# Identification of plan.
**AGENCY:**
Environmental Protection Agency (EPA).
**ACTION:**
Direct final rule.
**SUMMARY:**
The Environmental Protection Agency (EPA) is taking direct final action to approve revisions to the Wyoming State Implementation Plan (SIP) submitted by the Wyoming Department of Environmental Quality (WDEQ) on December 16, 2024. WDEQ requested the EPA approve the revised rules for Chapters 2, 3, 4, 8, and 14 in the Wyoming Air Quality Standards and Regulations (WAQSR). The revised rules include non-substantive updates to rule language that ensure consistent grammar, formatting, and written clarity as well as updated references to the Code of Federal Regulations (CFR). The EPA is taking this action pursuant to the Clean Air Act (CAA).
**DATES:**
This direct final rule is effective on November 10, 2025, without further notice, unless the EPA receives adverse comments by October 14, 2025. If adverse comments are received, the EPA will publish a timely withdrawal of the direct final rule in the *Federal Register* informing the public that the rule will not take effect.
**ADDRESSES:**
Submit your comments, identified by Docket ID No. EPA-R08-OAR-2025-0204, to the Federal Rulemaking Portal: *https://www.regulations.gov.* Follow the online instructions for submitting comments. Once submitted, comments cannot be edited or removed from *https://www.regulations.gov.* The EPA may publish any comment received to its public docket. Do not submit electronically any information you consider to be Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Multimedia submissions (audio, video, etc.) must be accompanied by a written comment. The written comment is considered the official comment and should include discussion of all points you wish to make. The EPA will generally not consider comments or comment contents located outside of the primary submission ( *i.e.,* on the web, cloud, or other file sharing system). For additional submission methods, the full EPA public comment policy, information about CBI or multimedia submissions, and general guidance on making effective comments, please visit *https://www.epa.gov/dockets/commenting-epa-dockets.*
*Docket:* The EPA has established a docket for this action under Docket ID No. EPA-R08-OAR-2025-0204. All documents in the docket are listed on the *https://www.regulations.gov* website. Although listed in the index, some information is not publicly available, *e.g.,* CBI or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material, is not placed on the internet and will be publicly available only in hard copy form. Publicly available docket materials are available through *https://www.regulations.gov,* or please contact the person identified in the *FOR FURTHER INFORMATION CONTACT* section for additional availability information.
**FOR FURTHER INFORMATION CONTACT:**
Chelsea Cancino, Air and Radiation Division, EPA, Region 8, Mailcode 8ARD-IO, 1595 Wynkoop Street, Denver, Colorado 80202-1129, telephone number: (303) 312-6276, email address: *[email protected].*
**SUPPLEMENTARY INFORMATION:**
Throughout this document “we,” “us,” and “our” means the EPA.
**I. Background**
WDEQ reviewed its regulations and concluded that rule revisions were needed to modify the wording of selected text to correct typographical errors and reflect new formatting guidelines. WDEQ adopted these various minor revisions and updated their rules on April 30, 2024, and then requested that the EPA approve these revisions into the Wyoming SIP in a submittal dated December 16, 2024.
**II. The EPA's Evaluation**
WDEQ has requested that the EPA approve revised rules under Chapter 2, 3, 4, 8, and 14 of the WAQSR. These revisions adopt minor changes in rule language to meet updated state style and formatting guidelines. These revisions also include Incorporation by Reference (IBR) material in Wyoming's SIP. IBR allows state agencies to comply with the requirement to adopt certain Federal rules by referring to materials already published in the CFR. In this SIP revision, Wyoming is incorporating by reference 40 CFR parts 50, 51, 53, 60, 81, and 93 as published on July 1, 2023. No terms or definitions were added or removed from the revised sections. Since the revisions are minor in nature, do not make this rule less stringent, and do not affect the scope or intent of the rules, the EPA finds that the revisions to these chapters are approvable.
With regard to the approval of WAQSR Chapter 02, Section 04, “Ambient Standards for Sulfur Oxides,” we note that the December 16, 2024 submittal supersedes the revisions to this section contained in WDEQ's February 10, 2014 SIP submittal that the EPA had not previously acted on. [^1]
[^1] See 80 FR 45608, July 31, 2015, in which the EPA did not act on the State's proposed revisions to WAQSR Chapter 02, Section 04(a), 4(a)(i) and 4(a)(ii). These provisions are removed from Chapter 02, Section 04 as submitted December 16, 2024, and the EPA considers this submittal to supersede that of February 10, 2014.
**III. Final Action**
The EPA is approving the December 16, 2024, submission by WDEQ as a revision to the Wyoming SIP. Specifically, the EPA is approving updates to WAQSR Chapters 2, 3, 4, 8, and 14 as detailed in table 1 below.
We are publishing this action without a prior proposed rule because we view these SIP revisions as noncontroversial and anticipate no relevant adverse comment. The revisions are administrative in nature and do not constitute substantive changes to Wyoming's SIP. However, in the “Proposed Rules” section of this *Federal Register* publication, we are publishing a separate action to approve the revisions to Wyoming's SIP submitted by the WDEQ on December 16, 2024 if adverse comments are received on this direct final rule. We will not institute a second comment period on this action. Any parties interested in commenting must do so at this time. For further information about commenting on this rule, see the *ADDRESSES* section of this document.
If the EPA receives adverse comment, we will publish a timely withdrawal in the *Federal Register* informing the public that this direct final rule, or the relevant provisions of this rule, will not take effect. We would address all public comments in any subsequent final rule based on the proposed rule. If we receive adverse comment on a distinct provision of this rulemaking, we will publish a timely withdrawal in the *Federal Register* indicating which provisions we are withdrawing. The provisions that are not withdrawn will become effective on the date set out above, notwithstanding adverse comment on any other provision.
| Rule No. | Rule title | Revision summary | EPA's proposed |
| --- | --- | --- | --- |
| | | | |
| Section 02 | Ambient Standards for Particulate Matter | Non-substantive formatting revisions | Approval. |
| Section 03 | Ambient Standards for Nitrogen Oxides | Non-substantive formatting revisions | Approval. |
| Section 04 | Ambient Standards for Sulfur Oxides | Non-substantive formatting revisions | Approval. |
| Section 05 | Ambient Standards for Carbon Monoxide | Non-substantive formatting revisions | Approval. |
| Section 06 | Ambient Standards for Ozone | Non-substantive formatting revisions | Approval. |
| Section 08 | Ambient Standards for Suspended Sulfates | Non-substantive formatting revisions | Approval. |
| Section 10 | Ambient Standards for Lead | Non-substantive formatting revisions | Approval. |
| Section 12 | Incorporation by Reference | Updated adoption of the CFR as of July 1, 2023 and associated weblink | Approval. |
| | | | |
| Section 02 | Emission Standards for Particulate Matter | Non-substantive formatting revisions | Approval. |
| Section 03 | Emission Standards for Nitrogen Oxides | Non-substantive formatting revisions | Approval. |
| Section 04 | Emission Standards for Sulfur Oxides | Non-substantive formatting revisions | Approval. |
| Section 05 | Emission Standards for Carbon Monoxide | Non-substantive formatting revisions | Approval. |
| Section 06 | Emission Standards for Volatile Organic Compounds | Non-substantive formatting revisions | Approval. |
| Section 09 | Incorporation by Reference | Updated adoption of the CFR as of July 1, 2023 and associated weblink | Approval. |
| | | | |
| Section 02 | Existing Sulfuric Acid Production Units | Non-substantive formatting revisions | Approval. |
| Section 03 | Existing Nitric Acid Manufacturing Plants | Non-substantive formatting revisions | Approval. |
| | | | |
| Section 02 | Sweetwater County Particulate Matter Regulations | Non-substantive formatting revisions | Approval. |
| Section 03 | Conformity of General Federal Actions to State Implementation Plans | Non-substantive formatting revisions | Approval. |
| Section 05 | Ozone Nonattainment Emission Inventory Rule | Non-substantive formatting revisions | Approval. |
| Section 10 | Incorporation by Reference | Updated adoption of the CFR as of July 1, 2023 and associated weblink | Approval. |
| | | | |
| Section 2 | Western Backstop Sulfur Dioxide Trading Program | Non-substantive formatting revisions | Approval. |
| Section 3 | Sulfur Dioxide Milestone Inventory | Non-substantive formatting revisions | Approval. |
| App A | WEB Chapter 14, Section 2 Monitoring Protocols | Non-substantive formatting revisions | Approval. |
**IV. Incorporation by Reference**
In this document, the EPA is finalizing regulatory text that includes IBR. In accordance with requirements of 1 CFR 51.5, the EPA is finalizing the IBR of WAQSR as described in section III. of this preamble and as set forth below in the amendments set forth to 40 CFR part 52. The EPA has made, and will continue to make, these materials generally available through *https://www.regulations.gov* and at the EPA Region 8 Office (please contact the person identified in the *FOR FURTHER INFORMATION CONTACT* section of this preamble for more information). Therefore, these materials have been approved by the EPA for inclusion in the SIP, have been IBR 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 IBR in the next update to the SIP compilation. [^2]
[^2] 62 FR 27968 (May 22, 1997).
**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 CAA 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:
• 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);
• Is not subject to Executive Order 14192 (90 FR 9065, February 6, 2025) because SIP actions are exempt from review under Executive Order 12866;
• Does not impose an information collection burden under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501 *et seq.* );
• Is certified as not having a significant economic impact on a substantial number of small entities under the Regulatory Flexibility Act (5 U.S.C. 601 *et seq.* );
• Does not contain any unfunded mandate or significantly or uniquely affect small governments, as described in the Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4);
• Does not have federalism implications as specified in Executive Order 13132 (64 FR 43255, August 10, 1999);
• Is not subject to Executive Order 13045 (62 FR 19885, April 23, 1997) because it approves a state program;
• Is not a significant regulatory action subject to Executive Order 13211 (66 FR 28355, May 22, 2001); and
• 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 (CRA), 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 November 10, 2025. 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 enforce its requirements (see section 307(b)(2)).
**List of Subjects in 40 CFR Part 52**
Environmental protection, Air pollution control, Carbon monoxide, Greenhouse gases, Incorporation by reference, Intergovernmental relations, Lead, Nitrogen dioxide, Ozone, Particulate matter, Reporting and recordkeeping requirements, Sulfur oxides, Volatile organic compounds.
Dated: August 29, 2025.
Cyrus M. Western,
Regional Administrator, Region 8.
For the reasons stated in the preamble, the Environmental Protection Agency is amending title 40 CFR part 52 as follows:
**PART 52—APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS**
**40 CFR Part 52**
1. The authority citation for part 52 continues to read as follows:
**Authority:**
42 U.S.C. 7401 *et seq.*
**Subpart ZZ—Wyoming**
**40 CFR Part 52**
2. In § 52.2620, the table in paragraph (c) is amended by:
a. Under the heading “Chapter 02. Ambien Standards”, revising the entries “Section 02”, “Section 03”, “Section 04”, “Section 05”, “Section 06”, “Section 08”, “Section 10”, “Section 12”;
b. Under the heading “Chapter 03. General Emission Standards”, revising the entries “Section 02”, “Section 03”, “Section 04”, “Section 05”, “Section 06”, “Section 09”;
c. Under the heading “Chapter 04. State Performance Standards for Specific Existing Sources”, revising the entries “Section 02”, Section 03”;
d. Under the heading “Chapter 08. Non-attainment Area Regulations”, revising the entries “Section 02”, “Section 03”, “Section 05”, “Section 10”; and
e. Under the heading “Chapter 14. Emission Trading Program Regulations”, revising the entries “Section 2”, “Section 3”, and “App A”.
The revisions read as follows:
§ 52.2620
(c) * * *
| Rule No. | Rule title | State | EPA | Final rule | Comments |
| --- | --- | --- | --- | --- | --- |
| | | | | | |
| * * * * * * * | | | | | |
| | | | | | |
| Section 02 | Ambient Standards for Particulate Matter | 4/30/2024 | 9/11/2025 | 90 FR [insert
page where the document begins], 9/11/2025 | |
| | | | | | |
| * * * * * * * | | | | | |
| Section 03 | Ambient Standards for Nitrogen Oxides | 4/30/2024 | 9/11/2025 | 90 FR [insert
page where the document begins], 9/11/2025 | |
| Section 04 | Ambient Standards for Sulfur Oxides | 4/30/2024 | 9/11/2025 | 90 FR [insert
page where the document begins], 9/11/2025 | |
| Section 05 | Ambient Standards for Carbon Monoxide | 4/30/2024 | 9/11/2025 | 90 FR [insert
page where the document begins], 9/11/2025 | |
| Section 06 | Ambient Standards for Ozone | 4/30/2024 | 9/11/2025 | 90 FR [insert
page where the document begins], 9/11/2025 | |
| Section 08 | Ambient Standards for Suspended Sulfates | 4/30/2024 | 9/11/2025 | 90 FR [insert
page where the document begins], 9/11/2025 | |
| Section 10 | Ambient Standards for Lead | 4/30/2024 | 9/11/2025 | 90 FR [insert
page where the document begins], 9/11/2025 | |
| Section 12 | Incorporation by Reference | 4/30/2024 | 9/11/2025 | 90 FR [insert
page where the document begins], 9/11/2025 | |
| | | | | | |
| Section 02 | Emission Standards for Particulate Matter | 4/30/2024 | 9/11/2025 | 90 FR [insert
page where the document begins], 9/11/2025 | |
| Section 03 | Emission Standards for Nitrogen Oxides | 4/30/2024 | 9/11/2025 | 90 FR [insert
page where the document begins], 9/11/2025 | |
| Section 04 | Emission Standards for Sulfur Oxides | 4/30/2024 | 9/11/2025 | 90 FR [insert
page where the document begins], 9/11/2025 | |
| Section 05 | Emission Standards for Carbon Monoxide | 4/30/2024 | 9/11/2025 | 90 FR [insert
page where the document begins], 9/11/2025 | |
| Section 06 | Emission Standards for Volatile Organic Compounds | 4/30/2024 | 9/11/2025 | 90 FR [insert
page where the document begins], 9/11/2025 | |
| Section 09 | Incorporation by Reference | 4/30/2024 | 9/11/2025 | 90 FR [insert
page where the document begins], 9/11/2025 | |
| | | | | | |
| Section 02 | Existing Sulfuric Acid Production Units | 4/30/2024 | 9/11/2025 | 90 FR [insert
page where the document begins], 9/11/2025 | |
| Section 03 | Existing Nitric Acid Manufacturing Plants | 4/30/2024 | 9/11/2025 | 90 FR [insert
page where the document begins], 9/11/2025 | |
| | | | | | |
| * * * * * * * | | | | | |
| | | | | | |
| Section 02 | Sweetwater County Particulate Matter Regulations | 4/30/2024 | 9/11/2025 | 90 FR [insert
page where the document begins], 9/11/2025 | |
| Section 03 | Conformity of General Federal Actions to State Implementation Plans | 4/30/2024 | 9/11/2025 | 90 FR [insert
page where the document begins], 9/11/2025 | |
| Section 05 | Ozone Nonattainment Emission Inventory Rule | 4/30/2024 | 9/11/2025 | 90 FR [insert
page where the document begins], 9/11/2025 | |
| Section 10 | Incorporation by Reference | 4/30/2024 | 9/11/2025 | 90 FR [insert
page where the document begins], 9/11/2025 | |
| | | | | | |
| * * * * * * * | | | | | |
| | | | | | |
| Section 2 | Western Backstop Sulfur Dioxide Trading Program | 4/30/2024 | 9/11/2025 | 90 FR [insert
page where the document begins], 9/11/2025 | 90 FR [insert
page where the document begins], 9/11/2025. |
| Section 3 | Sulfur Dioxide Milestone Inventory | 4/30/2024 | 9/11/2025 | 90 FR [insert
page where the document begins], 9/11/2025 | 90 FR [insert
page where the document begins], 9/11/2025. |
| App A | Web Chapter 14, Section 2 Monitoring Protocols | 4/30/2024 | 9/11/2025 | 90 FR [insert
page where the document begins], 9/11/2025 | 90 FR [insert
page where the document begins], 9/11/2025. |
| | | | | | |
| * * * * * * * | | | | | |