# Identification of plan-in part.
**AGENCY:**
Environmental Protection Agency (EPA).
**ACTION:**
Final rule.
**SUMMARY:**
The Environmental Protection Agency (EPA) is taking final action to approve a revision to the Mojave Desert Air Quality Management District (MDAQMD) portion of the California State Implementation Plan (SIP). This revision concerns emissions of volatile organic compounds (VOCs) and oxides of nitrogen (NO <sub>X</sub> ) from internal combustion engines. We are approving a local rule that regulates these emission sources under the Clean Air Act (CAA or the “Act”). The EPA is also making additional administrative updates to the MDAQMD portion of the California SIP by correcting text in the Code of Federal Regulations.
**DATES:**
This rule is effective September 29, 2025.
**ADDRESSES:**
The EPA has established a docket for this action under Docket ID No. EPA-R09-OAR-2023-0202. 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.,* 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 *https://www.regulations.gov,* 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; telephone number: (415) 972-3245; email address: *[email protected].*
**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 April 7, 2023 (88 FR 20788), the EPA proposed to approve the following rule into the California SIP.
| Local agency | Rule No. | Rule title | Amended | Submitted |
| --- | --- | --- | --- | --- |
| MDAQMD | 1160 | Internal Combustion Engines | 01/23/23 | 03/03/23 |
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 one anonymous comment and one comment from MDAQMD. The full text of these comments is available in the docket for this rulemaking. The anonymous comment was supportive of the rule as a tool to address air pollution, particularly NO <sub>X</sub> emissions, and human health. After reviewing this comment, the EPA has determined that the comment is supportive of our proposed action and does not raise issues that change our assessment of MDAQMD Rule 1160.
The comment from MDAQMD did not address the EPA's evaluation of the submitted rule, or whether the EPA should approve it into the SIP. The MDAQMD comment requests that the EPA remove the previous versions of Rule 1160, amended October 26, 1994 (61 FR 56470) and amended January 22, 2018 (86 FR 50643), and South Coast Air Quality Management District (SCAQMD) Rule 1110, adopted November 6, 1981 (47 FR 18822) from the MDAQMD portion of the SIP and replace these rules with the final approval of Rule 1160. Our proposed action stated that the previous version of Rule 1160 will be removed and replaced with the version of Rule 1160 adopted on January 23, 2023. Accordingly, the January 22, 2018 version of the rule will be removed from the SIP with this final action.
The EPA notes that the version of Rule 1160 that was amended on October 26, 1994, has already been removed from the SIP. In our September 10, 2021 (86 FR 50643) limited approval and limited disapproval, we added text at 40 CFR 52.220(c)(207)(i)(D)(5) specifying that this version of Rule 1160 has been removed with replacement. However, this provision contained an incorrect cross reference to 40 CFR 52.220(c)(518)(i)(A)(6) instead of 40 CFR 52.220(c)(518)(i)(A)(7). We are correcting this cross reference in this final rule.
The version of SCAQMD Rule 1110 that is in the MDAQMD portion of the SIP is a 1981 program to demonstrate the effectiveness of NO <sub>X</sub> reduction technologies for stationary internal combustion engines. Although the rule is structured differently from Rule 1160, it applies to the same general category of sources. Rule 1110 had a ten-year time horizon and thus does not establish any currently applicable requirement on sources in the MDAQMD. The rule originally applied in parts of what is now the SCAQMD, Antelope Valley Air Quality Management District (AVAQMD), and the eastern portion of Riverside County (Palo Verde) of the MDAQMD. It has since been removed from the SCAQMD and AVAQMD portions of the California SIP, with both actions explaining that the rule was a fixed-term demonstration program that was no longer in use and had no sources subject to it. [^1] Because SCAQMD Rule 1110 does not establish any currently applicable emission controls in the MDAQMD, removing it from the MDAQMD portion of the SIP is a purely administrative revision and would not weaken the SIP in any way or otherwise interfere with any requirements of the CAA. Accordingly, pursuant to the request of the MDAQMD in both the submitted staff report and comment, the EPA in this final action is removing the 1981 version of SCAQMD Rule 1110 from the Riverside County portion of the MDAQMD portion of the SIP as an administrative revision to the SIP.
[^1] 79 FR 40675, July 14, 2014, and 80 FR 60040, October 5, 2015, respectively.
After reviewing the comments, the EPA has determined that the comments do not raise issues that change our assessment regarding the approvability of the January 23, 2023 version of MDAQMD Rule 1160 into the California 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 January 23, 2023 version of Rule 1160 will replace the previously approved version of this rule in the SIP. As described in our proposal, this approval resolves all deficiencies forming the basis for our September 10, 2021 (86 FR 50643) limited disapproval of the prior version of Rule 1160. Our April 7, 2023 proposal (88 FR 20788) was accompanied by an interim final determination (88 FR 20776) deferring the imposition of sanctions (pursuant to CAA section 179 and 40 CFR 52.31) stemming from our September 10, 2021 limited disapproval. This final action now permanently terminates all sanctions clocks and federal implementation plan clocks triggered by our September 10, 2021 limited disapproval action. This final action also corrects regulatory text to clarify the applicable requirements for the MDAQMD portion of the California SIP.
**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 the Mojave Desert Air Quality Management District Rule 1160, Internal Combustion Engines, amended on January 23, 2023, which regulates NO <sub>X</sub> and VOC emissions from internal combustion engines. The EPA has made, and will continue to make, these documents available through *https://www.regulations.gov* 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).
**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:
• 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 October 27, 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, Incorporation by reference, Intergovernmental relations, Nitrogen oxides, Ozone, Reporting and recordkeeping requirements, Volatile organic compounds.
Dated: August 18, 2025.
Joshua F.W. Cook,
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**
**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 F—California**
**40 CFR Part 52**
2. Section 52.220 is amended by:
a. Adding paragraph (c)(121)(i)(G);
b. Revising paragraph (c)(207)(i)(D)( *5* ); and
c. Adding paragraphs (c)(518)(i)(A)( *12* ) and (c)(628).
The additions and revision read as follows:
§ 52.220
(c) * * *
(121) * * *
(i) * * *
(G) Previously approved on May 3, 1984, in paragraph (c)(121)(i)(C) of this section and now deleted without replacement for implementation in the Mojave Desert Air Quality Management District: Rule 1110.
(207) * * *
(i) * * *
(D) * * *
( *5* ) Previously approved on November 1, 1996, in paragraph (c)(207)(i)(D)( *3* ) of this section and now deleted with replacement in paragraph (c)(518)(i)(A)( *7* ) of this section: Rule 1160, adopted on October 26, 1994.
(518) * * *
(i) * * *
(A) * * *
( *12* ) Previously approved on September 10, 2021, in paragraph (c)(518)(i)(A)(7) of this section and now deleted with replacement in (c)(628)(i)(A)( *1* ) of this section: Rule 1160, “Internal Combustion Engines,” amended on January 22, 2018.
(628) The following regulation was submitted electronically on March 3, 2023, by the Governor's designee as an attachment to a letter dated February 17, 2023.
(i) *Incorporation by reference.*
(A) Mojave Desert Air Quality Management District.
( *1* ) Rule 1160, “Internal Combustion Engines,” amended on January 23, 2023.
( *2* ) [Reserved]
(B) [Reserved]
(ii) [Reserved]