Determination of Attainment by the Attainment Date; California; Mariposa County; 2015 8-Hour Ozone National Ambient Air Quality Standards

<RULE> ENVIRONMENTAL PROTECTION AGENCY <CFR>40 CFR Part 52</CFR> <DEPDOC>[EPA-R09-OAR-2025-0084; FRL-12611-02-R9]</DEPDOC> <SUBJECT>Determination of Attainment by the Attainment Date; California; Mariposa County; 2015 8-Hour 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 taking final action to determine that the Mariposa County nonattainment area in California (“Mariposa area”) attained the 2015 ozone national ambient air quality standards (NAAQS or “standard”) by its August 3, 2024 attainment date. Our determination of attainment is based on complete, quality-assured, and certified ambient air quality monitoring data for calendar years 2021-2023, excluding data that showed exceedances due to exceptional events that occurred in 2021 and 2022. As a result of this action, Clean Air Act (CAA or “Act”) section 172(c)(9) contingency measures for failure to attain the 2015 ozone NAAQS and contingency measures for failure to make reasonable further progress (RFP) are no longer required for this standard in the Mariposa area. This action fulfills the EPA's statutory obligation to determine whether the Mariposa area attained the NAAQS by the attainment date. </SUM> <EFFDATE> <HD SOURCE="HED">DATES:</HD> This rule is effective on December 1, 2025. </EFFDATE> <HD SOURCE="HED">ADDRESSES:</HD> The EPA has established a docket for this action under Docket ID No. EPA-R09-OAR-2025-0084. All documents in the docket are listed at <E T="03">https://www.regulations.gov.</E> 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. If you need assistance in a language other than English or if you are a person with disabilities who needs a reasonable accommodation at no cost to you, please contact the person identified in the <E T="02">FOR FURTHER INFORMATION CONTACT</E> section. <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> Roxana Sierra-Hernández, Air Planning Section, Planning & Analysis Branch, Air & Radiation Division, EPA Region IX, 75 Hawthorne Street, San Francisco, CA 94105. By phone at (213) 244-1891, or by email at <E T="03">SierraHernandez.Roxana@epa.gov.</E> </FURINF> <SUPLINF> <HD SOURCE="HED">SUPPLEMENTARY INFORMATION:</HD> Throughout this document, “we,” “us,” and “our” refer to the EPA. <HD SOURCE="HD1">Table of Contents</HD> <EXTRACT> <FP SOURCE="FP-2">I. Summary of the Proposed Action</FP> <FP SOURCE="FP-2">II. Public Comments and EPA Responses</FP> <FP SOURCE="FP-2">III. Final Determination</FP> <FP SOURCE="FP-2">IV. Statutory and Executive Order Reviews</FP> </EXTRACT> <HD SOURCE="HD1">I. Summary of the Proposed Action</HD> On June 3, 2025, <SU>1</SU> <FTREF/> the EPA proposed to determine that the Mariposa area, classified as “Moderate” for the 2015 ozone NAAQS, attained the 2015 ozone NAAQS by the August 3, 2024 attainment date. The EPA proposed this determination to fulfill our statutory obligation under CAA section 181(b)(2) to determine whether the area attained the 2015 ozone NAAQS by its attainment date. Our proposed determination was based on complete, quality-assured, and certified ambient air quality monitoring data. <FTNT> <SU>1</SU>  90 FR 23501 (June 3, 2025). </FTNT> In our proposed rulemaking, we provided background information on the 2015 ozone standard and the Mariposa area designation for it. In section II of our proposed determination, we explained that an area attains the 2015 ozone NAAQS when its design value ( <E T="03">i.e.,</E> the 3-year average of the annual fourth highest daily maximum 8-hour average ambient air quality ozone concentration) does not exceed 0.070 parts per million (ppm). In our proposed rulemaking, we analyzed the ozone monitoring data submitted to EPA's Air Quality System (AQS) database for calendar years 2021, 2022, and 2023. Ozone exceedances caused by uncontrollable wildfire emissions in 2021 and 2022 were excluded from our evaluation of whether the Mariposa area attained the 2015 ozone NAAQS by the attainment date. A summary of the resulting ozone design values for the two ozone monitoring sites in the Mariposa area are shown in Table 1. <GPOTABLE COLS="6" OPTS="L2,nj,i1" CDEF="xs72,r50,12,12,12,12"> <TTITLE> Table 1—2015 Ozone NAAQS Monitoring Data Summary for the Mariposa Area  <E T="01"> <SU>a</SU> </E> </TTITLE> <CHED H="1">AQS site ID</CHED> <CHED H="1">Monitoring site name</CHED> <CHED H="1">4th Highest daily maximum 8-hour average value (ppm)</CHED> <CHED H="2">2021</CHED> <CHED H="2">2022</CHED> <CHED H="2">2023</CHED> <ENT>0.077</ENT> <ENT>0.067</ENT> <ENT>0.068</ENT> <ENT>0.070</ENT> </ROW> <ROW> <ENT I="01">06-043-0006</ENT> <ENT>Jerseydale</ENT> <ENT>0.081</ENT> <ENT>0.070</ENT> <ENT>0.060</ENT> <ENT>0.070</ENT> </ROW> <TNOTE> <SU>a</SU>  The data shown exclude exceedances due to exceptional events. </TNOTE> <TNOTE> Source: EPA, AQS Design Value (AMP 480), Report Request ID: 2265346, February 24, 2025.</TNOTE> </GPOTABLE> We also proposed to determine that, if this action is finalized, the CAA section 172(c)(9) requirement for states to provide contingency measures in the event the area fails to attain the NAAQS or fails to achieve RFP would no longer apply for the 2015 ozone standard for the Mariposa area. <HD SOURCE="HD1">II. Public Comments and EPA Responses</HD> The EPA's proposed action provided a 30-day public comment period that ended on July 3, 2025. During this period, no comments were received. <HD SOURCE="HD1">III. Final Determination</HD> Pursuant to section 181(b)(2)(A) of the CAA, the EPA is making a final determination that the Mariposa area attained the 2015 ozone NAAQS by the attainment date of August 3, 2024. Once effective, this final action satisfies the EPA's obligation to determine, based on an area's air quality as of the attainment date, whether the Mariposa area attained the 2015 ozone standard by its applicable attainment date. We are also making a final determination that the CAA requirement for the state implementation plan to provide for attainment and RFP contingency measures will no longer apply to the Mariposa area for the 2015 ozone NAAQS. The Mariposa area will not be redesignated and will continue to comply with applicable requirements for a Moderate ozone nonattainment area. <HD SOURCE="HD1">IV. Statutory and Executive Order Reviews</HD> <HD SOURCE="HD2">A. Executive Order 12866: Regulatory Planning and Review and Executive Order 13563: Improving Regulation and Regulatory Review</HD> This action is not a significant regulatory action and was therefore not submitted to the Office of Management and Budget (OMB) for review. <HD SOURCE="HD2">B. Executive Order 14192: Unleashing Prosperity Through Deregulation</HD> Executive Order 14192 does not apply because actions that make attainment determinations under Clean Air Act section 181(b)(2) are exempted from review under Executive Order 12866. <HD SOURCE="HD2">C. Paperwork Reduction Act (PRA)</HD> 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. <HD SOURCE="HD2">D. Regulatory Flexibility Act (RFA)</HD> 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. <HD SOURCE="HD2">E. Unfunded Mandates Reform Act (UMRA)</HD> 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. <HD SOURCE="HD2">F. Executive Order 13132: Federalism</HD> 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. <HD SOURCE="HD2">G. Executive Order 13175: Coordination With Indian Tribal Governments</HD> This action does not have tribal implications, as specified in Executive Order 13175, because the action 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. <HD SOURCE="HD2">H. Executive Order 13045: Protection of Children From Environmental Health Risks and Safety Risks</HD> 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. This action is not subject to Executive Order 13045 because it does not concern an environmental health risk or ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 13k characters. Full document text is stored and available for version comparison. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━