Approval and Promulgation of Implementation Plans; State of Utah; Salt Lake City and Provo, Utah PM2.5 Redesignations to Attainment and Utah State Implementation Plan Revisions

<RULE> ENVIRONMENTAL PROTECTION AGENCY <CFR>40 CFR Part 52 and 81</CFR> <DEPDOC>[EPA-R08-OAR-2020-0098; FRL-12594-02-R8]</DEPDOC> <SUBJECT> Approval and Promulgation of Implementation Plans; State of Utah; Salt Lake City and Provo, Utah PM <E T="0735">2.5</E> Redesignations to Attainment and Utah State Implementation Plan Revisions </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 the redesignation of the Salt Lake City, Utah and Provo, Utah nonattainment areas (NAAs) to attainment for the 2006 24-hour fine particulate matter with an aerodynamic diameter less than or equal to a nominal 2.5 microns (PM <E T="52">2.5</E> ) National Ambient Air Quality Standard (NAAQS), and also approving multiple related State Implementation Plan (SIP) submissions. We are approving SIP revisions submitted by the State of Utah on January 19, 2017; February 4 and 15, 2019; January 13, 2020; December 17, 2020; and July 15, 2025. These SIP submissions include revisions to Utah Administrative Code (UAC) section R307-110; revisions to Utah state law SIP sections IX.H.11, 12, and 13; best available control measures/best available control technologies (BACM/BACT) PM <E T="52">2.5</E> determinations for Salt Lake City and Provo; maintenance plans for the Salt Lake City and Provo areas for PM <E T="52">2.5</E> including motor vehicle emissions budgets used for transportation conformity purposes; and the request for redesignation under the 2006 24-hour PM <E T="52">2.5</E> standard. The EPA is also finding the budgets adequate for transportation conformity purposes. The EPA is taking this action pursuant to the Clean Air Act (CAA or the Act). </SUM> <EFFDATE> <HD SOURCE="HED">DATES:</HD> This rule is effective on December 19, 2025. </EFFDATE> <HD SOURCE="HED">ADDRESSES:</HD> The EPA has established a docket for this action under Docket ID No. EPA-R08-OAR-2020-0098. 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> Crystal Ostigaard, Air and Radiation Division, EPA, Region 8, Mailcode 8ARD-IO, 1595 Wynkoop Street, Denver, Colorado 80202-1129, telephone number: (303) 312-6602, email address: <E T="03">ostigaard.crystal@epa.gov.</E> </FURINF> <SUPLINF> <HD SOURCE="HED">SUPPLEMENTARY INFORMATION:</HD> Throughout this document “we,” “us,” and “our” means the EPA. <HD SOURCE="HD1">I. Background</HD> The background for this action is discussed in detail in our November 6, 2020 (85 FR 71023)  <SU>1</SU> <FTREF/> and July 16, 2025 (90 FR 31901) proposed actions. In the November 6, 2020, document we proposed to redesignate the Salt Lake City and Provo 2006 24-hour PM <E T="52">2.5</E> NAAs, and to approve multiple related SIP submissions. We proposed approval of the State's January 13, 2020 submittal to revise the SIP based upon revisions to R307-110-10, and the Provo and Salt Lake City 2006 24-hour PM <E T="52">2.5</E> maintenance plans and redesignation requests. We also proposed to approve both maintenance plans' 2035 motor vehicle emission budgets (budgets) and the levels of nitrogen oxide (NO <E T="52">X</E> ) and volatile organic compounds (VOC) to direct PM <E T="52">2.5</E> budgets trading mechanisms in each maintenance plan. Additionally, the EPA notified the public on October 7, 2025, through EPA's website that we proposed to find the 2035 budgets adequate for transportation conformity purposes. <SU>2</SU> <FTREF/> We proposed approval of these submissions because the Utah Division of Air Quality (UDAQ) adequately addressed all of the requirements of the Act for the SIP revisions and redesignations to attainment applicable to the Provo and Salt Lake City 2006 24-hour PM <E T="52">2.5</E> NAAs. We used the 2022-2024 ambient air quality data from the Provo and Salt Lake City NAAs as the basis for our final decision. Upon the effective date of this final action, the designation status of the Provo and Salt Lake City areas under 40 CFR part 81 will be revised to attainment. <FTNT> <SU>1</SU>  On April 6, 2021 (86 FR 17762) the comment period was reopened due to an administrative error where two documents were inadvertently left out of the record. </FTNT> <FTNT> <SU>2</SU>  Adequacy Review of State Implementation Plan (SIP) Submissions for Conformity, available at <E T="03">https://www.epa.gov/state-and-local-transportation/adequacy-review-state-implementation-plan-sip-submissions-conformity.</E> </FTNT> Additionally, we proposed to approve SIP revisions submitted on January 19, 2017 (Utah state SIP section IX.H.13) and February 15, 2019 (portions of Utah state SIP section IX.H.11 and 12). We also proposed to approve, through parallel processing, the removal of the startup/shutdown emission limits for the Kennecott Power Plant found in Utah state SIP section IX.H.12.i.i.C, which were formally submitted on October 9, 2020. The EPA proposed to approve the area sources, major stationary sources, on-road mobile sources, and non-road mobile sources BACM/BACT analyses for the Provo and Salt Lake City 2006 24-hour PM <E T="52">2.5</E> NAAs that were submitted on February 4, 2019 and February 15, 2019. Consistent with the EPA's procedures for parallel processing established under section 2.3 of appendix V to 40 CFR part 51, our July 16, 2025 (90 FR 31901) proposed approval relied upon our evaluation of the public draft version of the revisions to Utah state SIP sections IX.H.11 and 12, R307-110-17, and the revised BACM/BACT analyses for the five sources  <SU>3</SU> <FTREF/> that were adopted by the Utah Air Quality Board on May 7, 2025, and submitted to the EPA on May 20, 2025. UDAQ provided the final submittal to the EPA on July 15, 2025. We have reviewed this submittal and have determined that it does not differ from the public draft version submitted to the EPA on May 20, 2025, that was evaluated for our proposed approval. <FTNT> <SU>3</SU>  Big West, Chevron, Hexcel, HF Sinclair, and Marathon. </FTNT> <HD SOURCE="HD1">II. Response to Comments</HD> During the public notices and comment periods, we received multiple comments that were for and against both proposed actions. The full text of comments received are included in the publicly posted docket associated with this action at <E T="03">https://www.regulations.gov.</E> Our Response to Comments (RTC) document, which is also included in the docket, provides full, detailed responses to all significant comments received and further explains the basis for our final action. <HD SOURCE="HD1">III. Final Action</HD> We are approving the redesignation of the Salt Lake City and Provo 2006 24-hour PM <E T="52">2.5</E> NAAs, and the related SIP submissions because UDAQ has adequately addressed all of the requirements of the Act for the SIP revisions and the redesignation to attainment applicable to the Provo and Salt Lake City 2006 24-hour PM <E T="52">2.5</E> NAAs. <SU>4</SU> <FTREF/> <FTNT> <SU>4</SU>   <E T="03">See</E> design values within AQS reports found in the docket. </FTNT> We are approving the Governor of Utah's January 13, 2020 submittal, containing revisions to R307-110-10, and the Provo and Salt Lake City 2006 24-hour PM <E T="52">2.5</E> maintenance plans and redesignation requests. We are approving both maintenance plans' 2035 budgets. The final 2035 budgets for the Provo NAA are 1.5 tons per day (tpd) direct PM <E T="52">2.5</E> , 6.5 tpd NO <E T="52">X</E> , and 7.0 tpd VOCs and the final 2035 budgets for Salt Lake City NAA are 1.38 tpd direct PM <E T="52">2.5</E> , 21.63 tpd NO <E T="52">X</E> , and 20.57 tpd VOCs. We also find the budgets adequate, as they meet the adequacy criteria found in the transportation conformity regulation at 40 CFR 93.118(e)(4). The transportation conformity regulation at 40 CFR 93.118(f) sets forth the process by which the EPA reviews adequacy of transportation budgets. In addition, we are approving the NO <E T="52">X</E> and VOC levels to direct PM <E T="52">2.5</E> budgets trading mechanisms in each maintenance plan, as allowed for by the transportation conformity regulation at 40 CFR 93.124(b). Please see the November 6, 2020 proposed rule at 85 FR 71023 for additional information about the trading mechanism and its application in transportation conformity determinations in these areas. We are using 2022-2024 ambient air quality data from the Provo and Salt Lake City NAAs as the basis for our decision. Upon the effective date of this final action, the designation status of the Provo and Salt Lake City areas under 40 CFR part 81 will be revised to attainment. Additionally, we are approving SIP revisions submitted on January 19, 2017 (Utah state SIP section IX.H.13), and February 15, 2019 (portions of Utah state SIP section IX.H.11 and 12). We are approving the removal of the startup/shutdown emission limits for the Kennecott Power Plant found in Utah state SIP section IX.H.12.i.i.C, which was formally submitted by the State of Utah on December 14, 2020. The EPA is approving for incorporation into the SIP the area sour ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 27k characters. Full document text is stored and available for version comparison. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━