SUPPLEMENTARY INFORMATION:

Throughout this document, the use of “we,” “us,” or “our” is intended to refer to the EPA. We use multiple abbreviations and terms in this final rule. While this list may not be exhaustive, for ease of reading and for reference purposes, the EPA defines the following terms and acronyms here:

CAA Clean Air Act

CARB California Air Resources Board

CBI Confidential Business Information

CFR Code of Federal Regulations

DOT U.S. Department of Transportation

EMFAC EMission FACtor

EPA U.S. Environmental Protection Agency

FCOG Fresno Council of Governments

FR Federal Register

KCAG Kings County Association of Governments

KCOG Kern Council of Governments

MCAG Merced County Association of Governments

MCTC Madera County Transportation Commission

MPO Metropolitan Planning Organization

NAAQS National Ambient Air Quality Standards

NO_X  Nitrogen Oxides

PM_2.5  Particulate matter less than 2.5 µm in diameter

RFP Reasonable Further Progress

SIP State Implementation Plan

SJCOG San Joaquin Council of Governments

SJV San Joaquin Valley

StanCOG Stanislaus Council of Governments

TCAG Tulare County Association of Governments

TIP Transportation Improvement Program

VOC Volatile Organic Compounds

Table of Contents

I. Executive Summary

A. What action is the EPA taking?

B. What is the legal authority and what are the requirements?

II. Background and Proposed Action

III. Public Comments

IV. Final Action

V. Statutory and Executive Order Reviews

I. Executive Summary

A. What action is the EPA taking?

The EPA is taking final action to approve a revision to the SJV portion of the California SIP for the 2008 8-hour ozone NAAQS. The revision includes an update to the SJV subarea budgets for NO_X and VOC for the 2008 8-hour ozone NAAQS. Upon the effective date of the EPA's approval, the revised budgets will supersede the existing approved SJV subarea budgets for the 2008 ozone NAAQS that were based on an earlier emissions model.

B. What is the legal authority and what are the requirements?

The EPA has legal authority to approve, disapprove, or conditionally approve, in whole or in part, submissions of SIPs and SIP revisions under CAA section 110(k). The applicable requirements for this type of action include those in CAA sections 110(a)(1) and (2), CAA section 110(l), 40 CFR 51.102, and 40 CFR 93.118(e)(4).

CAA sections 110(a)(1) and (2) and 40 CFR 51.102 establish certain procedural requirements on States for adoption and submittal of SIPs and SIP revisions to the EPA to meet CAA requirements. CAA section 110(l) prohibits the EPA from approving SIP revisions that would interfere with any applicable requirements concerning attainment and reasonable further progress (RFP) or any other applicable requirement of the Act.

Generally, the EPA reviews budgets for approval in the context of the Agency's review of a control strategy. A State may revise the motor vehicle emissions inventories and related budgets without revising its entire SIP, consistent with CAA section 110(l), if: (1) the SIP continues to meet applicable requirements when the previous motor vehicle emissions inventories are replaced with new base year and milestone, attainment, or maintenance year inventories based on a more recent emissions model; and (2) the State can document that growth and control strategy assumptions for non-motor vehicle sources continue to be valid and any minor updates do not change the overall conclusions of the SIP.^[1]

At 40 CFR 93.118(e)(4), the EPA specifies certain other minimum requirements for budgets to be found adequate or approved.

II. Background and Proposed Action

On July 9, 2026, the EPA proposed,^[2] under CAA section 110(k)(3), to approve a revision to the California SIP submitted by the California Air Resources Board (CARB) on April 30, 2026.^[3] The SIP submittal revises budgets applicable to control strategy plans for the SJV for the 2008 ozone standards.^[4] CARB developed the revised budgets using EMFAC2021,^[5] with off-model adjustment factors approved by the EPA in November 2025 (“November 2025 Adjustment Factors”),^[6] and travel activity projections provided by the SJV Metropolitan Planning Organizations (MPOs) consistent with the 2025 Federal Transportation Improvement Program (TIP).^[7] As such, the revised ( printed page 58025) budgets reflect the most recent planning forecasts and are based on the most recent emission factor data and approved calculation methods.

The EPA previously approved budgets for the 2008 ozone standards for the SJV nonattainment area. The ozone precursor budgets were included as part of the EPA's approval of three SIP revisions submitted by CARB to address the nonattainment planning requirements for the SJV for the 2008 ozone NAAQS, including the RFP and attainment demonstrations. These SIP revisions include the “San Joaquin Valley 2016 Plan for the 2008 8-Hour Ozone Standard” (“2016 Ozone Plan”) and the portions of the “Revised Proposed 2016 State Strategy for the State Implementation Plan” (“2016 State SIP Strategy”) and “2018 Updates to the California State Implementation Plan” (“2018 SIP Update”) that pertain to the SJV for the 2008 ozone NAAQS.^[8] Collectively, we refer to the approved SIP revisions for SJV for the 2008 ozone NAAQS as the “2016 SJV Ozone SIP.” The previously approved ozone budgets were developed using EMFAC2014.

In our July 9, 2026 proposed rule, we reviewed the revised budgets in the April 30, 2026 submittal, evaluated them for compliance with statutory and regulatory requirements, and concluded that they meet all applicable requirements. More specifically, we found that the 2016 SJV Ozone Plan will continue to meet applicable requirements for RFP and attainment when the existing approved, EMFAC2014-based budgets are replaced with the revised budgets based on EMFAC2021 with the November 2025 adjustment factors, and that the changes in the growth and control strategy assumptions for non-motor vehicle sources do not change the overall conclusions of the 2016 SJV Ozone SIP.

As such, we found that approval of the revised NO_X and VOC budgets from the 2026 Valley Ozone Budget Update for 2026, 2029, and 2031 as shown in Table 1 would not interfere with attainment or RFP or any other requirement of the Act and would thereby comply with CAA section 110(l). We proposed to approve the revised budgets on that basis.

In our proposed rule, the EPA also proposed to limit the duration of the approval of the budgets in the 2026 Valley Ozone Budget Update. We did so in light of CARB's request to limit the duration of the revised budgets and CARB's explanation for why the budgets in the 2026 Valley Ozone Budget Update may become outdated and should be replaced upon an EPA adequacy finding for further revised budgets. In short, CARB has requested that we limit the duration of the approval of the budgets because CARB expects the next version of EMFAC to estimate higher emissions for certain onroad motor vehicle categories and for certain areas of the State, necessitating updates to the budgets once the next version of EMFAC is submitted to and approved by the EPA.

If the EPA approves the future EMFAC model version, CARB explains that the budgets from the 2026 Valley Ozone Budget Update, for which we are finalizing approval in this action, may become outdated and will need to be revised. In addition, CARB states that, without the ability to replace the budgets using the budget adequacy process, the benefits of using the updated data may not be realized for a year or more after the updated SIP (with the future budgets) is submitted, due to the length of the SIP approval process.

Please see our July 9, 2026 proposed rule for more information concerning the background for this action and for a more detailed discussion of the rationale for approval of the revised budgets.

III. Public Comments

Our July 9, 2026 proposed rule provided a 30-day public comment period, which closed on August 10, 2026. During this period, we received comments from five commenters. Two of the commenters refer to air pollution generally, but their comments are not germane to the proposed action. The three other commenters generally support the proposed action, but express certain potential objections, make certain recommendations or request clarification of certain statements in the proposed rule.^[9] In the following paragraphs, we present the comments verbatim and provide our responses. The comment submissions are included in the docket for this action.

Comment 1. “It is important to note that the revised VOC budgets slightly increase in Stanislaus County across the three covered years, as well as in Tulare County during '26 and '29. The updated non-road emissions are also greater than prior estimates. Although reductions ( printed page 58026) elsewhere in the proposal offset these increases, considering regional totals alone may conceal more local yet nevertheless important changes.”

Response 1. VOCs are precursors to formation of ambient ozone and particulate matter less than 2.5 µm in diameter (PM_2.5), but the associated impact on ambient concentrations occurs well downwind of the source of VOCs, rather than in the locality of the source, and impact depends upon the amount of sunlight present and atmospheric mixing as well as other meteorological and topographic factors. In addition, motor vehicle emissions are distributed throughout the road network of a given county, as well as the nonattainment area. For these reasons, we expect that the slight increases in VOCs in certain counties relative to the budgets that were previously approved would not have an adverse local effect.

Comment 2. “Additionally, it is my stance that prior to approving future replacements via an adequacy finding, the EPA should public comparisons at both the county and regional level, as well as explain any material increases. The agency should also confirm that any new budgets remain consistent with reasonable progress and attainment requirements.”

Response 2. The EPA's process for determining adequacy of a budget consists of three steps: (1) Providing public notification of a SIP submission, (2) providing the public the opportunity to comment on the budget during a public comment period, and, (3) making a finding of adequacy or inadequacy.^[10]

We would expect the SIP revision containing the future budget replacements to compare the approved budgets with the submitted budgets, both on a county-level basis as well as a regional basis, similar to the types of comparisons CARB has provided in the 2026 Valley Ozone Budget Update.^[11]

For the EPA to find budgets adequate, the budgets must meet, at a minimum, the EPA's adequacy criteria (40 CFR 93.118(e)(4)). To meet these requirements, the budgets must be consistent with the attainment and RFP requirements and reflect all of the motor vehicle control measures contained in the attainment and RFP demonstrations.^[12]

As such, an EPA finding of adequacy for any replacement budgets relies upon both analysis of public comments on the submitted budgets and on the information included by CARB in support of the submitted budgets and is based on EPA's determination that the submitted budgets are consistent with the RFP and attainment demonstration requirements for the 2008 ozone NAAQS in the San Joaquin Valley.

Comment 3. “The updated model generally lowers the total NO_X and VOC emissions budgets, which seems like a step in the right direction. However, some individual counties may still see small increases in certain categories. I think the EPA should clearly explain why those increases happen so residents can understand whether they come from changes in traffic, updated data, or the model itself.”

Response 3. In 2021, California released a new version of its motor vehicle emissions model, EMFAC2021. CARB notes that, due to updated data and methodologies, EMFAC2021 estimates higher overall emissions from the on-road vehicle population in many areas of the State compared to prior versions of the model.^[13] With respect to the SJV, motor vehicle projections made using EMFAC2021 are higher in certain counties for VOC as compared with the corresponding estimates made using EMFAC2014 but lower for all the counties for NO_X.

IV. Final Action

For the reasons discussed in the July 9, 2026 proposed rule and summarized in this final rule, the EPA is approving the 2026 Valley Ozone Budget Update submitted by CARB on April 30, 2026, and all the revised subarea motor vehicle emissions budgets contained therein for the SJV area for the 2008 ozone NAAQS as a revision to the California SIP. More specifically, the EPA is approving, under CAA section 110(k)(3), the 2026 Valley Ozone Budget Update and the revised VOC and NO_X budgets shown in Table 1 of this final rule for 2026, 2029, and 2031 for the 2008 ozone standards.

With our final approval, we are also limiting the duration of the approval of the budgets to last only until the effective date of an adequacy finding by the EPA for any subsequently submitted budgets for the same CAA purpose and years. We are doing so at CARB's request consistent with 40 CFR 93.118(e)(1).

Lastly, on the effective date of this action, the previously approved budgets for the 2008 ozone standard will no longer be applicable for transportation conformity purposes, and the SJV MPOs and the U.S. Department of Transportation (DOT) must use the revised budgets for future transportation conformity determinations.

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 a State plan 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 underExecutive Order 12866 (58 FR 51735, October 4, 1993);
• Is not anExecutive Order 14192 (90 FR 9065, February 6, 2025) regulatory action because this action is not significant 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 inExecutive Order 13132 (64 FR 43255, August 10, 1999);
• Is not subject toExecutive Order 13045 (62 FR 19885, April 23, 1997) because it proposes to approve a State program;
• Is not a significant regulatory action subject toExecutive 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 ( printed page 58027) 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 November 13, 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 it 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).)

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

For the reasons stated in the preamble, the EPA amends 40 CFR part 52 as follows:

91 FR 58023