Rule2025-20407
Air Plan Approval; California; Eastern Kern Air Pollution Control District; Stationary Combustion Turbines
Primary source
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Published
November 20, 2025
Effective
December 22, 2025
Issuing agencies
Environmental Protection Agency
Abstract
The Environmental Protection Agency (EPA) is taking final action to approve a revision to the Eastern Kern Air Pollution Control District (EKAPCD or "District") portion of the California State Implementation Plan (SIP). This revision concerns emissions of oxides of nitrogen (NO<INF>X</INF>) from stationary gas turbines. We are approving a local rule that regulates these emissions sources under the Clean Air Act (CAA or "Act").
Full Text
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<title>Federal Register, Volume 90 Issue 222 (Thursday, November 20, 2025)</title>
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[Federal Register Volume 90, Number 222 (Thursday, November 20, 2025)]
[Rules and Regulations]
[Pages 52242-52245]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-20407]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52
[EPA-R09-OAR-2025-0060; FRL-12608-03-R9]
Air Plan Approval; California; Eastern Kern Air Pollution Control
District; Stationary Combustion Turbines
AGENCY: Environmental Protection Agency (EPA).
ACTION: Final rule.
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SUMMARY: The Environmental Protection Agency (EPA) is taking final
action to approve a revision to the Eastern Kern Air Pollution Control
District (EKAPCD or ``District'') portion of the California State
Implementation Plan (SIP). This revision concerns emissions of oxides
of nitrogen (NO<INF>X</INF>) from stationary gas turbines. We are
approving a local rule that regulates these emissions sources under the
Clean Air Act (CAA or ``Act'').
DATES: This rule is effective December 22, 2025.
ADDRESSES: The EPA has established a docket for this action under
Docket ID
[[Page 52243]]
No. EPA-R09-OAR-2025-0060. All documents in the docket are listed on
the <a href="https://www.regulations.gov">https://www.regulations.gov</a> website. Although listed in the index,
some information is not publicly available, e.g., Confidential Business
Information (CBI) or other information whose disclosure is restricted
by statute. Certain other material, such as copyrighted material, is
not placed on the internet and will be publicly available only in hard
copy form. Publicly available docket materials are available through
<a href="https://www.regulations.gov">https://www.regulations.gov</a>, or please contact the person identified in
the FOR FURTHER INFORMATION CONTACT section for additional availability
information. If you need assistance in a language other than English or
if you are a person with a disability who needs a reasonable
accommodation at no cost to you, please contact the person identified
in the FOR FURTHER INFORMATION CONTACT section.
FOR FURTHER INFORMATION CONTACT: La Kenya Evans-Hopper, EPA Region IX,
75 Hawthorne St., San Francisco, CA 94105; phone: (415) 972-3245;
email: <a href="/cdn-cgi/l/email-protection#026774636c716a6d727267702c6e6369676c7b63426772632c656d74"><span class="__cf_email__" data-cfemail="9ffae9fef1ecf7f0efeffaedb1f3fef4faf1e6fedffaeffeb1f8f0e9">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION: Throughout this document, ``we,'' ``us,''
and ``our'' refer to the EPA.
Table of Contents
I. Proposed Action
II. Public Comments and EPA Responses
III. EPA Action
IV. Incorporation by Reference
V. Statutory and Executive Order Reviews
I. Proposed Action
On June 20, 2025 (90 FR 26232), the EPA proposed to approve the
following rule into the California SIP.
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Local agency Rule No. Rule title Amended Submitted
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EKAPCD............................... 425 Stationary Gas Turbines 11/13/2024 12/12/2024
(Oxides of Nitrogen).
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We proposed to approve this rule because we determined that it
complies with the relevant CAA requirements. Our proposed action
contains more information on the rule and our evaluation.
II. Public Comments and EPA Responses
The EPA's proposed action provided a 30-day public comment period.
During this period, we received four anonymous comments. The full texts
of these comments are available in the docket for this rulemaking. Two
of the comments were positive in response to our Determination to Defer
Sanctions.\1\ One comment was in support of our decision to defer
offset and highway sanctions for California and encouraged the EPA to
maintain oversight for the implementation of EKAPCD Rule 425--
Stationary Gas Turbines (Oxides of Nitrogen), amended November 13, 2024
(``Rule 425''). The commenter stated that long-term compliance and
transparency will be key to protecting public health in the Eastern
Kern region. The second comment was in support of approving Rule 425
into the SIP. The EPA thanks the commenters for their comments. As
discussed in more detail below, we received two additional comments
addressing specific aspects of the proposed rulemaking.
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\1\ ``Determination to Defer Sanctions; California; Eastern Kern
Air Pollution Control District; Stationary Combustion Turbines,''
June 20, 2025 (90 FR 26207).
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The first of these two additional comments recommended that the EPA
not revise the air pollution requirements in Eastern Kern and use ``the
stricter CA regulations'' for every State in the Union. The EPA thanks
the commenter for their comment. This rulemaking is for a specific
local air pollution control district within California, the EKAPCD, and
air pollution control requirements outside of the EKAPCD are beyond the
scope of this rule. With respect to the recommendation that the EPA not
revise the air pollution requirements within EKAPCD, and instead use
``stricter CA regulations'' in EKAPCD, such an approach is not
available in the current rulemaking. Firstly, the commenter has not
identified any specific California regulations believed to be
``stricter'' than Rule 425. Rule 425 regulates emissions of oxides of
nitrogen (NO<INF>X</INF>) from combustion turbines. In California,
local air pollution control districts typically adopt regulations for
these types of emissions sources and submit them to the California Air
Resources Board (CARB). CARB then decides whether to submit these rules
to the EPA for inclusion in the SIP. It is the California State
Government, through CARB, that maintains the California SIP and chooses
which regulations and materials to submit to the EPA for including into
the SIP. Rule 425 is thus the applicable California regulation for the
area. Accordingly, it is not clear what other ``stricter CA
regulation'' the commenter is referring to. There is no other
applicable California regulation that has been submitted to the EPA.
Although CARB may directly regulate some categories of sources, we are
not aware of any CARB regulations that establish NO<INF>X</INF>
emissions limitations for combustion turbines. Secondly, under the
cooperative federalism framework established by the Act, the states
adopt regulations and submit them to the EPA for approval into the SIP.
Under section 110(k)(3) of the CAA, the EPA must approve a SIP
submission if it meets the applicable requirements of the Act.
Accordingly, unless the EPA has identified a deficiency with the
present submission, the EPA does not have discretion to disapprove the
submission. In addition, CAA section 110(c)(1)(B) specifies that the
EPA may only impose its own regulations, using a Federal Implementation
Plan (FIP), if the EPA has disapproved a SIP submission and identified
a deficiency in that submission that prevents full approval. The EPA
may not otherwise substitute its own regulations for those submitted by
the state.
To the extent that the commenter may be suggesting that the EPA
disapprove the submission because Rule 425 should be ``stricter'' to
meet CAA requirements, the commenter has not specified a deficiency
that would permit the EPA to disapprove the submission, and we disagree
with this suggestion. Our proposed action and technical support
document (TSD) contained an analysis of the rule, including its
stringency, concluding that it meets the applicable requirements of the
Act. As explained in our proposal, the EKAPCD is required to implement
Reasonably Available Control Technology (RACT) requirements for any
category of sources covered by a Control Techniques Guidelines document
and for any major stationary source of volatile organic compounds
(VOCs) or NO<INF>X</INF>. See CAA sections 182(b)(2) and (f). The
District relies on Rule 425 to establish RACT-level controls for
combustion turbines at major sources of NO<INF>X</INF> within the
District.
In this action, California is correcting a deficiency that we
previously identified related to the stringency of the NO<INF>X</INF>
emissions limitations in Rule 425 for a single combustion turbine in
the District, the Westinghouse W251B10 combustion turbine.\2\ In 2023,
we
[[Page 52244]]
determined that Rule 425 was largely consistent with the relevant CAA
requirements, including the requirement to implement RACT for covered
major sources, except for the Westinghouse W251B10 combustion turbine.
To address the deficiency, the District amended Rule 425 by lowering
the NO<INF>X</INF> emissions limitation applicable to the unit when
burning gaseous fuel from 25 parts per million by volume (ppmv) to 20
ppmv and removed the liquid fuel emissions limitation of 65 ppmv. With
respect to the RACT requirement, the Westinghouse W251B10 combustion
turbine is currently equipped with dry low NO<INF>X</INF> combustors to
control NO<INF>X</INF> emissions. The EKAPCD provided a response
document with an analysis to demonstrate that it is not cost effective
for this Westinghouse turbine to be retrofitted with selective
catalytic reduction (SCR), and that SCR is thus not required to meet
RACT for this unit.\3\ The EPA concluded that Rule 425 represents RACT
level control for this unit and that the District has addressed the
prior deficiency. Please see our proposal and TSD for additional
details.
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\2\ 88 FR 39182 (June 15, 2025).
\3\ Response to Eastern Kern Air Pollution Control District
Request regarding the SIP and Rule 425 Modification, sent on January
3, 2024 (Response Document) as found in our docket at EPA-R09-OAR-
2025-0060.
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Nothing in the submitted comment has changed our assessment or
suggested that new information should call this conclusion into
question. Accordingly, the EPA concludes that the previous deficiency
has been addressed, and Rule 425 meets all applicable CAA requirements
regarding enforceability, RACT, and SIP revisions. Therefore, the EPA
is finalizing approval of the SIP submission.
The second comment that we received addressing an aspect of the
proposed rulemaking stated that ``[t]he proposed EPA reporting should
be included in the matter, as informative data relevant for disclosure
purposes and to provide conclusive details on the history of the
potentially harmful impact to the citizens in the region.'' The EPA
thanks the commenter for their comment. To clarify, the EPA did not
propose any additional requirements beyond those found in Rule 425. As
mentioned in our proposal, the revised rule includes updates to the
reporting requirements section of the rule. These reports are submitted
to the District. Thus, the EPA understands this comment as being
supportive of our proposed approval of Rule 425 that would include
approving these revised reporting requirements into the SIP.
III. EPA Action
No comments were submitted that change our assessment of the rule
as described in our proposed action. Therefore, as authorized in
section 110(k)(3) of the Act, the EPA is approving this rule into the
California SIP. The November 13, 2024 version of Rule 425 will replace
the previously approved version of this rule in the SIP. This approval
resolves all deficiencies forming the basis for our previous limited
disapproval in 2023 of the prior version of Rule 425. This action also
permanently terminates all sanctions clocks and FIP clocks triggered by
our June 15, 2023 limited disapproval action.
IV. Incorporation by Reference
In this rule, the EPA is finalizing regulatory text that includes
incorporation by reference. In accordance with requirements of 1 CFR
51.5, the EPA is finalizing the incorporation by reference of Eastern
Kern Air Pollution Control District, Rule 425, Stationary Gas Turbines
(Oxides of Nitrogen), amended on November 13, 2024, which regulates
NO<INF>X</INF> emissions from stationary gas turbines. Therefore, these
materials have been approved by the EPA for inclusion in the SIP, have
been incorporated by reference by the EPA into that plan, are fully
federally enforceable under sections 110 and 113 of the CAA as of the
effective date of the final rulemaking of the EPA's approval, and will
be incorporated by reference in the next update to the SIP
compilation.\4\ The EPA has made, and will continue to make, these
documents available through <a href="https://www.regulations.gov">https://www.regulations.gov</a> and at the EPA
Region IX Office (please contact the person identified in the FOR
FURTHER INFORMATION CONTACT section of this preamble for more
information).
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\4\ 62 FR 27968 (May 22, 1997).
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V. Statutory and Executive Order Reviews
Under the CAA, the Administrator is required to approve a SIP
submission that complies with the provisions of the Act and applicable
Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in
reviewing SIP submissions, the EPA's role is to approve state choices,
provided that they meet the criteria of the CAA. Accordingly, this
action merely approves state law as meeting Federal requirements and
does not impose additional requirements beyond those imposed by state
law. For that reason, this 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 SIP actions 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 subject to Executive Order 13045 (62 FR 19885,
April 23, 1997) because it approves a state program;
<bullet> Is not a significant regulatory action subject to
Executive Order 13211 (66 FR 28355, May 22, 2001); and
<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.
In addition, the SIP is not approved to apply on any Indian
reservation land or in any other area where the EPA or an Indian Tribe
has demonstrated that a Tribe has jurisdiction. In those areas of
Indian country, the rule does not have Tribal implications and will not
impose substantial direct costs on Tribal governments or preempt Tribal
law as specified by Executive Order 13175 (65 FR 67249, November 9,
2000).
This action is subject to the Congressional Review Act, and the EPA
will submit a rule report to each House of the Congress and to the
Comptroller General of the United States. This action is not a ``major
rule'' as defined by 5 U.S.C. 804(2).
Under section 307(b)(1) of the CAA, petitions for judicial review
of this action must be filed in the United States Court of Appeals for
the appropriate circuit by January 20, 2026. Filing a petition for
reconsideration by the Administrator of this final rule does not affect
the finality of this action for the purposes of judicial review nor
does it extend the time within which a petition for judicial review may
be filed, and shall not postpone the effectiveness of such rule or
action. This action may not be challenged later in proceedings to
[[Page 52245]]
enforce its requirements. (See section 307(b)(2).)
List of Subjects in 40 CFR Part 52
Environmental protection, Air pollution control, Incorporation by
reference, Intergovernmental relations, Nitrogen oxides, Ozone,
Reporting and recordkeeping requirements.
Dated: November 10, 2025.
Michael Martucci,
Acting Regional Administrator, Region IX.
For the reasons stated in the preamble, the Environmental
Protection Agency amends part 52, chapter I, title 40 of the Code of
Federal Regulations as follows:
PART 52--APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS
0
1. The authority citation for part 52 continues to read as follows:
Authority: 42 U.S.C. 7401 et seq.
Subpart F--California
0
2. Amend Sec. 52.220a, paragraph (c), under the subheading ``Table 10-
EPA-Approved Eastern Kern Air Pollution Control District Regulations;
Kern County air Pollution Control District Regulations,'' by revising
the entry for ``425'', to read as follows:
Sec. 52.220a Identification of plan--in part.
* * * * *
(c) * * *
Table 10--EPA-Approved Eastern Kern Air Pollution Control District Regulations; Kern County Air Pollution
Control District Regulations
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Additional
District citation Title/subject State effective date EPA approval date explanation
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* * * * * * *
425..................... Stationary Gas November 13, 2024... 11/20/2025, 90 FR Submitted on
Turbines (Oxides of [INSERT FEDERAL December 12, 2024.
Nitrogen). REGISTER PAGE WHERE
THE DOCUMENT
BEGINS].
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[FR Doc. 2025-20407 Filed 11-19-25; 8:45 am]
BILLING CODE 6560-50-P
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