Partial Approval and Partial Disapproval of Air Quality State Implementation Plans; Arizona; Prevention of Significant Deterioration Infrastructure Requirements for the 2012 Fine Particulate Matter National Ambient Air Quality Standard

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

Partial Approval and Partial Disapproval of Air Quality State Implementation Plans; Arizona; Prevention of Significant Deterioration Infrastructure Requirements for the 2012 Fine Particulate Matter National Ambient Air Quality Standard

Environmental Protection Agency (EPA).

Proposed rule; withdrawal.

The Environmental Protection Agency (EPA) is proposing to partially approve and partially disapprove a revision to the Arizona State implementation plan (SIP) as meeting the requirements of the Clean Air Act (CAA) for the implementation, maintenance, and enforcement of the 2012 fine particulate matter (PM2.5) national ambient air quality standard (NAAQS or "standards"). The EPA is proposing to approve the portions of Arizona's submission addressing prevention of significant deterioration (PSD) requirements in the permitting jurisdictions of the Arizona Department of Environmental Quality (ADEQ), Maricopa County Air Quality Department (MCAQD), and Pinal County Air Quality Control District (PCAQCD). The EPA is proposing to disapprove the portions of the Arizona submission addressing PSD requirements in the Pima County Department of Environmental Quality (PDEQ) permitting jurisdiction.

Comments must be received by September 8, 2026. As of July 21, 2026, the proposed rule published on June 13, 2024, at 89 FR 50245, is withdrawn insofar as it related to the PSD-related requirements of CAA sections 110(a)(2)(C), 110(a)(2)(D)(i)(II), 110(a)(2)(D)(ii), and 110(a)(2)(J).

The EPA has established a docket for this action under Docket ID No. EPA-R09-OAR-2026-3797. 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.

Michael Dorantes, Geographic Strategies and Modeling Section (AIR-2-2), EPA Region IX, 75 Hawthorne Street, San Francisco, CA; telephone number: (415) 972-3934; email address: [email protected].

Throughout this document, "we," "us," and "our" refer to the EPA.

Table of Contents

I. Statutory Requirements and the EPA's Considerations for Evaluating Infrastructure SIPs II. Background and Withdrawal of the EPA's Prior Proposed Partial Approval and Partial Disapproval of PSD Requirements Under CAA sections 110(a)(2)(C), 110(a)(2)(D)(i)(II), 110(a)(2)(D)(ii), and 110(a)(2)(J) III. The EPA's Updated Policy Rationale and Summary of the EPA's Proposed Partial Approval and Partial Disapproval IV. Request for Public Comments V. Statutory and Executive Order Reviews

I. Statutory Requirements and the EPA's Considerations for Evaluating Infrastructure SIPs

The EPA has historically referred to SIP submittals made for the purpose of satisfying the requirements of CAA sections 110(a)(1) and 110(a)(2) as "infrastructure SIP" (I-SIP) submittals. Although the term "infrastructure SIP" does not appear in the CAA, the EPA uses the term to distinguish this particular type of SIP submittal from submittals that are primarily intended to satisfy other SIP requirements under the CAA, such as "nonattainment SIP" or "attainment SIP" submittals intended to address the nonattainment planning requirements of CAA title I part D, "regional haze SIP" submittals required by the EPA rule to address the visibility protection requirements of CAA section 169A, and nonattainment new source review (NSR) permit program submittals to address the permit requirements of CAA title I part D. CAA section 110(a)(1) addresses the timing and general requirements for infrastructure SIP submittals, and CAA section 110(a)(2) provides details concerning the required content of these submittals. Notably, section 110(a)(1) of the Act clearly requires that each State adopt and submit an infrastructure SIP

for the implementation, maintenance, and enforcement of each NAAQS promulgated by the EPA, and that the EPA act on such SIP submittals, while CAA section 110(a)(2) provides an extensive list of required elements, some with provisions pertaining directly to legal authority, some with provisions pertaining to substantive program requirements, and some others which pertain to requirements for both authority and substantive program provisions. The EPA has historically asserted that this list of required provisions leads to ambiguities concerning what is required for inclusion in any SIP submittal subject to CAA section 110(a)(2). For example, CAA section 110(a)(2) requires that "each" SIP submittal must meet the list of requirements therein. However, the EPA has long noted that this literal reading of the statute is internally inconsistent and would create a conflict with the nonattainment provisions in CAA title I part D, which specifically address nonattainment SIP requirements.\1\ Section 110(a)(2)(I) of the CAA pertains to nonattainment SIP requirements, and part D addresses when attainment plan SIP submittals to address nonattainment area requirements are due. Moreover, CAA section 172(b) requires the EPA to establish a schedule for submittal of such plans for certain pollutants when the Administrator promulgates the designation of an area as nonattainment, and CAA section 107(d)(1)(B) allows up to two years, or in some cases three years, for such designations to be promulgated.\2\ As another example, CAA section 172(c)(7) requires that attainment plan SIP submittals required by part D have to meet only the "applicable requirements" of CAA section 110(a)(2). Thus, the EPA has interpreted this provision such that attainment plan SIP submittals must meet the requirements of CAA section 110(a)(2)(A) regarding enforceable emissions limits and control measures and CAA section 110(a)(2)(E)(i) regarding air agency resources and authority. As this example illustrates, each type of SIP submittal may implicate some elements of CAA section 110(a)(2) but not others, and rather than apply all the stated requirements of CAA section 110(a)(2) in a strict literal sense, as is the case for CAA section 110(a)(1), the EPA must determine how provisions of CAA section 110(a)(2) are applicable for a particular SIP submittal, including infrastructure SIPs.

\1\ See e.g. 70 FR 25162 at 70 FR 25163 through 25165 (May 12, 2005), explaining the relationship between the timing requirements of CAA section 110(a)(2)(D) versus CAA section 110(a)(2)(I). \2\ The EPA notes that this ambiguity within CAA section 110(a)(2) is heightened by the fact that various subparts of part D set specific dates for submittal of certain types of SIP submittals in designated nonattainment areas for various pollutants. Note, for example, that CAA section 182(a)(1) provides specific dates for submittal of emissions inventories for the ozone NAAQS. Some of these specific dates are necessarily later than three years after promulgation of the new or revised NAAQS.

In the context of a specific NAAQS, the EPA has also historically recognized that CAA section 110(a)(2) should also be read and interpreted in a logical context with respect to how infrastructure SIP submittal requirements should be structured. For example, the monitoring requirements that a State might need to meet in its infrastructure SIP submittal for purposes of CAA section 110(a)(2)(B) could be very different for different pollutants, because the content and scope of a State's infrastructure SIP submittal to meet this element might vary by NAAQS promulgation.\3\ Thus, the EPA notes that the best reading of CAA section 110(a)(2) can vary for each new or revised NAAQS, and therefore, requirements for the States' attendant infrastructure SIP submittals for each NAAQS may be different.

\3\ For example, implementation of the 1997 PM2.5 NAAQS required the deployment of a system of new monitors to measure ambient levels of new indicator species for the new NAAQS.

Given this, the EPA believes that it is appropriate to interpret the requirements of CAA section 110(a)(2) in the context of acting on individual SIP submittals. In other words, the EPA assumes that Congress could not have intended that each and every SIP submittal, regardless of the NAAQS in question or the history of SIP development for the relevant pollutant, would meet each of the requirements, or meet each of them in the same way. Therefore, the EPA reviews infrastructure SIP submittals against the list of elements in CAA section 110(a)(2), but only applies the required elements for the new or revised NAAQS. To this end, the EPA has issued guidance documents to make recommendations to States as to how their infrastructure SIP submittals can be structured to meet the requirements of CAA section 110(a)(2). The EPA most recently issued guidance for infrastructure SIPs on September 13, 2013 ("2013 Infrastructure SIP Guidance").\4\ One notable example from the 2013 Infrastructure SIP Guidance is how it gives simpler recommendations with respect to carbon monoxide than other NAAQS pollutants to meet the visibility requirements of CAA section 110(a)(2)(D)(i)(II) because carbon monoxide does not affect visibility. As a result, an infrastructure SIP submittal for any future new or revised NAAQS for carbon monoxide need only state this fact in order to address the visibility prong of CAA section 110(a)(2)(D)(i)(II).

\4\ Memorandum dated September 13, 2013, from Stephen D. Page, Director, Office of Air Quality and Planning Standards, U.S. EPA, Subject: "Guidance on Infrastructure State Implementation Plan (SIP) Elements under Clean Air Act Sections 110(a)(1) and 110(a)(2)."

Historically, the EPA has elected to use guidance in order to explain our current best interpretation of the relevant statute in lieu of promulgating regulations to govern CAA section 110(a)(2) infrastructure SIP requirements. However, the CAA ultimately governs what is required in infrastructure SIP submittals, regardless of whether EPA has provided advance guidance speaking to such requirements. Section 110(a)(1) of the CAA requires States to submit to the EPA, within three years after the promulgation of a new or revised NAAQS, a SIP submission that meets the applicable requirements of CAA section 110(a)(2) to provide for the implementation, maintenance, and enforcement of the new or revised NAAQS. CAA section 110(a)(2) includes several provisions that reference PSD-related requirements for the regulation of new and modified major stationary sources. Specifically: CAA section 110(a)(2)(C) requires States to include a program for the regulation of new and modified major stationary sources, including a permit program as required by title I part C of the CAA; CAA section 110(a)(2)(D)(i)(II) requires States to include "adequate provisions" to prohibit interference with any other State's PSD program; CAA section 110(a)(2)(D)(ii) requires States to include "adequate provisions" to ensure compliance with CAA section 126, which requires States to notify neighboring air agencies of potential impacts from new and modified major stationary sources of air pollution; and CAA section 110(a)(2)(J) requires States to meet the applicable requirements of part C (relating to PSD).

II. Background and Withdrawal of the EPA's Prior Proposed Partial Approval and Partial Disapproval of PSD Requirements Under CAA Sections 110(a)(2)(C), 110(a)(2)(D)(i)(II), 110(a)(2)(D)(ii), and 110(a)(2)(J)

On January 15, 2013 the EPA promulgated a revision to the PM2.5 NAAQS (2012 PM2.5 NAAQS), lowering

the level of the primary standard to 12.0 micrograms per cubic meter ([micro]g/m\3\), while maintaining the secondary standard.\5\ The ADEQ submitted two SIP revisions to address the infrastructure SIP requirements in CAA sections 110(a)(1) and 110(a)(2) for the 2012 PM2.5 NAAQS. This action pertains only to ADEQ's December 11, 2015 submittal, which addresses the PSD-related requirements of CAA section 110, titled "Arizona State Implementation Plan Revision for the 2012 Fine Particulate Matter (PM2.5) National Ambient Air Quality Standard" ("2012 PM2.5 I-SIP submittal").\6\

\5\ 78 FR 3086 (January 15, 2013). \6\ Letter dated December 11, 2015, from Eric Massey, Director, Air Quality Division, ADEQ, to Jared Blumenfeld, Regional Administrator, EPA Region IX, Subject: "Arizona Infrastructure State Implementation Plan for the 2012 PM2.5 National Ambient Air Quality Standards."

On June 13, 2024,\7\ the EPA proposed to partially approve and partially disapprove Arizona's 2012 PM2.5 I-SIP submittal with respect to the PSD-related requirements of CAA sections 110(a)(2)(C), 110(a)(2)(D)(i)(II), 110(a)(2)(D)(ii), and 110(a)(2)(J). Our proposed partial disapproval of these elements was based, at the time, on deficiencies we identified with respect to PSD permitting of greenhouse gases (GHGs) in all permitting jurisdictions in Arizona, as well as deficiencies with respect to PSD permitting of all NSR- regulated pollutants in Pima County. Our proposed partial approval for the PSD-related requirements of Arizona's submittal applied to those Arizona permitting jurisdictions with a SIP-approved PSD permitting program covering all other NSR-regulated pollutants. Our proposed action provided a 30-day public comment period during which we received four comments. One of the comments failed to raise issues germane to the proposed action, which we determined did not necessitate a response. There were three additional comments concerning the ADEQ's PSD permitting program.\8\

\7\ 89 FR 50245 (June 13, 2024). \8\ Id.

On December 18, 2025,\9\ we took final action on most of what we proposed in our June 13, 2024 rulemaking. However, we deferred action on the PSD-related requirements of CAA sections 110(a)(2)(C), 110(a)(2)(D)(i)(II), 110(a)(2)(D)(ii), and 110(a)(2)(J). Consequently, we did not respond to the comments concerning ADEQ's PSD permitting program.

\9\ 90 FR 59051 (December 18, 2025).

The EPA is soliciting public comments on this proposed rulemaking. We will accept comments from the public for the next 30 days. We will consider any comments received before taking final action.

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 review State choices, and approve those choices if they meet the minimum criteria of the Act. Accordingly, this proposed rulemaking proposes to partially approve and partially disapprove State law as meeting Federal requirements and does not impose additional requirements beyond those imposed by State law. Additional information about these statutes and Executive Orders can be found at https://www.epa.gov/laws-regulations/laws-and-executive-orders.

A. Executive Order 12866: Regulatory Planning and Review and Executive Order 13563: Improving Regulation and Regulatory Review (58 FR 51735, October 4, 1993)

This action is not a significant regulatory action and was therefore not submitted to the Office of Management and Budget (OMB) for review.

B. Executive Order 14192: Unleashing Prosperity Through Deregulation (90 FR 9065, February 6, 2025)

This action is not expected to be an Executive Order 14192 regulatory action because this action is not significant under Executive Order 12866.

C. Paperwork Reduction Act (PRA) (44 U.S.C. 3501et seq.)

This action does not impose an information collection burden under the PRA because this action does not impose additional requirements beyond those imposed by State law.

D. Regulatory Flexibility Act (RFA) (5 U.S.C. 601et seq.)

I certify that this action will not have a significant economic impact on a substantial number of small entities under the RFA. This action will not impose any requirements on small entities beyond those imposed by State law.

E. Unfunded Mandates Reform Act (UMRA) (Pub. L. 104-4)

This action does not contain any unfunded mandate as described in UMRA, 2 U.S.C. 1531-1538, and does not significantly or uniquely affect small governments. This action does not impose additional requirements beyond those imposed by State law. Accordingly, no additional costs to State, local, or Tribal governments, or to the private sector, will result from this action.

This action does not have federalism implications. It will not have substantial direct effects on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government.

G. Executive Order 13175: Coordination With Indian Tribal Governments (65 FR 67249, November 9, 2000)

This action does not have Tribal implications, as specified in Executive Order 13175, because 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, and will not impose substantial direct costs on Tribal governments or preempt Tribal law. Thus, Executive Order 13175 does not apply to this action.

H. Executive Order 13045: Protection of Children From Environmental Health Risks and Safety Risks (62 FR 19885, April 23, 1997)

The EPA interprets Executive Order 13045 as applying only to those regulatory actions that concern environmental health or safety risks that the EPA has reason to believe may disproportionately affect children, per the definition of "covered regulatory action" in section 2-202 of the Executive Order. Therefore, this action is not subject to Executive Order 13045 because it merely proposes to partially approve and partially disapprove State law as meeting Federal requirements. Furthermore, the EPA's Policy on Children's Health does not apply to this action.

I. Executive Order 13211: Actions That Significantly Affect Energy Supply, Distribution, or Use (66 FR 28355, May 22, 2001)

This action is not subject to Executive Order 13211, because it is not a significant regulatory action under Executive Order 12866.

J. National Technology Transfer and Advancement Act (NTTAA) (15 U.S.C. 272 Note)

Section 12(d) of the NTTAA directs the EPA to use voluntary consensus standards in its regulatory activities unless to do so would be inconsistent with applicable law or otherwise impractical. The EPA believes that this action is not subject to the requirements of section 12(d) of the NTTAA because application of those requirements would be inconsistent with the CAA.

List of Subjects in 40 CFR Part 52

Environmental protection, Air pollution control, Incorporation by reference, Intergovernmental relations, Nitrogen Dioxide, Particulate matter, Reporting and recordkeeping requirements, Volatile organic compounds.

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

Dated: July 21, 2026. Michael Martucci, Acting Regional Administrator, Region IX. [FR Doc. 2026-16083 Filed 8-5-26; 8:45 am] BILLING CODE 6560-50-P