP submission contains the State's evaluation
of which measures to include in its long-term strategy to address
regional haze visibility impairment for each Class I area within the
State and each Class I area outside the State that may be affected by
emissions from the State. The State examined the need to implement
additional enforceable emission limitations, compliance schedules, and
other measures that may be necessary to make reasonable progress since
the first implementation period. Specifically, Oklahoma's 2022 SIP
submission contains an assessment of visibility progress made at Class
I areas since the first implementation period and the State's
determinations regarding a long-term strategy to address regional haze
visibility impairment at the Class I areas the State identified,
including: Oklahoma's selection of sources that may affect visibility
in impacted Class I areas; its evaluation of the selected sources to
determine what emission reduction measures may be necessary to achieve
reasonable progress for the long-term strategy, through consideration
of the four statutory factors; and ultimately, Oklahoma's
determinations on what measures are necessary for the long-term
strategy to address regional haze visibility impairment in Class I
areas.
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\13\ In this document, ODEQ and Oklahoma are used
interchangeably.
\14\ On January 20, 2026, Oklahoma provided a signed agreement
to EPA for one of the facilities as a clarification to the
requirements in the SIP.
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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 section 169A(b)(2)(B). To this end, 40 CFR
51.308(f) lays out the process by which states determine what
constitutes their long-term strategies, with the order of the
requirements in 40 CFR 51.308(f)(1) through (3) generally mirroring the
order of the steps in the reasonable progress analysis \15\ and (f)(4)
[[Page 6584]]
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 (five-year average period of
2000-2004), current, and natural visibility conditions (i.e.,
visibility conditions without anthropogenic visibility impairment) for
that area, as well as the visibility improvement made to date and the
URP. The URP is 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 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. 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'' \16\ 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) through (3). There are additional
requirements in the rule, including FLM consultation, that apply to all
visibility protection SIPs and SIP revisions. See e.g., 40 CFR
51.308(i).
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\15\ 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 51.308(d), ``tracked the actual planning
sequence.'' (82 FR 3078, at 3091, January 10, 2017).
\16\ The five ``additional factors'' for consideration in 40 CFR
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.
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While states have discretion to choose any source selection
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.\17\ This is accomplished by considering the four factors--``the
costs of compliance, the time necessary for compliance, and the energy
and non-air quality environmental impacts of compliance, and the
remaining useful life of any existing source subject to such
requirements.'' CAA section 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,\18\ a state must
consider a ``meaningful set'' of technically feasible control options
for reducing emissions of visibility impairing pollutants. Id. at 3088.
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\17\ The CAA provides that, ``[i]n determining reasonable
progress there shall be taken into consideration'' the four
statutory factors. CAA section 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.
\18\ ``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.
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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.\19\ Ultimately, while states have discretion to
reasonably weigh the factors and to determine what level of control is
needed, 40 CFR 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.''
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\19\ 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 No. EPA-HQ-OAR-2015-0531,
U.S. Environmental Protection Agency at 186.
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As explained above, 40 CFR 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 40 CFR 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. If the outcome
of a four-factor analysis is that an emissions reduction measure is
necessary to make reasonable progress towards remedying existing or
preventing future anthropogenic visibility impairment, that measure
must be included in the SIP.
The characterization of information on each of the factors is also
subject to the documentation requirement in section 51.308(f)(2)(iii).
The reasonable progress analysis is a technically complex exercise, and
also a flexible one that provides states with bounded discretion to
design and implement approaches appropriate to their circumstances.
Given this flexibility, 40 CFR 51.308(f)(2)(iii) plays an important
function in requiring a state to document the technical basis for its
[[Page 6585]]
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. Additionally, the RHR at 40 CFR 51.3108(f)(2)(iv)
separately provides five ``additional factors'' \20\ 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.
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\20\ The five ``additional factors'' for consideration in 40 CFR
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.
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Because the air pollution that causes regional haze crosses state
boundaries, 40 CFR 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. 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). Under all
circumstances, a state must document in its SIP submission all
substantive consultations with other contributing states. 40 CFR
51.308(f)(2)(ii)(C).
A. 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.
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).While states are not legally obligated to achieve the
visibility conditions described in their RPGs, 40 CFR 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.''
RPGs may also serve as a metric for assessing the amount of
progress a state is making towards the national visibility goal. To
support this approach, 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.''
B. 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. 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). 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, as well as a statewide inventory documenting
such emissions. 40 CFR 51.308(f)(6)(ii), (iii), and (v). 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).
C. 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 assess changes in
visibility conditions and 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).
D. Requirements for State and 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
[[Page 6586]]
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). 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 Oklahoma's Regional Haze Plan for the
Second Implementation Period
In section IV of this document, we describe Oklahoma's 2022 SIP
submission and evaluate it against the requirements of the CAA and RHR
for the second implementation period of the regional haze program.
A. Identification of Class I Areas
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 long-term strategy for making reasonable
progress toward the national visibility goal. The RHR implements this
statutory requirement in 40 CFR 51.308(f) for the second and subsequent
planning periods for regional haze. Section 51.308(f)(2) 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.
To address 40 CFR 51.308(f), Oklahoma identified the one mandatory
Class I Federal area within its borders, the Wichita Mountains
Wilderness, located in the Wichita Mountains National Wildlife Refuge
in Comanche County, in the southeast part of Oklahoma. Wichita
Mountains Wilderness is managed by the US Fish and Wildlife Service
(FWS).
To work collectively on regional haze SIP development for the
second planning period, CenSARA contracted Ramboll-Environ to produce
an area of influence (AOI) study for the region (CenSARA 2018 AOI
analysis).\21\ The CenSARA 2018 AOI analysis was developed to estimate
impacts from individual stationary sources on visibility conditions at
Class I areas of interest. Oklahoma relied on this AOI analysis to
identify sources within Oklahoma with the potential for impairing
visibility at the Wichita Mountains and Class I areas in neighboring
states. Oklahoma initially assessed five Class I areas outside the
state for potential visibility impacts by Oklahoma sources. Through
consultation with neighboring states and Oklahoma's own analysis using
the results of the CenSARA 2018 AOI analysis, Oklahoma identified three
of those Class I areas outside the state as having potential visibility
impacts from Oklahoma emission sources: Caney Creek Wilderness Area and
Upper Buffalo Wilderness Area in Arkansas and Hercules-Glades
Wilderness Area in Missouri.\22\
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\21\ See Oklahoma's 2022 SIP submission, appendices B and C, for
the complete AOI outputs and the corresponding report on the CenSARA
2018 AOI analysis.
\22\ See Oklahoma's 2022 SIP submission, p. 46-47. Although
table 2-1 of Oklahoma's 2022 SIP submission also initially
identified Guadalupe Mountains National Park and Big Bend National
Park in Texas ``for potential visibility impacts from the transport
of pollutants from Oklahoma emission sources,'' Oklahoma did not
identify any sources in Oklahoma as potentially impacting the Texas
Class I areas based on Oklahoma's source selection methodology as
described in this subsection nor did the Texas Commission on
Environmental Quality (TCEQ) communicate to ODEQ that any sources in
Oklahoma were reasonably anticipated to impair visibility at Texas
Class I areas.
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More information on how Oklahoma used the CenSARA 2018 AOI analysis
to identify sources that could potentially impact visibility in Class I
areas within and outside Oklahoma and to conduct its four-factor
analysis is discussed in section IV.C.1 of this document.
EPA agrees with Oklahoma's conclusions that they properly
identified Class I areas within and outside of Oklahoma that may be
affected by emissions from within the State due to the following: (1)
the State analyzed its statewide sulfate and nitrate contributions to
total visibility impairment at out-of-state Class I areas; (2) none of
the Class I areas that Oklahoma sources contribute to have 2028 RPGs on
the 20 percent most impaired days above the URP; \23\ (3) Oklahoma
analyzed its in-state and out-of-state impacts through the AOI
analysis; and (4) the State completed consultation with CenSARA States
via the RPO processes.
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\23\ For more information on the RPGs of these three Class I
areas outside of Oklahoma, see section IV.D of this document.
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B. Calculations of Baseline, Current, and Natural Visibility
Conditions; Progress to Date; and Uniform Rate of Progress for Class I
Areas Within the State
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).
In sections 3, 6.1, and 7 of Oklahoma's 2022 SIP submission,
Oklahoma determines and presents the baseline, natural, and current
visibility conditions for both the 20 percent most anthropogenically
impaired days and the 20 percent clearest days for the State's Class I
area, Wichita Mountains Wilderness, consistent with the EPA's RHR and
guidance, and through the use of IMPROVE monitoring data. Oklahoma
calculated baseline visibility based on data from 2002-2004, as the
IMPROVE monitoring site at Wichita Mountains Wilderness was not
established until 2001. Oklahoma determined that Wichita Mountains
Wilderness has, respectively, on the 20 percent clearest days and 20
percent most impaired days: (1) 2000-2004 baseline visibility
conditions of 9.92 deciviews and 22.18 deciviews; (2) 2015-2019 current
visibility conditions of 8.33 deciviews and 17.56 deciviews; and (3)
natural visibility conditions of 4.20 deciviews and 10.19 deciviews.
[[Page 6587]]
This information is also provided in table 1 of this document.
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\24\ EPA notes that table 6-1 of Oklahoma's 2022 SIP submission
provides 2015-2019 current visibility values that are inconsistent
with other parts of the SIP. The most representative 2015-2019
visibility value from the SIP is used in this document.
Table 1--Baseline, Current, and Natural Visibility Index at Wichita Mountains \24\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Average deciview index for Average deciview index for Deciview index for natural
2000-2004 (baseline) 2015-2019 (current) conditions (2064)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Clearest Days............................................... 9.92 8.65 4.20
Most Impaired Days.......................................... 22.18 17.58 10.19
--------------------------------------------------------------------------------------------------------------------------------------------------------
In sections 3 and 5.4 of Oklahoma's 2022 SIP submission, Oklahoma
discusses the visibility progress in Wichita Mountains Wilderness. The
2015-2019 current visibility conditions for the most impaired days show
a 21 percent improvement over the 2000-2004 baseline visibility
conditions, with a 1.27 and 4.6 deciviews improvement from 2000-2004
baseline to 2015-2019 current visibility conditions for the 20 percent
clearest and most impaired days respectively. From information provided
in Oklahoma's 2022 SIP submission, EPA calculated the difference
between 2015-2019 current visibility and natural conditions, which show
a 4.13 and 7.37 deciviews difference for the 20 percent clearest and
most impaired days respectively. This information is provided in table
2 of this document.
Table 2--Visibility Progress to Date and Future Progress for Wichita Mountains
--------------------------------------------------------------------------------------------------------------------------------------------------------
Progress during last
Progress since baseline implementation period (2008- Difference between current (2014-
(2000-2004)-(2014-2018), in 2012)-(2014-2018), in 2018) and natural (2064), in
deciviews deciviews deciviews
--------------------------------------------------------------------------------------------------------------------------------------------------------
Clearest Days............................................... 1.27 1.02 4.13
Most Impaired Days.......................................... 4.6 3.11 7.37
--------------------------------------------------------------------------------------------------------------------------------------------------------
The RHR allows states the option to adjust the 2064 glidepath
endpoint to account for both international anthropogenic and certain
prescribed fire impacts at Class I areas. EPA's 2018 Visibility
Tracking Guidance \25\ provides recommendations to assist states in
satisfying their obligations under 40 CFR 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.\26\
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\25\ 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
<a href="https://www.epa.gov/visibility/guidance-tracking-progress-under-regional-haze-rule">https://www.epa.gov/visibility/guidance-tracking-progress-under-regional-haze-rule</a>.
\26\ See 82 FR 3078, p. 3103-3105 (January 10, 2017).
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Under 40 CFR 51.308(f)(1)(vi)(B), Oklahoma chose to adjust the URP
glidepath for the State's Class I area, Wichita Mountains Wilderness,
to account for impacts from anthropogenic sources outside the United
States and impacts from wildland prescribed fires.<SUP>27 28</SUP>
Oklahoma used photochemical modeling conducted by EPA used to project
visibility impairment at Class I areas in 2028 as part of its URP
determination.\29\ At Wichita Mountains, the unadjusted URP for 2028 is
16.06 deciviews. EPA's 2028 modeling provided for adjusted URP values
that accounts for contributions of international emissions. Based on
baseline, 2064 natural conditions, and EPA's default adjustment,
Oklahoma determined the 2028 URP for Wichita Mountains to be 17.36
deciviews for the 20 percent most impaired days.\30\
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\27\ Wildland prescribed fires are those conducted with the
objective to establish, restore, and/or maintain sustainable and
resilient wildland ecosystems, to reduce the risk of catastrophic
wildfires, and/or to preserve endangered or threatened species
during which appropriate basic smoke management practices were
applied. 40 CFR 51.308(f)(1)(vi)(B).
\28\ See Oklahoma's 2022 SIP submission, p. 50-51.
\29\ See EPA memorandum, ``Availability of Modeling Data and
Associated Technical Support Document for the EPA's Updated 2028
Visibility Air Quality Modeling'' (``EPA's 2028 modeling'' in this
document), dated September 19, 2019, available at <a href="https://www.epa.gov/visibility/technical-support-document-epas-updated-2028-regional-haze-modeling">https://www.epa.gov/visibility/technical-support-document-epas-updated-2028-regional-haze-modeling</a> and the docket for this document.
\30\ In EPA's 2028 modeling, at Wichita Mountains, 17.36
deciviews is provided as the default adjusted 2028 URP/glidepath,
with the minimum and maximum alternate glidepath values being 16.62
and 17.79 deciviews, respectively.
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The EPA is proposing to find that Oklahoma's regional haze plan
meets the requirements of 40 CFR 51.308(f)(1) related to the
calculations of baseline, current, and natural visibility conditions;
progress to date; and the uniform rate of progress for the second
implementation period.
C. Long-Term Strategy
Each state having a Class I area within its borders or emissions
that may affect visibility in any Class I area must develop a long-term
strategy for making reasonable progress towards the national visibility
goal for each impacted Class I area. CAA section 169A(b)(2)(B). After
considering the four statutory factors, all measures that are
determined to be necessary to make reasonable progress must be in the
long-term strategy. In developing its long-term strategy, a state must
also consider the five additional factors in 40 CFR 51.308(f)(2)(iv).
As part of its reasonable progress determinations, the state must
describe the criteria used to 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).
[[Page 6588]]
1. Summary of Oklahoma's Long-Term Strategy
a. Source Selection Methodology
Sections 6.2 and 6.3 in Oklahoma's 2022 SIP submission discuss
Oklahoma's long-term strategy development as well as source selection
methodology. As mentioned in section IV.A of this document, Oklahoma
relied on the CenSARA 2018 AOI analysis to identify sources within
Oklahoma with the potential for impairing visibility at the Wichita
Mountains and Class I areas in neighboring states. This section of this
document further discusses Oklahoma's source selection methodology,
including how Oklahoma used the CenSARA 2018 AOI analysis in developing
its long-term strategy.
In the report documenting the CenSARA 2018 AOI analysis (CenSARA
AOI report), it states that ``EPA's previous analysis of contributions
of individual PM components to total extinction on the 20 percent most
anthropogenically impaired days during 2010-2014 showed that sulfate
and nitrate are two major PM components that account for a large
fraction of the anthropogenic visibility impairment at these Class I
areas.'' \31\ The CenSARA AOI report also states that industrial
sources, including electric generating unit (EGU) and other industrial
point (non-EGU) sources, are major contributors to both SO<INF>2</INF>
and NO<INF>X</INF> emissions (precursors of sulfate and nitrate,
respectively).\32\ CenSARA chose to focus the AOI analysis on EGU and
non-EGU point sources since these sources comprise major fractions of
the SO<INF>2</INF> and NO<INF>X</INF> emissions inventory.\33\
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\31\ See Oklahoma's 2022 SIP submission, appendix B: Ramboll-
Environ Area-of-Influence Report, p. 5. In this proposal, we refer
to this document as the CenSARA AOI report.
\32\ See CenSARA AOI report, p. 3, in Oklahoma's 2022 SIP
submission, appendix B.
\33\ Id at 5.
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The Hybrid-Single Particle Lagrangian Integrated Trajectory
(HYSPLIT) back-trajectory model was used to generate 72-hour back
trajectories for each IMPROVE site (i.e., Class I area) of interest on
the 20 percent most impaired days for the five-year period from 2012 to
2016. Based on the five years of individual back trajectories on the
most 20 percent most impaired days, trajectory paths were mapped into
36-kilometer (km) by 36-km horizontal grid cells and residence time
data were generated for each IMPROVE site. The residence time is the
cumulative time that trajectories reside in a specific geographical
area (e.g., a grid cell of a modeling domain) and are usually
normalized to display percentage of total trajectory time. To define
geographical areas with a high probability of influencing visibility
(i.e., the area of influence) at each IMPROVE site that has impairment
due to sulfate and nitrate, extinction weighted residence time (EWRT)
plots were generated separately for sulfate and nitrate. To determine
the potential impact from individual point sources, the EWRT values for
sulfate and nitrate were combined with facility-level emissions (Q) of
SO<INF>2</INF> and NO<INF>X</INF> (respectively) using emissions data
from the 2016 EPA modeling platform and 2028 emissions projections.\34\
To incorporate the effects of dispersion, deposition and chemical
transformation along the path of the trajectories, emissions were
inversely weighted by the distance (d) between the centers of the grid
cell emitting the emissions and the grid cell containing the IMPROVE
site. This resulted in EWRT*Q/d values for SO<INF>2</INF> and
NO<INF>X</INF> (separately) for each stationary source for each IMPROVE
site. Oklahoma's methodology for identifying Oklahoma sources that may
impact visibility at Wichita Mountains and Class I areas in other
states using the results of the CenSARA 2018 AOI analysis is discussed
in the paragraphs that follow.
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\34\ For more information, see the EPA memorandum,
``Availability of Modeling Data and Associated Technical Support
Document for the EPA's Updated 2028 Visibility Air Quality
Modeling'' (``EPA's 2028 modeling'' in this document), dated
September 19, 2019, available at <a href="https://www.epa.gov/visibility/technical-support-document-epas-updated-2028-regional-haze-modeling">https://www.epa.gov/visibility/technical-support-document-epas-updated-2028-regional-haze-modeling</a>
and the docket for this document.
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Oklahoma's 2022 SIP submission noted that implementation of BART
determinations for the first planning period continued beyond 2016,
which was used as the baseline emissions year for conducting the AOI
study. This means that some BART emission reductions that took place
after 2016 are not reflected in the emissions inventory used in the AOI
study. In identifying sources for analysis, Oklahoma chose to use
emissions from the same year for every source to avoid potential
misrepresentation of effects of emission controls. Oklahoma also noted
that due to the substantial variation in weather conditions among
years, the use of an inventory for a different, more recent year than
the year of the meteorological analysis in the CenSARA 2018 AOI
analysis would introduce uncertainty and indefensible inconsistencies.
However, based on suggestions from EPA during early SIP development,
Oklahoma decided to remove some sources and their corresponding
emissions from the source selection calculations. These eliminations
were done in an effort to not skew the source selection criteria
towards sources that had already achieved significant, known reductions
that were not reflected in the 2016 emissions data.\35\
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\35\ The sources whose emissions contributions were removed are
documented in appendix D of Oklahoma's 2022 SIP submission. The
sources include Big Brown Steam Electric Station, Sandow Steam
Electric Station and the Monticello Steam Electric Station located
in Texas; and OG&E Muskogee Generating Station and OG&E Sooner
Generating Station in Oklahoma.
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In evaluating individual source contribution to visibility
impairment, Oklahoma considered NO<INF>X</INF> and SO<INF>2</INF>
emissions separately instead of aggregating contributions from each
pollutant for a total source contribution. Visibility impairment at the
Wichita Mountains is dominated by NO<INF>X</INF> in winter conditions
and SO<INF>2</INF> in the majority of the remainder of the year. To
justify considering source contribution to visibility impairment due to
NO<INF>X</INF> and SO<INF>2</INF> emissions separately, the SIP
submittal stated that there is the possibility that controlling one,
but not both pollutants, is cost effective and also noted that
conducting four-factor analyses is resource intensive.
[[Page 6589]]
After analyzing the results of the CenSARA 2018 AOI analysis and
removing emissions from sources with known large reductions from its
source selection calculations, Oklahoma applied a ``Q/d'' threshold of
5.0 tons per km (tons/km) or greater (for SO<INF>2</INF> and
NO<INF>X</INF> separately) to screen out small sources in Oklahoma from
further analysis.\36\ Oklahoma's 2022 SIP submission stated that while
using EWRT's is useful for identifying large geographic areas likely to
contain sources of visibility impairing emissions, photochemical
modeling has suggested that EWRT tends to over-emphasize small sources
of emissions located close to Class I areas. Because the AOI analysis
goes back only 72 hours, it does not analyze long-range transport or
emissions in more distant areas. Visibility-degrading fine particulate
matter commonly travels in the atmosphere for two weeks or longer after
emission. The SIP submittal stated that in order to help alleviate this
over-emphasis on small sources, Oklahoma opted to consider a ``Q/d,''
or emissions mass divided by distance, threshold of 5.0 tons/km for
eliminating small sources from further analysis. Oklahoma then applied
an individual source contribution threshold (i.e., percent EWRT*Q/d) of
0.5 percent or greater for sulfate and nitrate separately. Oklahoma
stated in its SIP submittal that given the successful reduction in
visibility impairment over the last decade, 0.5 percent is an
appropriate threshold for identifying sources of the greatest
importance for further analysis.
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\36\ Oklahoma selected and applied a ``Q/d'' threshold of 5.0
tons per km (tons/km) to its dataset to screen out small sources in
Oklahoma from consideration in a four-factor analysis, where ``Q''
is the facility-level 2016 annual tons of emissions of
NO<INF>X</INF> or SO<INF>2</INF> and ``d'' is the distance of the
facility from the Class I area of interest in km.
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Additionally, some point sources identified as having the potential
to impact a Class I area based on Oklahoma's source selection
methodology described in the preceding paragraphs were eliminated from
further consideration if their emissions are impacted by participation
in the Cross State Air Pollution Rule (CSAPR) or upon consideration of
the impact of emission reductions due to BART requirements not fully
implemented during the first planning period. Oklahoma chose to defer
focus on those sources until a later regional haze planning period to
allow the full benefits and implementation of BART and CSAPR to mature.
Using the methodology described in the previous paragraphs,
Oklahoma identified twelve sources for further analysis.\37\ Tables 6-2
and 6-3 of Oklahoma's 2022 SIP submission contain the sources that
Oklahoma evaluated for possible four-factor analysis, and the final
sources selected for evaluation are listed in sections 6.4.1 and 6.4.2
of its SIP. These twelve sources are also listed in table 3.
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\37\ See Oklahoma's 2022 SIP submission, p. 37-44.
Table 3--Oklahoma Sources Subject to Four-Factor Analysis in Oklahoma's 2022 SIP Submission
----------------------------------------------------------------------------------------------------------------
Oklahoma source subject to four-
factor analysis Location Type of source
----------------------------------------------------------------------------------------------------------------
1. Oxbow Calcining LLC--Kremlin Garfield County......................... SO2
Calcined Coke Plant.
2. Western Farmers Electric Choctaw County.......................... SO2
Cooperative (Western Farmers)--
Hugo Electric Generating Plant.
3. Grand River Dam Authority Mayes County............................ SO2
(GRDA)--Grand River Energy Center
(GREC).
4. Holcim US Inc.--Ada Portland Pontotoc County......................... SO2
Cement Production Plant.
5. Continental Carbon Co.--Carbon Kay County.............................. SO2
Black Production Facility.
6. Oklahoma Gas and Electric Oklahoma County......................... NOX
Company (OG&E)--Horseshoe Lake
Generating Station.
7. OG&E--Mustang Generating Station Canadian County......................... NOX
8. Mustang Gas Products--Binger Gas Caddo County............................ NOX
Plant.
9. ONEOK Field Services--Lindsay Garvin County........................... NOX
Booster Station.
10. ONEOK Field Services--Maysville Garvin County........................... NOX
Gas Plant.
11. Panhandle Eastern Pipeline Co.-- Kingfisher County....................... NOX
Cashion Compressor Station.
12. DCP Operating Co.--Chitwood Gas Grady County............................ NOX
Plant.
----------------------------------------------------------------------------------------------------------------
b. Four-Factor Analysis
Sections 6.4.1 and 6.4.2. of Oklahoma's 2022 SIP submission discuss
the State's four-factor analysis of the selected Oklahoma sources in
more detail. Oklahoma requested and received information from the
owners or operators of the twelve sources (seven sources of
NO<INF>X</INF> emissions and five sources of SO<INF>2</INF> emissions)
listed in table 3. Sources were instructed by Oklahoma to provide
additional information regarding the status of their units and to
perform a four-factor analysis for their selected pollutant.
Information and four-factor analyses submitted by the Oklahoma sources
are found in appendix E of Oklahoma's 2022 SIP submission. To address
comments received on Oklahoma's draft 2022 SIP revision, Oklahoma
requested and received additional information from sources prior to
submission of the final package to EPA. When developing its long-term
strategy, Oklahoma considered the four factors (i.e., 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 the source), taking into account the information and analyses
received from the sources. A summary of Oklahoma's four-factor analysis
results is provided in table 6-4 of Oklahoma's 2022 SIP submission. EPA
further discusses and evaluates Oklahoma's four-factor analysis results
and determination of controls of its selected sources in sections
IV.C.2.b.i through xii of this document.
More discussion on Oklahoma's cost threshold selections as part of
the control scenarios in its four-factor analyses are found in section
6.8 of Oklahoma's 2022 SIP. Oklahoma determined the cost-of-control
thresholds in dollars per ton of emissions saved to be $1,400 to $2,000
per ton and $5,000 per ton for NO<INF>X</INF> and SO<INF>2</INF>
respectively. Oklahoma looked to the Cross-State Air Pollution Rule
(CSAPR) to inform the selection of an appropriate cost threshold for
NO<INF>X</INF> controls. For SO<INF>2</INF> controls, Oklahoma also
notes that during discussions with CenSARA, other RPOs, and states,
$5,000 per ton has been widely used as a reasonable cost threshold.
Control options were determined by Oklahoma to be cost prohibitive in
most instances.
For NO<INF>X</INF>, Oklahoma found that only the Mustang Gas Binger
Gas Plant's two units were within Oklahoma's NO<INF>X</INF> cost
threshold. Mustang Gas Binger Gas Plant has already installed
appropriate
[[Page 6590]]
controls on one of its units, and Mustang Gas committed to installing
and operating additional controls at the remaining unit to meet updated
NO<INF>X</INF> emission limits (9.00 grams NO<INF>X</INF> per
horsepower-hour and 104.29 tons NO<INF>X</INF> per year). Mustang Gas
agreed to a Regional Haze Agreement with Oklahoma as the enforceable
mechanism for installing and operating controls at the remaining unit
upon EPA's approval of Oklahoma's 2022 SIP submission.\38\ Oklahoma
also discusses the already completed removal and replacement of eight
engines at the ONEOK Lindsay Booster Station and removal of seven
engines at the ONEOK Maysville Gas Plant, with a commitment from ONEOK
to remove the remaining six Maysville Gas Plant engines. ONEOK agreed
to a Regional Haze Agreement with Oklahoma as the enforceable mechanism
for removing the remaining natural gas-fueled engines by December 31,
2028.\39\ These measures at the ONEOK facilities precluded the need for
further analysis or selection of further controls at these sites.\40\
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\38\ See Oklahoma's 2022 SIP submission, section 6.4.2.3,
section 6.9, and the Mustang Gas Regional Haze Agreement, Case No.
26-008, effective 1/15/2026.
\39\ See Oklahoma's 2022 SIP submission, appendix F: ONEOK
Regional Haze Agreement, Case No. 22-085, effective 5/6/2022.
\40\ See Oklahoma's 2022 SIP submission, sections 6.4.2.4 and
6.4.2.5.
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For SO<INF>2</INF>, Oklahoma found that estimated SO<INF>2</INF>
control costs calculated varied greatly but were all found to be in
excess of Oklahoma's SO<INF>2</INF> cost threshold. Oklahoma provides
in its 2022 SIP submission that, given technical and cost
considerations, the analyses conducted were reasonable, and its plan
does not impose a requirement to install further SO<INF>2</INF>
controls on its selected sources or on any other sources during this
planning period. Oklahoma also concluded that even without additional
control measures, EPA's 2028 modeling projects further visibility
improvement at Wichita Mountains.
Additional discussion and summary of Oklahoma's long-term strategy
is provided in section 6.9 of Oklahoma's 2022 SIP submission. Oklahoma
states that due to the exceptional visibility progress from the first
planning period, and the cost prohibitive control options in the
current, second planning period, Oklahoma's 2022 SIP submission only
relies on existing air program rules and regulations in addition to
controls as part of its long-term strategy for the second planning
period. As provided in section IV.C.3 of this document and sections
6.9.1, 6.9.2, and 6.9.3 of Oklahoma's 2022 SIP submission, Oklahoma
also relies on other factors as part of its long-term strategy,
including ongoing air pollution control programs, measures for smoke
management and reducing impacts from construction activities. Ongoing
air pollution control programs include Oklahoma's major source and
minor facility permitting program and enforcement program, Federal new
source performance standards (NSPS), programs approved in Oklahoma's
SIP designed to address National Ambient Air Quality Standards (NAAQS)
requirements, and other Federal rules.
2. The EPA's Rationale and Evaluation of Oklahoma's Long-Term Strategy
In this section of this document, we evaluate Oklahoma's
determinations of the measures necessary to make reasonable progress
(i.e., its long-term strategy) against the requirements of the CAA and
RHR for the second implementation period of the regional haze program
and describe our rationale for proposing approval. Considering the four
statutory factors and the projected 2028 visibility conditions for
Class I areas in Oklahoma and those influenced by emissions from
Oklahoma sources, which are below the URP, the EPA finds that Oklahoma
reasonably determined the emission reduction measures that are
necessary to make reasonable progress for the second planning period.
As detailed further in this section, the EPA proposes to approve
Oklahoma's long-term strategy under 40 CFR 51.308(f)(2).
a. The EPA's Rationale for Proposing Approval
In this proposed action, we note that it is the Agency's policy, as
announced in our recent approval of the West Virginia Regional Haze
SIP,\41\ that where visibility conditions for a Class I area impacted
by a State are below the 2028 URP and the State has also evaluated
potential control measures by considering the four statutory factors,
the State will have presumptively demonstrated reasonable progress for
the second planning period for that area. We acknowledge that this
reflects a change in policy as to how the URP should be used in the
evaluation of regional haze second planning period SIPs. However, we
find that this policy better aligns with the purpose of the statute and
RHR, which is achieving ``reasonable'' progress, not maximal progress,
toward Congress's natural visibility goal. We explain the background
and our rationale on this change in policy further in this section.
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\41\ See EPA's final action for West Virginia's regional haze
SIP at 90 FR 29737 (July 7, 2025), and our notice of proposed
rulemaking at 90 FR 16478, 16483 (April 18, 2025) which describes
the policy. See also EPA's notice of proposed rulemaking for South
Dakota at 90 FR 20425 (May 14, 2025).
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In developing the regulations required by CAA section 169A(b), the
EPA established the concept of the uniform rate of progress (URP) for
each Class I area. The URP is determined by drawing a straight line
from the measured 2000-2004 baseline conditions (in deciviews) for the
20% most impaired days at each Class I area to the estimated natural
conditions (in deciviews) for the 20% most impaired days in 2064. From
this calculation, a URP value can be calculated for each year between
2004 and 2064. The EPA developed the URP to address the diverse
concerns of Eastern and Western states and account for the varying
levels of visibility impairment in Class I areas around the country
while ensuring an equitable approach nationwide. For each Class I area,
states must calculate the URP for the end of each planning period
(e.g., in 2028 for the second planning period).\42\ 40 CFR
51.308(f)(1)(vi)(A). States may also adjust the URP to account for
impacts from anthropogenic sources outside the United States and/or
impacts from certain wildland prescribed fires. 40 CFR
51.308(f)(1)(vi). Then, for each Class I area, states must compare the
reasonable progress goal (RPG) for the 20% most impaired days to the
URP for the end of the planning period. If the RPG is above the URP,
then an additional ``robust demonstration'' requirement is triggered
for each state that contributes to that Class I area. 40 CFR
51.308(f)(3)(ii).
---------------------------------------------------------------------------
\42\ We note that RPGs are a regulatory construct that we
developed to address the statutory mandate in CAA section
169B(e)(1), which required our regulations to include ``criteria for
measuring `reasonable progress' toward the national goal.'' Under 40
CFR 51.308(f)(3)(ii), RPGs measure the progress that is projected to
be achieved by the control measures a state has determined are
necessary to make reasonable progress. Consistent with the 1999 RHR,
the RPGs are unenforceable, though they create a benchmark that
allows for analytical comparisons to the URP and mid-implementation-
period course corrections if necessary. 82 FR 3091-3092 (January 10,
2017).
---------------------------------------------------------------------------
The EPA has the discretion and authority to change policy. In FCC
v. Fox Television Stations, Inc., the U.S. Supreme Court plainly stated
that an agency is free to change a prior policy and ``need not
demonstrate . . . that the reasons for the new policy are better than
the reasons for the old one; it suffices that the new policy is
permissible under the statute, that there are good reasons for it, and
that the agency believes it to be better.'' 566 U.S.
[[Page 6591]]
502, 515 (2009) (referencing Motor Vehicle Mfrs. Ass'n of United
States, Inc. v. State Farm Mut. Auto. Ins. Co., 463 U.S. 29 (1983)).
See also Perez v. Mortgage Bankers Assn., 135 S. Ct. 1199 (2015). The
EPA believes that its recently adopted policy aligns with the purpose
of the statute and RHR, which is achieving ``reasonable'' progress, not
maximal progress, toward Congress' natural visibility goal.
In the 2017 RHR Revisions, the EPA addressed the role of the URP as
it relates to a state's development of its second planning period SIP.
82 FR 3078 (January 10, 2017). Specifically, in response to comments
suggesting that the URP should be considered a ``safe harbor'' that
relieve states of any obligation to consider the four statutory
factors, the EPA explained that the URP was not intended to be such a
safe harbor. Id. at 3099. ``Some commenters stated a desire for
corresponding rule text dealing with situations where RPGs are equal to
(``on'') or better than (``below'') the URP or glidepath. Several
commenters stated that the URP or glidepath should be a `safe harbor,'
opining that states should be permitted to analyze whether projected
visibility conditions for the end of the implementation period will be
on or below the glidepath based on on-the-books or on-the-way control
measures, and that in such cases a four-factor analysis should not be
required.'' Id.
Other 2017 RHR comments indicated a similar approach, such as ``a
somewhat narrower entrance to a `safe harbor,''' by suggesting that if
current visibility conditions are already below the end-of-planning-
period point on the URP line, a four-factor analysis should not be
required.'' Id. The EPA stated in its response that we did not agree
with either of these recommendations. ``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 natural
visibility goal in every implementation period.'' Id.
However, so long as a state considers the four factors, the
presumption that a Class I area below the URP is achieving reasonable
progress is consistent with the CAA and RHR. Indeed, we believe this
policy also recognizes the considerable improvements in visibility
impairment that have been made by a wide variety of State and Federal
programs in recent decades. In sum, Oklahoma selected a number of
sources, evaluated emissions control measures, and considered the four
statutory factors. In addition, visibility conditions at all Class I
areas to which Oklahoma contributes are below the URP. In light of
these facts, the EPA agrees with Oklahoma's conclusion that no
additional measures are necessary to make reasonable progress during
the second planning period and is proposing to approve the state's SIP
submittal. The EPA's determinations are described in more detail in the
following section.
b. The EPA's Evaluation of Oklahoma's Long-Term Strategy
Applying the new policy as described in the previous section in our
evaluation of Oklahoma's SIP and as further detailed in the paragraphs
that follow, the EPA proposes to agree that the long-term strategy
outlined in Oklahoma's 2022 SIP submission is adequate to achieve
reasonable progress towards natural visibility at Class I areas
impacted by emissions from Oklahoma sources. The following paragraphs
contain a summary of the four factor analysis and EPA's evaluation of
each source evaluated by Oklahoma for further controls as part of
Oklahoma's long-term strategy.
i. Oxbow Calcining--Kremlin Calcined Coke Plant (SO<INF>2</INF>)
Oxbow Calcining's Kremlin Calcined Coke Plant, a petroleum coke
calcining plant located in Garfield County, was identified for further
analysis by Oklahoma for the evaluation of controls for SO<INF>2</INF>
emissions. The Oxbow Kremlin Plant utilizes three kilns in the
calcining process and reported emissions of 12,663 tons of
SO<INF>2</INF> in 2016. Oxbow considered three emissions reduction
options for each of the kilns at the plant: wet flue gas
desulfurization (WFGD), dry flue gas desulfurization (DFGD), and dry
sorbent injection (DSI). As provided in Oxbow's response to Oklahoma's
information collection request, WFGD, DFGD, and DSI would have a
potential control efficiency of 94%, 92%, and 40% SO<INF>2</INF>
removal, respectively. Oklahoma stated in its SIP that Oxbow was unable
to verify whether these particular control systems have been used
successfully on petroleum coke calcining kilns at other locations but
still evaluated each kiln for these controls. Oxbow also stated that
there was a high-level of uncertainty about the availability of water
that would be required to operate any of the controls, which added to
the potential technical infeasibility of the control options.\43\
---------------------------------------------------------------------------
\43\ See Oklahoma's 2022 SIP submission, section 6.4.1.1, p. 39-
40, and appendix E.
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In Oxbow's response to Oklahoma, Oxbow provided two different cost
calculations on potential controls depending on the two water supply
scenarios: the construction of a separate pipeline to the Kremlin Plant
from the City of Enid and obtaining water via trucks. For the time
necessary for compliance, Oxbow proposed a minimum of five years for
implementing either the WFGD option or the DFGD option and two years
for the DSI option and included an implementation schedule for
equipment design, procurement, fabrication, construction, and
commissioning. For the remaining useful life, Oxbow stated that, for
the purposes of the control cost assessment, an industry standard 20-
year remaining useful life is used, which is consistent with the EPA
Air Pollution Control Cost Manual (EPA Control Cost Manual).\44\ Oxbow
stated that it has no plans to shut down any of the kilns, and there
are no enforceable limitations on the remaining useful life of the
kilns. In consideration of the energy and non-air quality environmental
impacts of compliance, Oxbow also stated that all of the control
options provided would require additional energy for operation and
would result in various non-air quality environmental impacts primarily
related to additional water usage, wastewater management, and solid
waste management.\45\
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\44\ See <a href="https://www.epa.gov/economic-and-cost-analysis-air-pollution-regulations/cost-reports-and-guidance-air-pollution#cost%20manual">https://www.epa.gov/economic-and-cost-analysis-air-pollution-regulations/cost-reports-and-guidance-air-pollution#cost%20manual</a>.
\45\ See Oklahoma's 2022 SIP submission, section 6.4.1.1, p. 39-
40, and appendix E.
---------------------------------------------------------------------------
Oxbow used a 10% interest rate to calculate the annualized capital
costs of each control scenario for each kiln based on confidential
company-specific capital market information. Oxbow's calculated cost
effectiveness of controls, in dollars per ton of SO<INF>2</INF>
removed, ranged from $6,574 to $25,049 for the City of Enid water
supply scenario, and $12,707 to $42,258 for the trucked-in water supply
scenario. Oxbow's cost estimates of its trucked-in water supply
scenario were almost twice as much as the City of Enid water supply
scenario. All cost estimates at Oxbow's Kremlin Plant were higher than
Oklahoma's cost threshold of $5,000 per ton of SO<INF>2</INF> removed,
with the lowest cost control estimate at the Oxbow Kremlin Plant being
WFGD for Kiln 1, at $6,574, using the City of Enid water supply
scenario. Oxbow concluded and Oklahoma concurred that none of the
control options were economically viable due to
[[Page 6592]]
the cost and the technical uncertainty of the control technologies and
determined that no additional controls are reasonable during the second
planning period.\46\
---------------------------------------------------------------------------
\46\ Id.
---------------------------------------------------------------------------
EPA is proposing to find that the State's determination that no
measures for the Oxbow Kremlin Plant are necessary for reasonable
progress is reasonable and meets regional haze requirements for the
second planning period. In Oklahoma's 2022 SIP submission, Oklahoma
adequately considered the four statutory factors on the selected
control technologies for the three kilns at the Oxbow Kremlin Plant and
concluded that no measures are necessary to make reasonable progress
for the second planning period at the plant. In addition, the projected
2028 visibility conditions at Wichita Mountains to which the Oxbow
Kremlin Plant contributes is below its 2028 URP values. The EPA is
proposing to find that Oklahoma demonstrated that it is making
reasonable progress for the second planning period without requiring
any control measures for Oxbow Calcining's Kremlin Calcined Coke Plant.
ii. Western Farmers--Hugo Electric Generating Plant (SO<INF>2</INF>)
Western Farmers Electric Cooperative's Hugo Electric Generating
Plant is located in Choctaw County and was also identified for analysis
for potential SO<INF>2</INF> controls. The Western Farmers Hugo Plant
has one coal-fired boiler used to generate electricity and reported
7,275 tons of SO<INF>2</INF> emissions in 2016. As provided in Western
Farmer's response to Oklahoma's information collection request, Western
Farmers stated that 2018-2019 data for the facility was more
representative of future operations at the facility and provided
updated data with a baseline emission rate of 3,211 tons SO<INF>2</INF>
per year. Three emissions reduction options were considered for the
boiler at the plant: WFGD, DFGD, and DSI. Based on the data provided by
Western Farmers in its response to Oklahoma, WFGD, DFGD, and DSI would
have an estimated control efficiency of 91%, 87%, and 13%
SO<INF>2</INF> removal, respectively.\47\
---------------------------------------------------------------------------
\47\ See Oklahoma's 2022 SIP submission, section 6.4.1.2, p. 40-
41, and appendix E.
---------------------------------------------------------------------------
Western Farmers considered the four factors in its response to
Oklahoma. For time necessary for compliance, Western Farmers estimated
five years for implementing either WFGD or DFGD, citing consistency
with EPA's March 2011 Technical Support Document for the Oklahoma
Regional Haze SIP and FIP (``2011 EPA Oklahoma Regional Haze SIP
TSD''),\48\ and 3.5 years for DSI, citing consistency with the October
2012 Northeastern Regional Haze Settlement Agreement.\49\ Western
Farmers stated that it has no plans to shut down or cease burning coal
at its boiler, and therefore, a remaining useful life of 30 years is
assumed based on information presented in the 2011 EPA Oklahoma
Regional Haze SIP TSD. For energy and non-air quality impacts, Western
Farmers stated that the control options would require increased power
usage, generate solid waste that would need to be managed, require
increased freshwater usage, and/or generate large volumes of wastewater
that would need to be managed. Western Farmers used a 7% interest rate
to calculate the annualized capital costs of each control scenario for
the boiler. According to Western Farmers, estimated cost effectiveness
in dollars per ton of SO<INF>2</INF> removed for WFGD, DFGD, and DSI
for the boiler are $8,462, $8,203, and $41,003, respectively. Based on
the results, Western Farmers concluded that there is no economically
viable control option for the unit. In response to EPA and FLM comments
received on Oklahoma's draft 2022 SIP submission, Oklahoma recalculated
Western Farmer's estimated cost effectiveness for DFGD using a lower
interest rate (3.25% versus the original 7% that Western Farmers used)
and higher control efficiencies (87% to 99% versus 87%) and determined
the lowest estimate to be $6,002 per ton of SO<INF>2</INF> removed. The
Hugo Generating Plant's cost estimates from Western Farmers and
Oklahoma are higher than Oklahoma's determined cost threshold for
SO<INF>2</INF>. Based on these estimates, Oklahoma concurred with
Western Farmer's determination that no additional controls are required
during the second planning period for the Hugo Generating Plant as
controls would not be cost-effective.\50\
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\48\ EPA Technical Support Document for the Oklahoma Regional
Haze State Implementation Plan and Federal Implementation Plan
(``2011 EPA Oklahoma Regional Haze SIP TSD''), March 2011.
\49\ Settlement Agreement between PSO, the Oklahoma Secretary of
Environment, the ODEQ, the EPA, and the Sierra Club, executed on or
about October 17, 2012, available in the docket for this action.
\50\ See Oklahoma's 2022 SIP submission, section 6.4.1.2, p. 40-
41, and appendix E.
---------------------------------------------------------------------------
EPA is proposing to find that the State's determination that no
measures for the Western Farmers Hugo Generating Plant are necessary
for reasonable progress is reasonable and meets regional haze
requirements for the second planning period. In Oklahoma's 2022 SIP
submission, Oklahoma adequately considered the four statutory factors
on the selected control technologies for the boiler at the Western
Farmers Hugo Generating Plant and concluded that no measures are
necessary to make reasonable progress for the second planning period at
the plant. In addition, the projected 2028 visibility conditions at all
Class I areas to which the Western Farmers Hugo Generating Plant
contributes (Wichita Mountains in Oklahoma, Caney Creek and Upper
Buffalo in Arkansas, and Hercules-Glades in Missouri) are below their
respective 2028 URP values. The EPA is proposing to find that Oklahoma
demonstrated that it is making reasonable progress for the second
planning period without requiring any control measures for Western
Farmers Electric Cooperative's Hugo Electric Generating Plant.
iii. Grand River Dam Authority (GRDA)--Grand River Energy Center
(SO<INF>2</INF>)
GRDA's Grand River Energy Center is located in Mayes County and was
identified for analysis for potential SO<INF>2</INF> controls. The GRDA
Grand River Energy Center has one coal-fired boiler (Unit 2) that
reported 629 tons of SO<INF>2</INF> emissions in 2016 and is equipped
with a spray dryer absorber (SDA) designed for a removal efficiency of
85%. Unit 1, which previously emitted 8,358 tons of SO<INF>2</INF>
emissions in 2016, was converted to operate on natural gas and was not
considered for further analysis by Oklahoma. As provided in GRDA's
response to Oklahoma's information collection request, GRDA considered
the following five options for Unit 2: coal washing, circulating dry
scrubbing (CDS), DSI, a new SDA, and WFGD. Coal washing and DSI were
evaluated with the current SDA online, while CDS, new SDA and WFGD were
evaluated with the existing SDA decommissioned. Based on the data
provided by GRDA in its response to Oklahoma, coal washing, and DSI
were estimated to be capable of removing an additional 10% and 50%,
respectively, of SO<INF>2</INF> emissions with the current SDA online.
CDS, new SDA, and WFGD control options would have an estimated control
efficiency of 94%, 94%, and 96% SO<INF>2</INF> removal,
respectively.\51\
---------------------------------------------------------------------------
\51\ See Oklahoma's 2022 SIP submission, section 6.4.1.3, p. 41-
42, and appendix E.
---------------------------------------------------------------------------
GRDA considered the four factors in its response to Oklahoma. For
time necessary for compliance, GRDA estimated implementation times of
1.2 years, 2.5 years, 5.3 years, 5.6 years, and 5.5 years for the coal
washing, CDS, DSI, new SDA, and WFGD control options,
[[Page 6593]]
respectively, applying timeframes for conceptual engineering,
permitting, detailed engineering/procurement, construction, outage
time, and startup and testing. GRDA utilized a different remaining
useful life value from the EPA Control Cost Manual as it anticipates
Unit 2 operating through 2029, stating that while any new system may be
able to operate for 30 years, its operating lifetime will be limited by
the facility's operations. GRDA considered several different energy and
non-air quality impacts for all control options, which included
increased energy demand, increases in some of the monitored parameters,
impacts from mining and transporting the reagent required, increased
water consumption, and increased waste generation. According to GRDA,
estimated cost effectiveness in dollars per ton of SO<INF>2</INF>
removed for coal washing, CDS, DSI, SDA, and WFGD for the boiler are
$126,796, $21,187, $143,321, $176,851 and $140,109, respectively. Based
on the results, GRDA concluded that the control options that are
technically feasible for reducing SO<INF>2</INF> emissions at Unit 2
range in estimated costs from $21,000 to $177,000 per ton of
SO<INF>2</INF> removed, with the estimated total amount of
SO<INF>2</INF> removed ranging from 37 to 294 tons per year. GRDA
therefore concluded and Oklahoma concurred that there are no
economically viable control options for the unit as the cost estimates
are higher than Oklahoma's determined cost threshold for
SO<INF>2</INF>.\52\ Oklahoma also performed some additional cost
calculation for DSI, the lowest cost control option identified by GRDA,
utilizing a remaining useful life of the equipment of 30 years. The
state found that the installation of DSI would still not be considered
cost-effective at a cost of approximately $12,000/ton.
---------------------------------------------------------------------------
\52\ Id.
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EPA is proposing to find that the State's determination that no
measures for the GRDA Grand River Energy Center are necessary for
reasonable progress is reasonable and meets regional haze requirements
for the second planning period. In Oklahoma's 2022 SIP submission,
Oklahoma adequately considered the four statutory factors on the
selected control technologies for the Unit 2 boiler at the GRDA Grand
River Energy Center and concluded that no measures are necessary to
make reasonable progress for the second planning period at the
facility. In addition, the projected 2028 visibility conditions at all
Class I areas to which the GRDA Grand River Energy Center contributes
(Wichita Mountains in Oklahoma, Caney Creek and Upper Buffalo in
Arkansas, and Hercules-Glades in Missouri) are below their respective
2028 URP values. The EPA is proposing to find that Oklahoma
demonstrated that it is making reasonable progress for the second
planning period without requiring any control measures for GRDA's Grand
River Energy Center.
iv. Holcim--Ada Portland Cement Production Plant (SO<INF>2</INF>)
Holcim's Ada Portland Cement Production Plant is located in
Pontotoc County and was selected by Oklahoma for further evaluation of
SO<INF>2</INF> controls. The Holcim Ada Plant had two kilns used in the
production process and reported 2,303 tons of SO<INF>2</INF> emissions
in 2016. In Holcim's response to Oklahoma's information collection
request, Holcim stated that the two kilns that were in operation in
2016 were dismantled and replaced with a new kiln in 2017, with the new
kiln emitting far less SO<INF>2</INF> emissions. Holcim stated that if
more recent emissions data was used, the Ada plant would have fallen
below Oklahoma's selection criteria for the evaluation of
SO<INF>2</INF> controls. According to Oklahoma, the new kiln at
Holcim's Ada Plant emits an estimated 154 tons of SO<INF>2</INF> per
year. Using the data provided by Oklahoma, EPA calculated that the
Holcim Ada Plant's SO<INF>2</INF> emissions have reduced by
approximately 93% since the installation of the new kiln. Due to the
kiln replacement and a significant decrease of SO<INF>2</INF> emissions
at the Holcim Ada Plant, Oklahoma did not analyze the Ada Plant further
for SO<INF>2</INF> emission reductions.<SUP>53 54</SUP>
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\53\ See Oklahoma's 2022 SIP submission, section 6.4.1.4, p. 42,
and appendix E.
\54\ More recent emissions data at the Holcim Ada Plant showed
that the facility emitted 81 tons of SO<INF>2</INF> in 2020 and 94
tons of SO<INF>2</INF> in 2023. See the EPA 2020 National Emission
Inventory data at: <a href="https://www.epa.gov/air-emissions-inventories/2020-national-emissions-inventory-nei-data">https://www.epa.gov/air-emissions-inventories/2020-national-emissions-inventory-nei-data</a>, and ODEQ's 2023 Oklahoma
Annual Point Source Emission Summary at <a href="https://oklahoma.gov/deq/divisions/air-quality/emissions-inventory/state-emissions-totals-infographics.html">https://oklahoma.gov/deq/divisions/air-quality/emissions-inventory/state-emissions-totals-infographics.html</a>.
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EPA is proposing to find that the State's determination for the
Holcim Ada Plant that no measures are necessary for reasonable progress
is reasonable and meets regional haze requirements for the second
planning period. In Oklahoma's 2022 SIP submission, Oklahoma reviewed
more recent facility information at the Holcim Ada Plant and concluded
that no measures are necessary to make reasonable progress for the
second planning period at the plant due to the replacement of the two
kilns with a new kiln. Additionally, the projected 2028 visibility
conditions at Wichita Mountains to which the Holcim Ada Plant
contributes is below its 2028 URP values. The EPA is proposing to find
that Oklahoma demonstrated that it is making reasonable progress for
the second planning period without requiring any control measures for
Holcim's Ada Portland Cement Production Plant.
v. Continental Carbon--Carbon Black Production Facility
(SO<INF>2</INF>)
Continental Carbon's Carbon Black Production Facility is located in
Ponca City, Kay County and was selected by Oklahoma for further
evaluation of SO<INF>2</INF> controls. The Continental Carbon Facility
reported 2,712 tons of SO<INF>2</INF> in 2016, which were primarily
emitted from four carbon black production units controlled by three
thermal oxidizers. Continental Carbon is subject to a federally
enforceable consent decree with EPA, entered on May 7, 2015, and
amended on May 25, 2018, which require the installation of controls for
NO<INF>X</INF> and SO<INF>2</INF> emissions and meet the consent
decree-specified emission limits by April 1, 2021, at the Ponca City
facility.\55\ According to Continental Carbon in its responses to
Oklahoma's information collection requests, the previous SO<INF>2</INF>
control system utilizing the thermal oxidizers for the carbon black
production units was replaced with a dry scrubber system utilizing
scrubbers on two waste gas boilers. Continental Carbon performed an
analysis based on the consent decree requirements to install the dry
scrubber system. Using the original thermal oxidizer control system as
the baseline, which were permitted to emit 5,257 pounds per hour (lb/
hr) of SO<INF>2</INF>, Continental Carbon anticipated an approximate
SO<INF>2</INF> emission reduction of 95% from the installation of the
dry scrubber system, which will have an approximate emission rate of
272 lb/hr, with an approximate reduction of 15,800 tons of
SO<INF>2</INF> emission per year at the facility. Continental Carbon
stated that it expected the dry scrubbers to be operational by the
first quarter of 2021, which coincides with its consent decree deadline
of April 1, 2021, and for the new SO<INF>2</INF> control system to have
a life expectancy of 20 to 25 years. Continental Carbon submitted
details of cost of energy, waste disposal, regulatory requirement,
etc., incurred with implementation of the control measure, as well as
the costs of
[[Page 6594]]
implementing the measure separately as confidential business
information. Recent emissions data show an approximate 92% reduction of
reported SO<INF>2</INF> emissions at the facility from 2016 to 2023,
reflecting the operation of the scrubber system.\56\ Oklahoma stated in
its SIP that it concurs with Continental Carbon's determination that no
further reductions in SO<INF>2</INF> emission, apart from the dry
scrubber system installed at the facility, can be cost-effectively
achieved.\57\
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\55\ Consent Decree between Continental Carbon Company and EPA,
entered May 7, 2015, and amended May 25, 2018, Case No. 5:15-cv-
00290-F, available in the docket for this action.
\56\ Recent emissions data at the Continental Carbon Plant
showed that the facility emitted 214 tons of SO<INF>2</INF> in 2023.
See ODEQ's 2023 Oklahoma Annual Point Source Emission Summary at
<a href="https://oklahoma.gov/deq/divisions/air-quality/emissions-inventory/state-emissions-totals-infographics.html">https://oklahoma.gov/deq/divisions/air-quality/emissions-inventory/state-emissions-totals-infographics.html</a>.
\57\ See Oklahoma's 2022 SIP submission, section 6.4.1.5, p. 42,
and appendix E.
---------------------------------------------------------------------------
EPA is proposing to find that the State's determination for the
Continental Carbon Facility that no measures are necessary for
reasonable progress is reasonable and meets regional haze requirements
for the second planning period. In Oklahoma's 2022 SIP submission,
Oklahoma reviewed recent facility information, consent decree
requirements, and the analysis from the Continental Carbon Facility,
considering potential cost of controls, remaining useful life, time
necessary for compliance, and energy and non-air quality impacts, and
concluded that no measures are necessary to make reasonable progress
for the second planning period at the facility. Additionally, the
projected 2028 visibility conditions at Wichita Mountains to which the
Continental Carbon Facility contributes is below its 2028 URP values.
The EPA is proposing to find that Oklahoma demonstrated that it is
making reasonable progress for the second planning period without
requiring any control measures for Continental Carbon's Carbon Black
Production Facility.
vi. OG&E--Horseshoe Lake Generating Station (NO<INF>X</INF>)
OG&E's Horseshoe Lake Generating Station, an electric generating
station located in Oklahoma County, was selected by Oklahoma for
further evaluation of NO<INF>X</INF> controls. The OG&E Horseshoe Lake
Station utilizes five electric generating units consisting of three
boilers and two turbines and reported 852 tons of NO<INF>X</INF>
emissions in 2016. Three emissions reduction options were considered
for the boilers at the station: selective catalytic reduction (SCR),
selective non-catalytic reduction (SNCR) (only feasible for two of the
boilers), and a combination of combustion technologies, i.e., low-
NO<INF>X</INF> Burners (LNB), overfire air (OFA), and flue gas
recirculation (FGR), together referred to as ``LNB-OFA-FGR'', while
only SCR was considered for the turbines. As provided in OG&E's
response to Oklahoma's information collection request, SCR, SNCR, and
LNB-OFA-FGR would have potential control efficiencies, depending on the
unit, of 90-92%, 30-41%, and 12-41% NO<INF>X</INF> removal,
respectively.\58\
---------------------------------------------------------------------------
\58\ See Oklahoma's 2022 SIP submission, section 6.4.2.1, p. 42,
and appendix E.
---------------------------------------------------------------------------
OG&E considered the four factors in its response to Oklahoma. For
the time necessary for compliance, OG&E estimated a minimum of four
years for implementing SCR and a minimum of two years for implementing
either SNCR or LNB+OFA+FGR at the Horseshoe Lake Station, stating that
implementing controls at multiple units would also increase time
needed. OG&E stated that there are no enforceable limitations on the
remaining useful life on any of the units but explained that due to the
age of the boilers, which have been operating 52 to 62 years, that it
expects those units to operate for 20 years at most. Due to this
reasoning, OG&E utilized a remaining useful life of 20 years for the
boilers and 30 years for the turbines. OG&E considered several
different energy and non-air quality impacts for all control options,
which included increased energy demand, a new waste stream that must be
managed, and increased emissions from unreacted ammonia to the
atmosphere, which may negate some of the calculated visibility
improvements from the anticipated NO<INF>X</INF> reductions. OG&E used
a 7% interest rate to calculate the annualized capital costs of each
control scenario applicable for each unit. According to OG&E, estimated
cost effectiveness in dollars per ton of NO<INF>X</INF> removed for
SCR, SNCR, and LNB-OFA-FGR for the boilers range from $21,537-$26,873,
$24,528-$36,107, and $14,179-$129,391, respectively, while estimated
cost effectiveness for the turbines for SCR are $110,920. OG&E's cost
estimates for Horseshoe Lake Station are higher than Oklahoma's
determined cost threshold for NO<INF>X</INF>. Based on these estimates,
Oklahoma concurred with OG&E's determination that no additional
controls are required during the second planning period for the
Horseshoe Lake Station as controls would not be cost-effective.\59\
Oklahoma also noted in its 2022 SIP submission that the facility is
likely to reduce overall emissions as the unit is subject to CSAPR
NO<INF>X</INF> requirements.
---------------------------------------------------------------------------
\59\ Id.
---------------------------------------------------------------------------
EPA is proposing to find that the State's determination that no
measures for the OG&E Horseshoe Lake Station are necessary for
reasonable progress is reasonable and meets regional haze requirements
for the second planning period. In Oklahoma's 2022 SIP submission,
Oklahoma adequately considered the four statutory factors on the
selected control technologies for the boilers and turbines at the OG&E
Horseshoe Lake Station and concluded that no measures are necessary to
make reasonable progress for the second planning period at the
facility. In addition, the projected 2028 visibility conditions at
Wichita Mountains to which the OG&E Horseshoe Lake Station contributes
is below its 2028 URP values. The EPA is proposing to find that
Oklahoma demonstrated that it is making reasonable progress for the
second planning period without requiring any control measures for
OG&E's Horseshoe Lake Generating Station.
vii. OG&E--Mustang Generating Station (NO<INF>X</INF>)
OG&E's Mustang Generating Station, an electric generating station
located in Canadian County, was selected by Oklahoma for further
evaluation of NO<INF>X</INF> controls. The OG&E Mustang Station
utilized two natural gas fueled electric generating units and reported
747 tons of NO<INF>X</INF> emissions in 2016. These units at Mustang
Station retired on December 31, 2017, as demonstrated in Oklahoma
Operating Permit No. 2018-0555-TVR3, issued August 15, 2018, and
subsequent operating permit modifications and renewals. Recent
emissions data at the facility showed that the OG&E Mustang Station,
after replacing the older units with more modern natural gas fired
turbines, reported 229 tons of NO<INF>X</INF> in 2023, a 69% reduction
in NO<INF>X</INF> emissions compared to 2016 emissions.\60\ Due to the
unit retirements at the OG&E Mustang Station, Oklahoma did not analyze
the facility further for NO<INF>X</INF> emission reductions.\61\
---------------------------------------------------------------------------
\60\ See EPA Clean Air Markets Program Data at <a href="https://campd.epa.gov/">https://campd.epa.gov/</a> and ODEQ's 2023 Oklahoma Annual Point Source Emission
Summary at <a href="https://oklahoma.gov/deq/divisions/air-quality/emissions-inventory/state-emissions-totals-infographics.html">https://oklahoma.gov/deq/divisions/air-quality/emissions-inventory/state-emissions-totals-infographics.html</a>.
\61\ See Oklahoma's 2022 SIP submission, section 6.4.2.2, p. 43,
and appendix E.
---------------------------------------------------------------------------
EPA is proposing to find that the State's determination for the
OG&E Mustang Station that no measures are necessary for reasonable
progress is reasonable and meets regional haze requirements for the
second planning period. In Oklahoma's 2022 SIP submission, Oklahoma
reviewed more
[[Page 6595]]
recent facility information at the OG&E Mustang Station and concluded
that no measures are necessary to make reasonable progress for the
second planning period at the facility. Additionally, the projected
2028 visibility conditions at Wichita Mountains to which the OG&E
Mustang Station contributes is below its 2028 URP values. The EPA is
proposing to find that Oklahoma demonstrated that it is making
reasonable progress for the second planning period without requiring
any control measures for OG&E's Mustang Generating Station.
viii. Mustang Gas--Binger Gas Plant (NO<INF>X</INF>)
Mustang Gas's Binger Gas Plant, located in Caddo County, was
selected by Oklahoma for further evaluation of NO<INF>X</INF> controls.
The Mustang Gas Binger Plant utilizes four natural gas fueled engines,
three of which emitted the majority of the 658 tons of NO<INF>X</INF>
reported at the plant in 2016. As provided in Mustang Gas's response to
Oklahoma's information collection request, three of the engines already
operate with air fuel ratio controllers (AFRC) installed, and two of
the engines operate with non-selective catalytic reduction (NSCR)
installed, and therefore only NSCR was considered for the remaining two
engines. Mustang Gas expects a potential NO<INF>X</INF> control
efficiency of 90%, as this has already been demonstrated based on
recent testing in comparison to the uncontrolled manufactured
specifications for these engines.\62\
---------------------------------------------------------------------------
\62\ See Oklahoma's 2022 SIP submission, section 6.4.2.3, p. 43,
and appendix E.
---------------------------------------------------------------------------
Mustang Gas considered the four factors in its response to
Oklahoma. Mustang Gas estimated two years for implementing NSCR at the
units, accounting for the budget, design, procurement, authorization,
and installation of the control systems. Mustang Gas also estimated a
remaining useful life of 20 years for the NSCR equipment, based on
default values from the EPA Control Cost Manual, but also noted the
need to change the catalyst beds approximately every two years based on
operational hours and best engineering practices. For energy and non-
air quality impacts, Mustang Gas stated the use of NSCR on the engines
would require increased energy consumption as well as periodic
replacement and disposal of the catalyst. According to Mustang Gas,
estimated cost effectiveness in dollars per ton of NO<INF>X</INF>
removed for NSCR at the two engines would cost $24.00 and $24.67, which
was considered cost effective. Mustang Gas and Oklahoma concurred that
the use of NSCR with good combustion practices was the most efficient
control application for the two engines at the plant that do not
already have NSCR installed, and further controls beyond installation
of NSCR are not necessary. Mustang Gas completed installation of NSCR
at one of the engines and committed to installing NSCR at the other
engine, planning to have it operational by a year after Oklahoma's 2022
SIP submission is approved by EPA. Consistent with this requirement in
the SIP, Mustang Gas signed an agreement with ODEQ on January 15, 2026,
(``Mustang Gas Regional Haze Agreement''), which stated that Mustang
Gas will install NSCR at the remaining engine within one year after
EPA's approval of Oklahoma's 2022 SIP submission.\63\ As stated in the
Mustang Gas Regional Haze Agreement and as Oklahoma stated in its SIP,
Mustang Gas Binger Plant engine's controls will be added to the
facility's permit and include updated NO<INF>X</INF> emission limits
(9.00 grams NO<INF>X</INF> per horsepower-hour and 104.29 tons
NO<INF>X</INF> per year) as well as the provided testing, monitoring,
reporting and recordkeeping requirements.\64\
---------------------------------------------------------------------------
\63\ Regional Haze Agreement between Mustang Gas Products,
L.L.C., Binger Gas Plant and Oklahoma Department of Environmental
Quality Air Quality Division, Case No. 26-008, effective January 15,
2026, received by EPA on January 20, 2026, available in Oklahoma's
2022 SIP submission.
\64\ See Oklahoma's 2022 SIP submission, section 6.4.2.3, p. 43,
section 6.9, p. 51, appendix E, and the Mustang Gas Regional Haze
Agreement.
---------------------------------------------------------------------------
EPA is proposing to find that the State's determination for the
Mustang Gas Binger Plant is reasonable and meets regional haze
requirements for the second planning period. In Oklahoma's 2022 SIP
submission, Oklahoma adequately considered the four statutory factors
on the selected control technologies for the engines at the Mustang Gas
Binger Plant to come to its conclusion to require NSCR at the remaining
engine that already does not have NSCR installed. EPA is proposing to
find that Oklahoma's determination of requiring installation of NSCR at
the remaining engine as part of Oklahoma's long-term strategy for the
second planning period is reasonable and demonstrates reasonable
progress for the second planning period. EPA is proposing to approve
the Mustang Gas Regional Haze Agreement, Case No. 26-008, as a source-
specific SIP requirement for the Binger Gas Plant.
ix. ONEOK--Lindsay Booster Station (NO<INF>X</INF>)
ONEOK's Lindsay Booster Station in Garvin County was selected by
Oklahoma for further evaluation of NO<INF>X</INF> controls. The ONEOK
Lindsay Station utilized eight natural gas fueled compression engines
which emitted the majority of the 928 tons of NO<INF>X</INF> reported
at the station in 2016. ONEOK removed and replaced the eight natural
gas fueled engines with electric compression units, as demonstrated
under General Permit for Oil and Gas General Facilities Authorization
to Operate No. 2019-0758-O, issued on May 5, 2020, and Lindsay Station
is no longer considered a title V source. Recent emissions data at the
facility showed that the ONEOK Lindsay Station reported 8 tons of
NO<INF>X</INF> in 2023, a 99% reduction in NO<INF>X</INF> emissions
compared to 2016 emissions.\65\ Due to the unit replacements at the
ONEOK Lindsay Station, Oklahoma did not analyze the facility further
for NO<INF>X</INF> emission reductions.\66\
---------------------------------------------------------------------------
\65\ See ODEQ's 2023 Oklahoma Annual Point Source Emission
Summary at <a href="https://oklahoma.gov/deq/divisions/air-quality/emissions-inventory/state-emissions-totals-infographics.html">https://oklahoma.gov/deq/divisions/air-quality/emissions-inventory/state-emissions-totals-infographics.html</a>.
\66\ See Oklahoma's 2022 SIP submission, section 6.4.2.4, p. 43.
---------------------------------------------------------------------------
EPA is proposing to find that the State's determination for the
ONEOK Lindsay Station that no measures are necessary for reasonable
progress is reasonable and meets regional haze requirements for the
second planning period. In Oklahoma's 2022 SIP submission, Oklahoma
reviewed more recent facility information at the ONEOK Lindsay Station
and concluded that no measures are necessary to make reasonable
progress for the second planning period at the facility. As the ONEOK
Lindsay Station's previous natural gas fueled compression engines have
been replaced with electric compression engines, the NO<INF>X</INF>
emissions at the facility have significantly decreased. The EPA is
proposing to find that Oklahoma demonstrated that it is making
reasonable progress for the second planning period without requiring
any control measures for ONEOK's Lindsay Booster Station.
x. ONEOK--Maysville Gas Plant (NO<INF>X</INF>)
ONEOK's Maysville Gas Plant in Garvin County was selected by
Oklahoma for further evaluation of NO<INF>X</INF> controls. The ONEOK
Maysville Plant utilized thirteen natural gas fueled compression
engines which emitted the majority of the 1,093 tons of NO<INF>X</INF>
reported at the plant in 2016. ONEOK retired seven of the thirteen
natural gas fueled engines and plans to retire the remaining six
engines before the end of the second planning period. These older
engines have been used for natural gas
[[Page 6596]]
compression and are planned to be or have already been replaced with
electric compression in lieu of natural gas as part of the gas plant's
operations. ONEOK signed an agreement with ODEQ on May 6, 2022,
(``ONEOK Regional Haze Agreement''), which stated that ONEOK will
remove from service the remaining six engines and incorporate the
removal into its permits for the Maysville Plant by December 31, 2028,
in lieu of performing a four-factor analysis.\67\ Due to the engines
that have already been removed and engines planned to be removed as
part of the ONEOK Regional Haze Agreement at the ONEOK Maysville Gas
Plant, Oklahoma did not analyze the facility further for NO<INF>X</INF>
emission reductions.\68\
---------------------------------------------------------------------------
\67\ Regional Haze Agreement between ONEOK Field Services,
L.L.C., Maysville Gas Plant and Oklahoma Department of Environmental
Quality Air Quality Division, Case No. 22-085 May 6, 2022, available
in Oklahoma's 2022 SIP submission, appendix F.
\68\ See Oklahoma's 2022 SIP submission, section 6.4.2.5, p. 43-
44, and appendix F.
---------------------------------------------------------------------------
EPA is proposing to find that the State's determination for the
ONEOK's Maysville Gas Plant is reasonable and meets regional haze
requirements for the second planning period. In Oklahoma's 2022 SIP
submission, Oklahoma submitted as part of the SIP submission, the
enforceable mechanism the ONEOK Regional Haze Agreement, which requires
the removal of the remaining six engines at the Maysville Plant by the
end of the second planning period. EPA is proposing to find that
removal of the remaining engines at the ONEOK's Maysville Gas Plant as
part of Oklahoma's long-term strategy for the second planning period is
reasonable and demonstrates reasonable progress for the second planning
period. EPA is proposing to approve the ONEOK Regional Haze Agreement,
Case No. 22-085, as a source-specific SIP requirement for the Maysville
Gas Plant.
xi. Panhandle Eastern Pipeline--Cashion Compressor Station
(NO<INF>X</INF>)
Panhandle Eastern Pipeline's Cashion Compressor Station was
selected by Oklahoma for further evaluation of NO<INF>X</INF> controls.
The Panhandle Eastern Cashion Station utilized four natural gas fueled
compression engines and reported 759 tons of NO<INF>X</INF> emissions
in 2016. In Panhandle Eastern's response to Oklahoma's information
collection request, Panhandle Eastern stated that emissions were
previously reported using the facility's potential to emit, which were
overly conservative and not representative of actual emissions at the
facility,\69\ and provided updated facility data and calculations,
including engine testing data that demonstrated more accurate actual
emissions from the engines. According to Panhandle Eastern, based on
the engine testing data conducted using its Federal Energy Regulatory
Commission limited horsepower (instead of the permitted horsepower
rating and permit factors which were previously used), NO<INF>X</INF>
emissions from the two engines are 200 tons per year at maximum, and if
these values had been used instead of its previously reported values,
the Cashion Station would have fallen below Oklahoma's selection
criteria for the evaluation of NO<INF>X</INF> controls.\70\ In its
submitted analysis, Panhandle Eastern evaluated potential control
scenarios for its four engines but due to the potential for technical
difficulties in applying and operating control devices and technology
on these engines, the analysis concluded that adding controls was
infeasible.\71\
---------------------------------------------------------------------------
\69\ Oklahoma and Panhandle Eastern state that the previous
emissions reported were not based on the Federal Energy Regulatory
Commission limited horsepower, the permitted maximum operating hours
allowed, or on portable emission analyzer engine test data.
\70\ The Q/d would have been calculated as 3.2 tons per year per
km compared to the selection threshold of 5.
\71\ See Oklahoma's 2022 SIP submission, section 6.4.2.6, p. 44,
and appendix E.
---------------------------------------------------------------------------
EPA is proposing to find that the State's determination for the
Panhandle Eastern Cashion Station that no measures are necessary for
reasonable progress is reasonable and meets regional haze requirements
for the second planning period. In Oklahoma's 2022 SIP submission,
Oklahoma reviewed more recent facility information at the Panhandle
Eastern Cashion Station, including consideration that had the actual
emissions data been used when selecting sources for four-factor
analysis the facility would not have been identified for additional
analysis in the source-selection process, and concluded that no
measures are necessary to make reasonable progress for the second
planning period at the station. Additionally, the projected 2028
visibility conditions at Wichita Mountains to which the Panhandle
Eastern Cashion Station could contribute to is below its 2028 URP
values. The EPA is proposing to find that Oklahoma demonstrated that it
is making reasonable progress for the second planning period without
requiring any control measures for Panhandle Eastern Pipeline's Cashion
Compressor Station.
xii. DCP Operating--Chitwood Gas Plant (NO<INF>X</INF>)
DCP Operating's Chitwood Gas Plant in Grady County was selected by
Oklahoma for further evaluation of NO<INF>X</INF> controls. According
to the Oklahoma's 2022 SIP submission, the DCP Chitwood Plant utilizes
eight natural gas fueled engines that emitted the majority of the 766
tons of NO<INF>X</INF> reported at the plant in 2016. As provided in
DCP's response to Oklahoma's information collection request, as the
engines already operate with good combustion practices, DCP considered
SCR and clean burn technology (CBT) as potential controls. DCP provided
two separate CBT options, one that reduced emissions to 6 grams per
horsepower-hour (CBT-6g) and one that reduced emissions to 1 gram per
horsepower-hour (CBT-1g) and deemed SCR as only technically feasible in
conjunction with CBT as it would help stabilize the outlet emissions
and combustion. DCP anticipated that the addition of SCR to CBT-6g
would have a similar emissions reduction as CBT-1g, although spacing
limitations for the addition of SCR controls on these existing units
may still make this option not technically feasible. The three control
scenarios that DCP evaluated were CBT-6g, CBT-1g, and SCR in
conjunction with CBT-1g (SCR-CBT) with estimated control efficiencies
ranging from 46-57%, 91-93%, and 91-93% for each control scenario,
respectively.\72\
---------------------------------------------------------------------------
\72\ See Oklahoma's 2022 SIP submission, section 6.4.2.7, p. 44-
45, and appendix E.
---------------------------------------------------------------------------
DCP considered the four factors in its response to Oklahoma. DCP
estimated a minimum of five years would be needed for implementing all
of the controls, taking into account the need to stagger the
implementation of controls for multiple engines so that only one engine
is down at a time. DCP stated that it has no plans to retire the
affected units aside from one at the Chitwood Plant and therefore a
remaining useful life value of 30 years is assumed for SCR and CBT
based on guidance in the EPA Control Cost Manual. For energy and non-
air quality impacts, DCP stated that SCR would lead to increased
electricity demand, a new solid waste stream that must be managed,
require storage of large amounts of ammonia or urea, and increased
emissions from unreacted ammonia to the atmosphere, which may negate
some of the calculated visibility improvements from the anticipated
NO<INF>X</INF> reductions. DCP used a 7% interest rate to calculate the
annualized capital costs of each control scenario for each engine.
According to DCP, estimated cost
[[Page 6597]]
effectiveness in dollars per ton of NO<INF>X</INF> removed for CBT-6g,
CBT-1g, and SCR-CBT for the engines range from $4,366-$20,186, $3,250-
$15,917, and $3,293-$16,909. In response to comments received on
Oklahoma's draft 2022 SIP submission, Oklahoma recalculated DCP's
estimated cost effectiveness using a lower interest rate (3.25% versus
the original 7% that DCP used) and determined the lowest estimate to be
$2,400 per ton of NO<INF>X</INF> removed. DCP's and Oklahoma's cost
estimates for the Chitwood Plant are higher than Oklahoma's determined
cost threshold for NO<INF>X</INF>. Oklahoma concurred with DCP's
determination that no additional controls are required during the
second planning period for the Chitwood Plant as controls would not be
cost-effective.\73\
---------------------------------------------------------------------------
\73\ Id.
---------------------------------------------------------------------------
EPA is proposing to find that the State's determination that no
measures for the DCP Chitwood Plant are necessary for reasonable
progress is reasonable and meets regional haze requirements for the
second planning period. In Oklahoma's 2022 SIP submission, Oklahoma
considered the four statutory factors on the selected control
technologies for the boiler at the DCP Chitwood Plant and concluded
that no measures are necessary to make reasonable progress for the
second planning period at the plant. In addition, the projected 2028
visibility conditions at Wichita Mountains to which the DCP Chitwood
Plant contributes is below its 2028 URP values. The EPA is proposing to
find that Oklahoma demonstrated that it is making reasonable progress
for the second planning period without requiring any control measures
for DCP Operating's Chitwood Gas Plant.
xiii. Conclusion
Under 40 CFR 51.308(f)(2)(iii), the state must describe the
criteria used to determine which sources were evaluated 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 as part of its reasonable progress
determinations. As discussed in sections IV.C.1.a and b as well as
sections IV.C.2.b.i through xii of this document, Oklahoma provided its
source selection methodology in detail, selected twelve sources (five
NO<INF>X</INF> sources and seven SO<INF>2</INF> sources) for evaluation
based on its methodology, and performed a four-factor analysis on the
selected sources. Oklahoma considered the four factors when evaluating
emission reduction measures for inclusion in its long-term strategy. A
summary of Oklahoma's four-factor analysis results is provided in table
6-4 of Oklahoma's 2022 SIP submission. The measures Oklahoma determined
to be necessary for reasonable progress are part of its long-term
strategy. As discussed in further detail in section IV.C.1.b and
sections IV.C.2.b.vi through xii of this document, Oklahoma's long-term
strategy includes source-specific NO<INF>X</INF> control measures,
which include a commitment to remove the remaining engines at ONEOK
Maysville Gas Plant and installation of additional controls at the
Mustang Gas Binger Gas Plant. As required under 40 CFR 51.308(f)(2)(iv)
and discussed in section IV.C.3 of this document, Oklahoma considered
the five additional factors when developing Oklahoma's long-term
strategy. Other parts of Oklahoma's long-term term strategy include
ongoing air pollution control programs, measures for smoke management,
and reducing impacts from construction activities.
See section IV.B of this document for a discussion of current
visibility conditions as well as URP for the second planning period in
Oklahoma's Class I area, Wichita Mountains. See section IV.D of this
document for Oklahoma's 2028 RPGs and comparison to visibility
conditions and the URP at Wichita Mountains as well as the RPGs and
URPs of Class I areas potentially affected by Oklahoma sources. EPA's
2028 modeling shows that the 2028 projections for the 20 percent most
impaired days (16.93 deciviews) are less than the URP (17.36 deciviews)
\74\ at Wichita Mountains.
---------------------------------------------------------------------------
\74\ After adjusting for wildland fires and international
contributions.
---------------------------------------------------------------------------
Because (1) Oklahoma considered the four statutory factors in the
assessment of the potential for additional controls to make reasonable
progress and (2) the projected 2028 visibility conditions for Class I
areas influenced by emissions from Oklahoma sources are all below the
URP, the EPA finds that Oklahoma has demonstrated that it has made
reasonable progress towards the national visibility goal for the second
planning period. Therefore, we are proposing to approve Oklahoma's 2022
SIP submission as meeting the CAA and regulatory requirement to make
reasonable progress towards the national visibility goal, including
requirements under CAA section 169A(g)(1) and 40 CFR 51.308(f)(2)(i).
3. Other Long-Term Strategy Requirements (40 CFR 51.308(f)(2)(ii)
Through (iv))
States must meet the additional requirements specified in 40 CFR
51.308(f)(2)(ii) through (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. Section 8.1: Direct State-
to-State Consultation of Oklahoma's 2022 SIP submission, which also
refers back to section 6.5: State consultation for sources identified
with potential contribution and 6.6: Class I areas potentially impacted
by Oklahoma sources of the SIP, describes the State's consultation with
other states throughout the development of its regional haze plan.
Oklahoma is a member of CenSARA and participated in CenSARA led monthly
conference calls with representatives of member states, FLMs, and other
organizations from 2019 through 2022. Oklahoma participated in this
process as part of ongoing consultation between states and federal
partners, including FLMs. Oklahoma separately consulted directly with
Texas, Arkansas, Missouri, Louisiana, and Nebraska regarding sources in
those states identified with potential contributions to visibility
impairment at Wichita Mountains, and any Oklahoma sources identified
with potential contributions to visibility impairment to Class I areas
in those states.\75\ Using the same methodology described in Section
IV.C.1.a, Oklahoma identified 19 sources outside Oklahoma that are
reasonably anticipated to contribute to visibility impairment at
Wichita Mountains. Table 6-5 of Oklahoma's 2022 SIP submission
summarizes the sources that Oklahoma requested each state to consider
for further analysis and the outcome of any analysis provided by the
states. Table 6-6 of Oklahoma's 2022 SIP submission summarizes the
Oklahoma sources identified for potential impacts in Class I areas in
other states (Caney Creek Wilderness Area and Upper Buffalo Wilderness
Area in Arkansas and Hercules-Glades Wilderness Area in Missouri) and
the result of the Oklahoma's consideration of those sources. EPA is
proposing to find that DEQ has satisfied the consultation requirement
of 40 CFR 51.308(f)(2)(ii) in its 2022 Planning Period II SIP. No
[[Page 6598]]
states disagreed with the Oklahoma proposed measures necessary for
reasonable progress for the second implementation period and no other
measures were identified or agreed upon by the other states for
Oklahoma to include in its SIP.
---------------------------------------------------------------------------
\75\ See Oklahoma's 2022 SIP submission, appendix A for details
of the consultation process.
---------------------------------------------------------------------------
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. The State may meet
this requirement by relying on technical analyses developed by an RPO,
as long as the process has been approved by all State participants.
Section 51.308(f)(2)(iii) also requires that the emission information
considered to determine the measures that are necessary to make
reasonable progress include information on emissions for the most
recent year for which the State has submitted triennial emissions data
to the EPA (or a more recent year), with a 12-month exemption period
for newly submitted data. Sections 3: Visibility Monitoring, 4:
Emission Trends, and 6: 2018-2028: Planning Period 2 of Oklahoma's 2022
SIP submission describe the technical information on which the State
relied. The State relied on IMPROVE monitoring data, National Emissions
Inventory data, as well as EPA and CenSARA technical information,
modeling, and analysis to support development of its long-term
strategy. All documentation that the State is relying on to determine
the emission reduction measures necessary to make reasonable progress
were included in the SIP submission in the various appendices. Oklahoma
included an AOI analysis performed by Ramboll for the CenSARA states in
its 2022 SIP submission to identify sources within Oklahoma with the
potential for impairing visibility at the Wichita Mountains and Class I
areas in neighboring states.\76\ Oklahoma evaluated four-factor
analysis reports from the sources brought forward for potential
controls analysis which included cost and emission reduction
calculations.\77\ Under Sections 4: Emission Trends, Oklahoma included
point, non-point, non-road, on-road, and biogenic statewide emissions
for VOC, NO<INF>X</INF>, PM, NH<INF>3</INF> and SO<INF>2</INF> for the
years 2002, 2011, and 2017. Oklahoma included 2017 emissions
information as the 2020 National Emissions Inventory (NEI) data had not
been released by EPA yet at the time the report was generated. The EPA
is proposing to find that Oklahoma has satisfied the requirements of 40
CFR 51.308(f)(2)(iii) in its 2022 SIP submission. Based on the
documentation provided by the State, Oklahoma has demonstrated the
technical bases and emission information on which it is relying to
determine the emission reductions measures that are necessary to make
reasonable progress for its long-term strategy for the second planning
period.
---------------------------------------------------------------------------
\76\ See Oklahoma's 2022 SIP submission, appendices B through D,
for the AOI analyses and source selection methodology.
\77\ See Oklahoma's 2022 SIP submission, appendix E for the
four-factor analyses.
---------------------------------------------------------------------------
40 CFR 51.308(f)(2)(iv) specifies five additional factors states
must consider in developing their long-term strategies. As mentioned,
the five additional factors for consideration in section
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. The five
additional factors are: (1) emission reductions due to ongoing air
pollution control programs, including measures to address reasonably
attributable visibility impairment; (2) measures to mitigate 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 following sections from Oklahoma's 2022 SIP
submission describes each of the five additional factors: section 6.9.
Long-term strategy, section 6.9.1: Ongoing air pollution control
programs, section 6.9.3: Construction Activities, section 6.7: Facility
Closures and Unit Shutdowns, 6.9.2: Smoke Management, and section 4:
Emission Trends.
40 CFR 51.308(f)(2)(iv)(A) requires states to consider emission
reductions due to ongoing air pollution control programs, including
measures to address reasonably attributable visibility impairment.
Section 6.9.1 of Oklahoma's 2022 SIP submission discusses Oklahoma's
ongoing air pollution control programs as part of its long-term
strategy. These ongoing air pollution control programs include
Oklahoma's major source and minor facility permitting program and
enforcement program, implementation of federal rules such as the NSPS
containing emission and equipment standards, and programs approved in
Oklahoma's SIP designed to address National Ambient Air Quality
Standards (NAAQS) requirements. In addition, Oklahoma states that a
number of Oklahoma emission sources are subject to the CSAPR and other
federal rules that reduce emissions.
40 CFR 51.308(f)(2)(iv)(B) requires states to consider measures to
mitigate the impacts of construction activities. Section 6.9.3 of
Oklahoma's 2022 SIP submission discusses how Oklahoma addresses this
requirement. Oklahoma states that it implements State regulations at
Oklahoma Administrative Code (OAC) Title 252, Chapter 100, Subchapter
29 (OAC 252:100-29), Control of fugitive dust, to minimize air quality
degradation from windblown dust from regulated activities such as
construction activities that may stir fugitive dust that reasonably may
impair visibility. The provisions of OAC 252:100-29 are approved into
Oklahoma's SIP and are part of Oklahoma's long-term strategy.
40 CFR 51.308(f)(2)(iv)(C) requires states to consider source
retirement and replacement schedules. Section 6.7 of Oklahoma's 2022
SIP submission discusses facility closures and unit shutdowns. Oklahoma
states that multiple Oklahoma facilities have made major changes to
their operations, resulting in considerable emission reductions. This
information is provided in sections 6.4 and 6.9 in its SIP. In
addition, Texas facilities such as Big Brown and Monticello coal-fired
power plants, which previously reported emissions of 20,000 tons of
SO<INF>2</INF> per year, have since closed and Sandow, another power
plant, shut down two of its coal-fired units. These facilities were
significant contributors to visibility impairment at the Wichita
Mountains. As discussed in section 6.4 of its 2020 SIP submission,
Oklahoma took into account as part of its four-factor analysis and
long-term strategy considerations Oklahoma facilities that have planned
or have already retired or replaced older units. These facilities, also
discussed in section IV.C.2.b of this document, include Holcim's Ada
Portland Cement Production Plant, Continental Carbon's Carbon Black
Production Facility, OG&E's Mustang Generating Station, ONEOK's Lindsay
Booster Station, and ONEOK's Maysville Gas Plant. Oklahoma notes that
these developments have resulted in visibility improvements.
40 CFR 51.308(f)(2)(iv)(D) requires states to consider basic smoke
management practices for prescribed fire used for agricultural and
wildland vegetation management purposes, and smoke management programs.
Section
[[Page 6599]]
6.9.2 of Oklahoma's 2022 SIP submission discusses how Oklahoma
addresses this requirement. Oklahoma states that in coordination with
Oklahoma Department of Agriculture, Food, and Forestry it has adopted
and updated in 2021 a smoke management plan to minimize air-quality
effects of smoke from prescribed burning.\78\
---------------------------------------------------------------------------
\78\ See Oklahoma's 2022 SIP submission, appendix G, ``Oklahoma
Smoke Management Plan''. See also <a href="https://www.deq.ok.gov/air-quality-division/smoke-management/">https://www.deq.ok.gov/air-quality-division/smoke-management/</a>.
---------------------------------------------------------------------------
40 CFR 51.308(f)(2)(iv)(E) requires states to consider 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. Oklahoma utilized photochemical modeling to project
visibility in Wichita Mountains in 2028 which took into account
estimated projected source sector contributions. Oklahoma compared
photochemical modeling conducted by EPA, the Western Regional Air
Partnership (WRAP) contracted with Ramboll-Environ, and the Visibility
Improvement State and Tribal Association of the Southeast (VISTAS)
contracted with the Eastern Research Group (ERG) for the 20 percent
most impaired days at Wichita Mountains. Oklahoma took its URP for the
second planning period from EPA's 2028 modeling projections. Oklahoma
states in its SIP that the URP line illustrates the progress Oklahoma
has made and continues to make. See sections IV.B and IV.D of this
document for a discussion of Oklahoma's URP and RPG.
The EPA is proposing to find that Oklahoma has met the requirements
of 40 CFR 51.308(f)(2)(iv) in its 2022 SIP submission by reasonably
considering the five ``additional factors'' in developing its long-term
strategy for the second implementation period. Oklahoma adequately
considered emission reductions due to ongoing air pollution control
programs; measures to mitigate impacts of construction activities;
source retirements and replacement schedules; smoke management
practices and programs; and anticipated visibility conditions in 2028
resulting from implementation of its long-term strategy.
After reviewing Oklahoma's 2022 SIP chapters addressing 40 CFR
51.308(f)(2)(ii) through (iv), the EPA finds that Oklahoma has
satisfied the long-term strategy requirements of 40 CFR
51.308(f)(2)(ii) through (iv).
D. Reasonable Progress Goals
Section 51.308(f)(3) contains the requirements pertaining to RPGs
for each Class I area. 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) to be in states' long-term
strategies, as well as implementation of other CAA requirements. The
long-term strategies as reflected by the RPGs must provide for an
improvement in visibility on the most impaired days relative to the
baseline period and ensure no degradation on the clearest days relative
to the baseline period. Section 51.308(f)(3)(ii) applies in
circumstances in which a Class I area's RPG for the most impaired days
represents a slower rate of visibility improvement than the uniform
rate of progress calculated under 40 CFR 51.308(f)(1)(vi). Under 40 CFR
51.308(f)(3)(ii)(A), if the state in which a mandatory Class I area is
located establishes an RPG for the most impaired days that provides for
a slower rate of visibility improvement than the URP, the state must
demonstrate that there are no additional emission reduction measures
for anthropogenic sources or groups of sources in the state that would
be reasonable to include in its long-term strategy. Section
51.308(f)(3)(ii)(B) requires that if a state contains sources that are
reasonably anticipated to contribute to visibility impairment in a
Class I area in another state, and the RPG for the most impaired days
in that Class I area is above the URP, the upwind state must provide
the same demonstration.
Oklahoma discusses how its SIP meets reasonable progress goal
requirements in section 7 of its 2022 SIP submission. Oklahoma
developed reasonable progress goals for Wichita Mountains for the 20
percent most impaired days and 20 percent clearest days based on EPA's
2028 modeling for regional haze.\79\ This information, taken from table
7-1 and other sections of Oklahoma's 2022 SIP submission, is provided
in table 4.
---------------------------------------------------------------------------
\79\ See Oklahoma's 2022 SIP submission, p. 50-53.
Table 4--Visibility Conditions and Metrics for Wichita Mountains
----------------------------------------------------------------------------------------------------------------
20% Clearest days 20% Most impaired days
Metric (deciviews) (deciviews)
----------------------------------------------------------------------------------------------------------------
Baseline (2000-2004)............................................ 9.92 22.18
Current (2015-2019)............................................. 8.65 17.58
2028 Reasonable Progress Goal (RPG)............................. 8.14 16.93
2028 Uniform Rate of Progress (URP)............................. ................... * 17.36
Natural Conditions (2064)....................................... 4.20 * 10.19
----------------------------------------------------------------------------------------------------------------
* Adjusted for wildland prescribed fires and international contributions.
As discussed in section IV.B of this document, Oklahoma determined
the URP for Wichita Mountains for the 20 percent most impaired days in
2028 to be 17.36 deciviews after adjusting for contributions from
international emissions and wildland prescribed fires. Oklahoma's 2028
RPG for Wichita Mountains for the 20 percent most impaired days (16.93
deciviews) is 0.43 deciviews less than its URP for the 20 percent most
impaired days (17.36 deciviews). Oklahoma's RPG, taken from 2028 future
projections on EPA's 2028 modeling, is based on ambient IMPROVE data
from 2014-2017 and incorporates Oklahoma's long-term strategy described
in its 2022 SIP submission. In addition, Oklahoma's RPGs provide for an
improvement in visibility for the 20 percent most impaired days since
the 2000-2004 baseline period and demonstrate that there is no
degradation in visibility for the 20 percent clearest days since the
baseline period.
As Oklahoma's RPG is below the glidepath value (URP), the
demonstration requirement under section 51.308(f)(3)(ii)(A) is not
triggered. For the three Class I areas outside the State identified as
having potential visibility impacts from Oklahoma emission sources,
Caney Creek Wilderness Area and Upper Buffalo Wilderness Area in
Arkansas
[[Page 6600]]
and Hercules-Glades Wilderness Area in Missouri, all three of these
Class I areas had 2028 RPGs below their respective URPs.\80\ Therefore,
the demonstration requirement under section 51.308(f)(3)(ii)(B) is also
not triggered. We also note that EPA's 2028 modeling projected 2028
visibility to be lower than the 2028 unadjusted glidepath for the 20
percent most impaired days for all three out-of-state Class I areas.
This information is provided in table 5.
---------------------------------------------------------------------------
\80\ See Arkansas's August 8, 2022, Regional Haze 2md Planning
Period submittal in docket EPA-R06-OAR-2022-0735 and Missouri's
August 26, 2022, Regional Haze 2md Planning Period submittal in
docket EPA-R07-OAR-2024-0286.
Table 5--Visibility Projections for Class I Areas Outside of Oklahoma Potentially Impacted by Oklahoma Sources
--------------------------------------------------------------------------------------------------------------------------------------------------------
EPA's 2028
EPA's 2028 modeling-- modeling--2028
State's RPG for State's 2028 2028 projected 20% unadjusted
Class I area name State the 20% most Uniform Rate of most impaired days glidepath 20%
impaired days Progress (URP) (deciviews) most impaired
(deciviews) (deciviews) days
(deciviews)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Caney Creek Wilderness.................... Arkansas.................... 16.31 18.90 16.97 18.18
Upper Buffalo Wilderness.................. Arkansas.................... 16.49 19.26 16.92 18.32
Hercules-Glades Wilderness................ Missouri.................... 17.44 18.82 17.44 18.82
--------------------------------------------------------------------------------------------------------------------------------------------------------
Based on the information in this section of this document, EPA
proposes to find that Oklahoma has satisfied the applicable
requirements of 40 CFR 51.308(f)(3) relating to RPGs.
E. Reasonably Attributable Visibility Impairment
The RHR contains a requirement at 40 CFR 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,'' \81\ 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 the
State to that effect; nor did the State indicate that FLMs for Wichita
Mountains identified any RAVI from Oklahoma sources. For this reason,
the EPA proposes to approve the portions of Oklahoma's 2022 SIP
submission relating to 40 CFR 51.308(f)(4).
---------------------------------------------------------------------------
\81\ 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. Monitoring Strategy and Other State 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 IMPROVE
network.
Under 40 CFR 51.308(f)(6)(i), States must provide for the
establishment of 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. For states with Class I areas (including Oklahoma), 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. Section 51.308(f)(6)(iii) does not apply to
Oklahoma, as it has a Class I area. 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. Section 51.308(f)(6)(v) requires SIPs to provide for a statewide
inventory of emissions of pollutants that are reasonably anticipated to
cause or contribute to visibility impairment, including emissions for
the most recent year for which data are available. Section
51.308(f)(6)(v) also requires states to include estimates of future
projected emissions. Finally, 40 CFR 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.
Oklahoma discusses its monitoring strategy and its participation in
the IMPROVE network in section 3: Visibility Monitoring of its 2022 SIP
submission. The IMPROVE monitor in Wichita Mountains was established in
2001 and addresses RHR monitoring requirements for Oklahoma. Oklahoma's
monitoring strategy continues to rely upon participation in the IMPROVE
network, and it relies on IMPROVE monitor data to assess visibility
conditions and reasonable progress in Wichita Mountains, the Class I
area in Oklahoma.\82\ The IMPROVE monitoring data, including data at
Wichita Mountains, is provided directly to the EPA and is available at
EPA's Air Quality System (AQS) database.
---------------------------------------------------------------------------
\82\ See Oklahoma's 2022 SIP submission, p. 7-8.
---------------------------------------------------------------------------
In section 6.2 of its 2022 SIP submission, Oklahoma describes the
procedures used to determine the contribution of in-State emissions to
Class I areas inside and outside Oklahoma using the IMPROVE monitoring
data and other information.\83\ In addition, while discussing emission
trends in section 4 of its 2022 SIP submission, the State also provided
2002, 2011 and 2017 emission inventory summaries for the following
pollutants: VOC, NO<INF>X</INF>, PM, NH<INF>3</INF> and
SO<INF>2</INF>.\84\ Oklahoma used projected emissions data (from EPA
and RPOs' model projections) as part of its procedure in establishing
RPGs for Wichita Mountains.\85\
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\83\ See Oklahoma's 2022 SIP submission, p. 29-35; appendix B.
\84\ See Oklahoma's 2022 SIP submission, p. 17-22. According to
the SIP, at the time ODEQ's report was generated, 2017 was still the
most recent complete National Emissions Inventory (NEI) data year
available as the 2020 NEI data had not been released by EPA yet.
\85\ See Oklahoma's 2022 SIP submission, p. 50-51.
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[[Page 6601]]
The EPA finds that Oklahoma has met the requirements of 40 CFR
51.308(f)(6), including through its continued participation in the
IMPROVE network and CenSARA RPO and its ongoing compliance with the Air
Emissions Reporting Requirements (AERR). There is no indication that
further SIP elements are necessary at this time for Oklahoma to assess
and report on visibility. Therefore, the EPA proposes to approve the
monitoring strategy and other state implementation plan elements of
Oklahoma's 2022 SIP submission as meeting the requirements of 40 CFR
51.308(f)(6).
G. Requirements for Periodic Reports Describing Progress Towards the
Reasonable Progress Goals
Section 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,
40 CFR 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.
In its 2022 SIP submission, Oklahoma included the elements of the
periodic progress report specified in 40 CFR 51.308(f)(5) and 40 CFR
51.308(g)(1)-(5). Oklahoma's 2022 SIP submission describes the status
of measures of the long-term strategy from the first implementation
period as well as a summary of the emission reductions achieved through
implementation of those measures to address the requirements found in
40 CFR 51.308(g)(1) and (2). The status of control measure
implementation for the first planning period can be found in section
5.2: Status of control measure implementation and section 5.3: BART-
subject Units of Oklahoma's 2022 SIP submission, with the status of
each facility listed in section 5.3. Section 5.3.7: Summary of Planning
Period 1 Emission Reductions, table 5-8: SO2 Emission reductions
achieved from Planning Period 1 control measures, and 5-9: NOX Emission
reductions achieved from Planning Period 1 control measures in
Oklahoma's 2022 SIP submission contain a summary of the emission
reductions from implementation of control measures as of the end of the
first implementation period.
Section 51.308(g)(3) requires that for each Class I area within the
State, the State must assess the following visibility conditions and
changes, with values for most impaired, least impaired and/or clearest
days as applicable expressed in terms of five-year averages of these
annual values. Oklahoma's 2022 SIP submission includes a summary of
visibility conditions for Wichita Mountains in section 5.4: Visibility
conditions and progress, with a full analysis of visibility conditions
available in section 3: Visibility Monitoring.
Pursuant to 40 CFR 51.308(g)(4), Oklahoma evaluated emission trends
for reasonable progress and presented that information in section 5.5:
Changes in impairment contribution and Figure 5-1: Changes in SO2 and
NOX emissions from 2002-2017 in its 2022 SIP submission. Oklahoma
addresses 40 CFR 51.308(g)(5), in section 5.6: Significant changes in
anthropogenic emissions impeding progress in its 2022 SIP submission.
Oklahoma states in its 2022 SIP submission that emissions of all major
contributors to visibility impairment at Wichita Mountains have
decreased and notes that the reductions in anthropogenic emissions,
especially for SO<INF>2</INF>, were greater than anticipated.
Because Oklahoma's 2022 SIP submission addresses the requirements
of 40 CFR 51.308(g)(1) through (5), the EPA proposes to find that
Oklahoma has met the progress report requirements of 40 CFR
51.308(f)(5).
H. Requirements for State and 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)'s 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.
In section 8 of Oklahoma's 2022 SIP submission, Oklahoma described
how it met FLM consultation requirements and provided a list of all the
communications that were part of Oklahoma's state and FLM consultation
process. As stated earlier in this notice, Oklahoma is a member of
CenSARA. CenSARA hosted monthly conference calls with representatives
of member states, FLMs, and other organizations from 2019 through 2022.
Oklahoma participated in this process as part of ongoing consultation
between states and federal partners, including FLMs, including
consultation prior to the public hearing for Oklahoma's 2022 SIP
submission on July 1, 2022. In addition to the CenSARA conference
calls, ODEQ invited FLMs from the Fish and Wildlife Service (FWS),
National Park Service (NPS), and U.S. Department of Agriculture Forest
Service (FS) to
[[Page 6602]]
participate in conference calls specifically for outlining Oklahoma's
planning and progress to address its regional haze requirements.\86\
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\86\ See Oklahoma's 2022 SIP submission, section 8: Consultation
process during SIP development and appendix A: Consultation Process
and Documentation.
---------------------------------------------------------------------------
On September 30, 2021, Oklahoma sent draft copies of the Oklahoma
Regional Haze 2nd Planning Period SIP to FWS, NPS, and FS for the start
of the official consultation period required by 40 CFR 51.308(i)(2),
with comments requested by November 30, 2021. In addition, a virtual
meeting was held between Oklahoma and the FLMs on November 22, 2021, to
discuss the FLMs' comments on the draft SIP. Oklahoma received comments
from one FLM, FS, on the draft SIP, and in its response, Oklahoma made
changes where appropriate that were incorporated into the final SIP.
Both the FLM comments and Oklahoma response were included as part of
the official submittal.\87\
---------------------------------------------------------------------------
\87\ See Oklahoma's 2022 SIP submission, section 8 and appendix
H: Federal Land Manager Comments and Responses.
---------------------------------------------------------------------------
In its comments, FS was generally supportive of Oklahoma's approach
on its consideration of NO<INF>X</INF> and SO<INF>2</INF> sources, the
selection threshold, and the assessment of the facilities' modeled
impact on FS Class I areas. However, FS had concerns about the four-
factor analysis for Hugo Generating Station and the implicit cost-
effectiveness threshold used by Oklahoma for the second planning
period, stating that using the same threshold used in the first
planning period was inappropriate and a higher threshold should be
utilized. FS additionally requested a more detailed assessment of the
facility based on different factors that they felt could increase the
feasibility of control adoption. FS also requested assurance that
Oklahoma would continue to recognize the ecological role of prescribed
fires and adjust the glidepath for the inclusion of those emissions
accordingly. In its response, Oklahoma stated that they disagreed that
new sources identified in the second planning period should
automatically have a higher cost-effectiveness threshold. In response
to FS's comments, Oklahoma coordinated with the Hugo Generating Station
to provide additional assessments of the factors that FS suggested.
Oklahoma found that its original assessment of the Hugo Generating
Station in the draft SIP remained a reasonable conclusion but updated
the SIP to reflect the additional evaluation conducted. Oklahoma
additionally added language that FS requested on the use of prescribed
fires into the SIP.\88\
---------------------------------------------------------------------------
\88\ Id.
---------------------------------------------------------------------------
Oklahoma held the public comment period for its draft Oklahoma
Regional Haze 2nd Planning Period SIP from June 1, 2022, through July
1, 2022, and held a public hearing for the SIP on July 1, 2022.
Oklahoma published notice of the SIP proposal and details of the public
hearing on its website and sent notifications to those that requested
public notice opportunities. The published notice also contained a
summary of the conclusions and recommendations of the FLMs and how
Oklahoma addressed them. No additional comments were received by the
FLMs during Oklahoma's public comment period. EPA proposes to find that
the requirements of CAA section 169A(d) were met, as EPA determined
that opportunity for FLM consultation was provided at least 60 days
before the public notice or hearing date, with the public notice
containing the FLM's conclusions and recommendations during the
consultation process.\89\
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\89\ See Oklahoma's 2022 SIP submission, section 8 and appendix
L: Public Notice and Hearing Documentation.
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To address 40 CFR 51.308(i)(4) requirements, Oklahoma provided
assurance in the SIP that it would keep the FLMs aware of future
updates to its regional haze SIP and progress reports through direct
correspondence and through CenSARA.
Compliance with 40 CFR 51.308(i) is dependent on compliance with 40
CFR 51.308(f)(2)'s long-term strategy provisions and 40 CFR
51.308(f)(3)'s reasonable progress goals provisions. Because the EPA is
proposing to approve Oklahoma's long-term strategy under section
51.308(f)(2) and the reasonable progress goals under section
51.308(f)(3), and based on its assessment of the Oklahoma's 2022 SIP
submission provided in this section, the EPA proposes to find that
Oklahoma has satisfied the requirements under 40 CFR 51.308(i) to
consult with the FLMs on its regional haze SIP for the second
implementation period.
V. Proposed Action
The EPA is proposing approval of Oklahoma's 2022 SIP submission
addressing the requirements of the second implementation period of the
RHR. Specifically, the EPA is proposing approval of Oklahoma's 2022 SIP
submission relating to:
(1) 40 CFR 51.308(f)(1): calculations of baseline, current, and
natural visibility conditions, progress to date, and the uniform rate
of progress (URP);
(2) 40 CFR 51.308(f)(2): long-term strategy;
(3) 40 CFR 51.308(f)(3): reasonable progress goals (RPGs);
(4) 40 CFR 51.308(f)(4): reasonably attributable visibility
impairment (RAVI);
(5) 40 CFR 51.308(f)(5) and 40 CFR 51.308(g): progress report
requirements;
(6) 40 CFR 51.308(f)(6): monitoring strategy and other
implementation plan requirements; and
(7) 40 CFR 51.308(i): FLM consultation.
The EPA is proposing to approve as part of Oklahoma's 2022 SIP
submission source-specific requirements for (1) the ONEOK Maysville Gas
Plant as described in the accompanying Regional Haze Agreement between
ONEOK and ODEQ, Case No. 22-085, dated May 6, 2022, and (2) the Mustang
Gas Binger Plant as described in the accompanying Regional Haze
Agreement between Mustang Gas and ODEQ, Case No. 26-008, dated January
16, 2026. The ONEOK Regional Haze Agreement is the enforceable
mechanism for retiring ONEOK Maysville Gas Plant's remaining six older,
inefficient natural gas-fueled engines by December 31, 2028. The
Mustang Gas Regional Haze Agreement is the enforceable mechanism for
the operation of NO<INF>X</INF> controls on its remaining natural gas
engine within one year after EPA approval of Oklahoma's 2022 SIP
submission. The EPA is proposing to approve all requirements set forth
in the ONEOK Regional Haze Agreement and Mustang Gas Regional Haze
Agreement as source-specific revisions to be incorporated into the
Oklahoma SIP.
VI. Incorporation by Reference
In this action, we are proposing to include in a final rule
regulatory text that includes incorporation by reference. In accordance
with the requirements of 1 CFR 51.5, we are proposing to incorporate by
reference revisions to the Oklahoma source-specific requirements as
described in section V of this preamble, Proposed Action. We have made,
and will continue to make, these documents generally available
electronically through <a href="http://www.regulations.gov">www.regulations.gov</a> (please contact the person
identified in the FOR FURTHER INFORMATION CONTACT section of this
preamble for more information).
VII. Impact on Areas of Indian Country
Following the U.S. Supreme Court decision in McGirt v. Oklahoma,
140 S. Ct. 2452 (2020), the Governor of the State of Oklahoma requested
approval under section 10211(a) of the Safe, Accountable, Flexible,
Efficient
[[Page 6603]]
Transportation Equity Act of 2005: A Legacy for Users, Public Law 109-
59, 119 Stat. 1144, 1937 (August 10, 2005) (``SAFETEA''), to administer
in certain areas of Indian country (as defined at 18 U.S.C. 1151) the
State's environmental regulatory programs that were previously approved
by the EPA outside of Indian country. The State's request excluded
certain areas of Indian country further described below. In addition,
the State only sought approval to the extent that such approval was
necessary for the State to administer a program in light of Oklahoma
Dept. of Environmental Quality v. EPA, 740 F.3d 185 (D.C. Cir.
2014).\90\
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\90\ In ODEQ v. EPA, the D.C. Circuit held that under the CAA,
states have the authority to implement a SIP in non-reservation
areas of Indian country in the state, unless there has been a
demonstration of tribal jurisdiction. Under the D.C. Circuit's
decision, the CAA does not provide authority to states to implement
SIPs in Indian reservations.
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The EPA has approved Oklahoma's SAFETEA request to administer all
of the State's EPA-approved environmental regulatory programs in the
requested areas of Indian country. As requested by Oklahoma, EPA's
approval under SAFETEA does not include Indian country lands, including
rights-of-way running through the same, that: (1) qualify as Indian
allotments, the Indian titles to which have not been extinguished,
under 18 U.S.C. 1151(c); (2) are held in trust by the United States on
behalf of an individual Indian or Tribe; or (3) are owned in fee by a
Tribe, if the Tribe (a) acquired that fee title to such land, or an
area that included such land, in accordance with a treaty with the
United States to which such Tribe was a party, and (b) never allotted
the land to a member or citizen of the Tribe (collectively ``excluded
Indian country lands'').
The EPA's approval under SAFETEA expressly provided that to the
extent the EPA's prior approvals of Oklahoma's environmental programs
excluded Indian country, any such exclusions are superseded for the
geographic areas of Indian country covered by the EPA's approval of
Oklahoma's SAFETEA request.\91\ The approval also provided that future
revisions or amendments to Oklahoma's approved environmental regulatory
programs would extend to the covered areas of Indian country (without
any further need for additional requests under SAFETEA).
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\91\ The EPA's prior approvals relating to Oklahoma's SIP
frequently noted that the SIP was not approved to apply in areas of
Indian country (except as explained in the D.C. Circuit's decision
in ODEQ v. EPA) located in the State. See, e.g., 84 FR 30918, June
28, 2019. Such prior expressed limitations are superseded by the
EPA's approval of Oklahoma's SAFETEA request.
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As explained above, the EPA is proposing to approve the 2022
Oklahoma Regional Haze SIP for meeting requirements under 40 CFR
51.308(f)(1) through (6), (g), and (i) and which will apply statewide.
Consistent with the D.C. Circuit's decision in ODEQ v. EPA and with the
EPA's SAFETEA approval, these SIP revisions will apply to areas of
Indian country as follows: (1) pursuant to the SAFETEA approval, the
SIP revisions will apply to all Indian country in the State of Oklahoma
other than the excluded Indian country lands as described above; and
(2) pursuant to the D.C. Circuit's decision in ODEQ v. EPA, the SIP
revisions will also apply to any Indian allotments or dependent Indian
communities that are located outside of any Indian reservation and over
which there has been no demonstration of tribal authority.
VIII. Statutory and Executive Order Reviews
Under the CAA, the Administrator is required to approve a SIP
submission that complies with the provisions of the CAA and applicable
Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in
reviewing SIP submissions, 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 proposed action:
<bullet> Is not a ``significant regulatory action'' subject to
review by the Office of Management and Budget under Executive Order
12866 (58 FR 51735, October 4, 1993);
<bullet> Is not subject to Executive Order 14192 (90 FR 9065,
February 6, 2025) because State Implementation Plan approvals under the
CAA are exempt from review under Executive Order 12866;
<bullet> Does not impose an information collection burden under the
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
<bullet> 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.);
<bullet> 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);
<bullet> Does not have Federalism implications as specified in
Executive Order 13132 (64 FR 43255, August 10, 1999);
<bullet> Is not an economically significant regulatory action based
on health or safety risks subject to Executive Order 13045 (62 FR
19885, April 23, 1997);
<bullet> Is not a significant regulatory action subject to
Executive Order 13211 (66 FR 28355, May 22, 2001);
<bullet> 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
This proposed approval of the 2022 Oklahoma Regional Haze SIP that
addressed the requirements of 40 CFR 51.308(f)(1) through (6), (g), and
(i), and will apply, if finalized as proposed, to certain areas of
Indian country throughout Oklahoma as discussed in the preamble, and
therefore has Tribal implications as specified in E.O. 13175 (65 FR
67249, November 9, 2000). However, this action will neither impose
substantial direct compliance costs on federally recognized Tribal
governments, nor preempt tribal law. This action will not impose
substantial direct compliance costs on federally recognized Tribal
governments because no actions will be required of Tribal governments.
This action will also not preempt Tribal law as no Oklahoma tribe
implements a regulatory program under the CAA, and thus does not have
applicable or related Tribal laws. Consistent with the EPA Policy on
Consultation with Indian Tribes (December 7, 2023), the EPA has offered
consultation to Tribal governments that may be affected by this action
and provided information about this action.
List of Subjects in 40 CFR Part 52
Environmental protection, Air pollution control, Incorporation by
reference, Intergovernmental relations, Nitrogen dioxide, Ozone,
Particulate matter, Reporting and recordkeeping requirements, Sulfur
oxides.
Authority: 42 U.S.C. 7401 et seq.
Dated: February 3, 2026.
Walter Mason,
Regional Administrator, Region 6.
[FR Doc. 2026-02843 Filed 2-11-26; 8:45 am]
BILLING CODE 6560-50-P
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</html>Indexed from Federal Register on February 12, 2026.
This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.