SUPPLEMENTARY INFORMATION:

Throughout this document, “we,” “us,” and “our” 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:

ADEQ—Arizona Department of Environmental Quality

AZRBOB—Arizona Reformulated Blendstock for Oxygenate Blending

CAA—Clean Air Act

CARBOB—California Reformulated Blendstock for Oxygenate Blending

CBG—Cleaner Burning Gasoline

CBI—confidential business information

CO—carbon monoxide

EPA—Environmental Protection Agency

GSA—Gasoline Set-aside

SIP—State Implementation Plan

TSD—Technical Support Document

WMSD—Weights and Measures Services Division

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. Summary of Proposed Action

III. EPA Action and Public Comments

IV. Incorporation by Reference

V. Statutory and Executive Order Reviews

I. Executive Summary

A. What action is the EPA taking?

The EPA is approving a revision to the Arizona SIP submitted by the ADEQ. This revision includes statutes and regulations amending the CBG program and the Winter Oxygenated Fuel program to control CO emissions in the Tucson area, and it repeals the GSA Program. This action updates the existing SIP-approved CBG program with revisions that have been adopted and implemented by the State to clarify requirements, update references, and enhance flexibility of the program, and it will not impose any additional costs or regulatory burdens.

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

Under the Clean Air Act (CAA), the EPA Administrator is required to approve a SIP submission that complies with the provisions of the CAA and applicable Federal regulations.^[1] In reviewing SIP submissions, the EPA's role is to approve State choices, provided they meet the relevant 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.

The EPA is approving this submittal under CAA section 110. Specifically, CAA section 110(k) requires SIPs to meet certain procedural requirements and requires the EPA to approve or disapprove SIP submissions. CAA section 110(l) requires States to provide public notice and an opportunity for public hearing of SIP revisions prior to their submittal and prohibits the EPA from approving any SIP revisions that would interfere with attainment or maintenance of National Ambient Air Quality Standards (NAAQS), reasonable further progress, or other applicable requirements of the CAA. The EPA finds that this SIP submittal meets all the applicable CAA requirements and the Agency approves it under CAA section 110(k)(3).

II. Summary of Proposed Action

On June 23, 2026,^[2] the EPA proposed to approve the submitted statutes and rules listed in table 1 of this preamble below into the Arizona SIP. These revisions were adopted by the Arizona State Legislature and the Weights and Measures Services Division (WMSD) of the Arizona Department of Agriculture and submitted by ADEQ to the EPA on June 17, 2021.^[3] Supplemental information was submitted in 2025.^[4] ADEQ is the Governor's designee for submitting official revisions to the Arizona SIP to the EPA. Table 1 of this preamble also identifies the dates that statutes and rules became effective locally and the dates that they were submitted by ADEQ.^[5]

( printed page 66005)

The June 23, 2026 proposal for this action also identifies statutes and rules that are superseded by the new submittal and accordingly proposed for deletion from the Arizona SIP.^[6]

III. EPA Action and Public Comments

The EPA's proposed action provided a 30-day public comment period. During this period, we received one comment letter that did not oppose the proposed approval, and supported the accuracy and completeness of the record. Issues raised in this comment letter are summarized with responses below.

Comment 1: The commenter suggested that a citation, included in footnote 63 of the technical support document (TSD) for the proposed action, to a December 22, 2016 letter from the EPA to Gevo, Inc. should be corrected to refer instead to the EPA's June 12, 2018 registration approval letter for isobutanol to Butamax Advanced Biofuels LLC.

Response 1: The EPA agrees that the June 12, 2018 Butamax registration letter is the more appropriate citation. The EPA is including the correct version of the letter in the docket for this action.

Comment 2: The commenter addressed the EPA's proposed approval of a 2017 version of AAC R3-7-708 that includes references to “ethanol” to describe requirements for oxygenates added to gasoline. As the commenter noted, Arizona later corrected these references to specify application of these requirements to oxygenates generally (in addition to ethanol) in a version of the rule that has not yet been submitted for SIP approval. The commenter suggested that the EPA should either decline to approve this version of the rule or state expressly in the final rule's regulatory text (and not only in the TSD) that the enforceable scope of R3-7-708 extends to isobutanol blending, notwithstanding the section's ethanol-specific terms.

Response 2: The EPA acknowledges the commenter's concern regarding the enforceable scope of AAC R3-7-708 and the presence of ethanol-specific language in the submitted version of R3-7-708. As the EPA stated in the TSD for our proposed rulemaking:

( printed page 66006)

As a general matter, the CAA requirements for oxygenated fuel are oxygenate-neutral, in that they do not require any specific oxygenate to be used. Consistent with these requirements, the EPA has previously communicated to ADEQ that its CBG program regulations should allow oxygenates other than ethanol, and the State revised its regulations in 2018 to make this change.^[7]

The EPA also explained that the language in the submitted version of AAC R3-7-708 was nonetheless acceptable:

In the context of the broader CBG program, which clearly specifies that oxygenates other than ethanol to be used, we consider this language to be acceptable because it is apparent that the references to ethanol are meant to address general requirements for oxygenates and are not intended to limit the choice of oxygenate for oxygenated fuels.^[8]

The EPA reiterates here that the scope of our approval of this provision extends to all oxygenates that the Agency has registered under CAA section 211(a), which is consistent with the broader context of the submitted CBG program, notwithstanding the rule's references to ethanol. As the EPA noted in the TSD for our proposed action, the State has indicated that it plans to submit a revised version of this rule in its next SIP submittal.^[9]

Comment 3: The commenter requested that the EPA state an individual basis for each of the nine categories of changes collectively described as “administrative in nature.” The commenter noted particularly the CARBOB Model substitution and the blendstock recertification allowance, which they characterize as introducing new compliance pathways.

Response 3: The TSD identifies multiple changes as administrative in nature and provides a general basis for the approval of such changes.^[10] With respect to the CARBOB Model substitution and the blendstock recertification allowance, the Agency's proposed approval of the submitted revisions is based on the fact that the underlying measures have already been approved by the EPA and the measures have previously approved compliance pathways.^[11] The submitted revisions add SIP-strengthening compliance flexibilities to previously approved regulations. The EPA has considered the underlying provisions individually in reaching this conclusion and has determined that the submitted revisions are approvable.

The EPA notes that the changes the Agency is acting on and approving strengthen the SIP by providing greater clarity to the regulated public. As stated in the TSD for the proposed action:

The EPA has long acknowledged that SIP revisions to an approved state fuel program that are administrative in nature because they improve and strengthen an existing SIP-approved fuel program are within the scope of the previous necessity finding and do not require another “necessity” demonstration under CAA section 211(c)(4)(C)(i).^[12]

Comment 4: The commenter suggested that the EPA should clarify its expectations for the interaction between the proposed SIP approval and the EPA's national waiver of Federal enforcement which applies to state boutique fuel requirements for gasoline, including specifically whether the EPA anticipates the waiver lapsing before or shortly after this action is finalized, and what compliance transition, if any, regulated parties should expect if Federal enforcement of the approved Arizona CBG requirements resumes on short notice.

Response 4: The comment is beyond the scope of this rulemaking. The present action addresses only whether the rules submitted by Arizona comply with all applicable CAA requirements for a SIP submittal.

Comment 5: The commenter suggested that the EPA should identify a specific timeline or commitment for review of the 2023 amendments, and that the Agency should clarify how the gap in the federally enforceable SIP and the requirements that are currently in effect at the State level will be addressed and over what timeframe.

Response 5: The present action addresses only the rules submitted by Arizona. Once approved into the SIP, these rules will be federally effective and enforceable upon all regulated parties. As noted in response to Comment 2, Arizona has indicated that it plans to submit a revised version of Rule R3-7-708 in its next SIP submittal.

Comment 6: The commenter observed that the publication date of the Federal Register publication cited in footnote 3 of the proposal should be May 16, 1988,” instead of “May 16, 1998,” and suggested that this should be changed in the final rule.

Response 6: The EPA agrees that the date for this citation was incorrectly listed in the proposed rulemaking. The EPA hereby clarifies that the correct citation is “53 FR 17378 (May 16, 1988).”

No comments were submitted that changed the EPA's assessment of the submitted rules as described in our proposed action. Therefore, the EPA continues to find that the submitted rules should be approved into the Arizona SIP because they fulfill all relevant CAA requirements. Therefore, as authorized in CAA section 110(k)(3), the EPA is approving the submitted statutes and rules into the Arizona 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 incorporating by reference the statutes and rules as described in section II of this preamble: new sections ARS 3-3401 (1), (2), (4), (17), (19), (20), (22), (24), (27), (28), (29), (32); ARS 3-3433 (A)-(I); ARS 3-3473 (A)(1), (B)(4), (C); ARS 3-3475; ARS 3-3491; ARS 3-3492; ARS 3-3493; ARS 3-3495; AAC R3-7-101; AAC R3-7-701; AAC R3-7-702 (A)(1)-(13), (A)(15); AAC R3-7-708; AAC R3-7-716; AAC R3-7-749; AAC R3-7-750; AAC R3-7-751; AAC R3-7-752; AAC R3-7-753; AAC R3-7-754; AAC R3-7-755; AAC R3-7-756; AAC R3-7-757; AAC R3-7-759; AAC R3-7-760; AAC R3-7-761; AAC R3-7-762; AAC R3-7 Table A; AAC Title 3, Chapter 7, Article 7, Table 1; and AAC Title 3, Chapter 7, Article 7, Table 2. These statues and rules amend the Arizona Cleaner Burning Gasoline (CBG) program, which is a control measure in the greater Phoenix metropolitan area to reduce emissions of ozone-forming pollutants, carbon monoxide, and particulate matter. The EPA has made, and will continue to make, these materials available through 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). 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 EPA's approval, and will be incorporated by reference in the next update to the SIP compilation.

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 ( printed page 66007) 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 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 approves 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 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 December 18, 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 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: