Air Plan Approval; Montana: Infrastructure Requirements for the 2015 Ozone National Ambient Air Quality Standards

<RULE> ENVIRONMENTAL PROTECTION AGENCY <CFR>40 CFR Part 52</CFR> <DEPDOC>[EPA-R08-OAR-2019-0418; FRL-12875-02-R8]</DEPDOC> <SUBJECT>Air Plan Approval; Montana: Infrastructure Requirements for the 2015 Ozone National Ambient Air Quality Standards</SUBJECT> <HD SOURCE="HED">AGENCY:</HD> Environmental Protection Agency (EPA). <HD SOURCE="HED">ACTION:</HD> Final rule. <SUM> <HD SOURCE="HED">SUMMARY:</HD> The Environmental Protection Agency (EPA) is approving elements of a state implementation plan (SIP) submission from Montana regarding the infrastructure requirements of the Clean Air Act (CAA) for the 2015 8-hour ozone National Ambient Air Quality Standards (NAAQS). The infrastructure requirements are designed to ensure that the structural components of each state's air quality management program are adequate to meet the state's responsibilities under the CAA. Additionally, EPA is finalizing approval of Montana's request to update their SIP to incorporate the most recent version of EPA's “Guidelines on Air Quality Models.” EPA is taking this action pursuant to the CAA. </SUM> <EFFDATE> <HD SOURCE="HED">DATES:</HD> This rule is effective on December 18, 2025. </EFFDATE> <HD SOURCE="HED">ADDRESSES:</HD> EPA has established a docket for this action under Docket ID No. EPA-R08-OAR-2019-0418. All documents in the docket are listed on the <E T="03">https://www.regulations.gov</E> website. Although listed in the index, some information is not publicly available, <E T="03">e.g.,</E> 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 <E T="03">https://www.regulations.gov,</E> or please contact the person identified in the <E T="02">FOR FURTHER INFORMATION CONTACT</E> section for additional availability information. <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> Amrita Singh, Air and Radiation Division, EPA, Region 8, Mailcode 8ARD-IO, 1595 Wynkoop Street, Denver, Colorado 80202-1129, telephone number: (303) 312-6103, email address: <E T="03">singh.amrita@epa.gov.</E> </FURINF> <SUPLINF> <HD SOURCE="HED">SUPPLEMENTARY INFORMATION:</HD> Throughout this document “we,” “us,” and “our” means EPA. <HD SOURCE="HD1">I. Background</HD> Under sections 110(a)(1) and (2) of the CAA, each state is required to submit a SIP that provides for the implementation, maintenance, and enforcement of a revised primary or secondary NAAQS or standard. CAA sections 110(a)(1) and (2) requires each state to make a new SIP submission within three years after EPA promulgates a new or revised NAAQS for approval into the existing federally approved SIP to assure that the SIP meets the applicable requirements for new and revised NAAQS. On July 16, 2025 EPA proposed to approve all elements of a SIP submission from the Montana Department of Environmental Quality (MDEQ) submitted on October 1, 2018 except for those previously approved in 87 FR 21578. We proposed approval for the following CAA section 110(a)(2) infrastructure elements for the 2015 ozone NAAQS: (A), (B), (C), (D)(i)(II), (D)(ii), (E), (F), (G), (H), (J), (K), (L) and (M). Concurrently, EPA also proposed to approve revisions to appendix W submitted on December 28, 2022. An explanation of the CAA requirements, detailed analysis of the revisions, and EPA's reasons for proposing approval were provided in the proposed rulemaking (90 FR 31911). <HD SOURCE="HD1">II. Response to Comments</HD> During the public comment period of EPA's July 16, 2025, proposed rulemaking, EPA received one anonymous comment in support of our action and one anonymous adverse comment. A summary of the comments and EPA's response are provided below. <E T="03">Comment:</E> The commentor urged EPA to consider the role of CO <E T="52">2</E> emissions and climate change in ozone formation when reviewing the Montana infrastructure SIP for the 2015 ozone NAAQS. The commentor stated that climate-change driven factors such as increased temperatures, biogenic emissions, and wildfire activity is projected to influence both the frequency and severity of ozone exceedances and suggested that infrastructure SIPs should acknowledge the long-term planning risks associated with climate-driven ozone trends. <E T="03">Response:</E> EPA appreciates the commenter's concern regarding the influence of CO <E T="52">2</E> emissions and climate change on ozone formation and air quality. However, the scope of this action is limited to determining whether Montana's SIP meets the infrastructure requirements of CAA section 110(a)(1) and (2) for the 2015 ozone NAAQS. These requirements address the basic structural elements of a state's air quality management program. EPA's review of Montana's SIP submission is limited to the applicable statutory and regulatory requirements for infrastructure SIPs related to the 2015 ozone NAAQS, which the submission satisfies. Therefore, the considerations raised by the commentor are outside the scope of this rulemaking. <E T="03">Comment:</E> The commentor supported EPA's proposal to approve Montana's infrastructure SIP submission for the 2015 ozone NAAQS, noting that Montana has met the CAA's structural requirements. The commentor encouraged EPA and the Montana Department of Environmental Quality to ensure strong public education, transparency, and community outreach efforts. <E T="03">Response:</E> EPA appreciates the commentor's support for this action. The scope of this action is limited to evaluating whether Montana's SIP submission meets the infrastructure requirements of the CAA section 110(a)(1) and (2) for the 2015 Ozone NAAQS. EPA has determined that Montana's SIP submission satisfies the applicable statutory and regulatory requirements for this action. <HD SOURCE="HD1">III. Final Action</HD> EPA is approving the infrastructure SIP elements listed in table 1 below. These elements were included in a SIP submission from Montana certifying that its current SIP is sufficient to meet the required elements under section 110(a)(1) and (2) for the 2015 ozone NAAQS. Additionally, EPA is approving the revisions to appendix W submitted by the State of Montana on December 28, 2022. <GPOTABLE COLS="2" OPTS="L2,nj,i1" CDEF="s100,xs150"> <TTITLE>Table 1—2015 Ozone NAAQS Infrastructure SIP Elements</TTITLE> <CHED H="1">Elements</CHED> <CHED H="1">Approval status</CHED> <ROW> <ENT I="01">(A): Emission Limitations and Other Control Measures</ENT> <ENT>Approve.</ENT> </ROW> <ROW> <ENT I="01">(B): Ambient Air Quality Monitoring/Data System</ENT> <ENT>Approve.</ENT> </ROW> <ROW> <ENT I="01">(C): Program for Enforcement of Control Measures; minor NSR; PSD</ENT> <ENT>Approve.</ENT> </ROW> <ROW> <ENT I="01">(D)(i)(I): Prong 1 Interstate Transport—significant contribution</ENT> <ENT>Previously approved in 87 FR 21578.</ENT> </ROW> <ROW> <ENT I="01">(D)(i)(I): Prong 2 Interstate Transport—interference with maintenance</ENT> <ENT>Previously approved in 87 FR 21578.</ENT> </ROW> <ROW> <ENT I="01">(D)(i)(II): Prong 3 Interstate Transport—PSD</ENT> <ENT>Approve.</ENT> </ROW> <ROW> <ENT I="01">(D)(i)(II): Prong 4 Interstate Transport—visibility</ENT> <ENT>Previously approved in 87 FR 21578.</ENT> </ROW> <ROW> <ENT I="01">(D)(ii): Interstate and International Pollution Abatement</ENT> <ENT>Approve.</ENT> </ROW> <ROW> <ENT I="01">(E): Adequate Personnel. Funding, and Authority; State Boards; Local Implementation</ENT> <ENT>Approve.</ENT> </ROW> <ROW> <ENT I="01">(F): Stationary Source Monitoring</ENT> <ENT>Approve.</ENT> </ROW> <ROW> <ENT I="01">(G): Emergency Authority; Emergency Episode Plans</ENT> <ENT>Approve.</ENT> </ROW> <ROW> <ENT I="01">(H): Future SIP Revisions</ENT> <ENT>Approve.</ENT> </ROW> <ROW> <ENT I="01">(J): Consultation with Government Officials, Public Notification, PSD and Visibility Protection</ENT> <ENT>Approve.</ENT> </ROW> <ROW> <ENT I="01">(K): Air Quality Modeling/Data</ENT> <ENT>Approve.</ENT> </ROW> <ROW> <ENT I="01">(L): Permitting Fees</ENT> <ENT>Approve.</ENT> </ROW> <ROW> <ENT I="01">(M): Consultation/Participation by Affected Local Entities</ENT> <ENT>Approve.</ENT> </ROW> </GPOTABLE> <HD SOURCE="HD1">IV. Incorporation by Reference</HD> In this document, EPA is finalizing regulatory text that includes incorporation by reference. In accordance with requirements of 1 CFR 51.5, EPA is finalizing the incorporation by reference of appendix W revisions submitted by the State of Montana as discussed in the previously mentioned proposed rulemaking that can be found in the <E T="04">Federal Register</E> at 90 FR 31911. EPA has made, and will continue to make, these materials generally available through <E T="03">https://www.regulations.gov</E> and at the EPA Region 8 Office (please contact the person identified in the <E T="02">FOR FURTHER INFORMATION CONTACT</E> section of this preamble for more information). <HD SOURCE="HD1">V. Statutory and Executive Order Reviews</HD> 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, 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 Ex ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 16k characters. Full document text is stored and available for version comparison. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━