Finding of Failure To Attain the 1997 8-Hour Ozone Standards; California; San Joaquin Valley

<RULE> ENVIRONMENTAL PROTECTION AGENCY <CFR>40 CFR Part 52</CFR> <DEPDOC>[EPA-R09-OAR-2024-0587; FRL-12483-02-R9]</DEPDOC> <SUBJECT>Finding of Failure To Attain the 1997 8-Hour Ozone Standards; California; San Joaquin Valley</SUBJECT> <HD SOURCE="HED">AGENCY:</HD> Environmental Protection Agency (EPA). <HD SOURCE="HED">ACTION:</HD> Final determination. <SUM> <HD SOURCE="HED">SUMMARY:</HD> The Environmental Protection Agency (EPA) has determined that the San Joaquin Valley, California area failed to attain the 1997 8-hour ozone national ambient air quality standard (NAAQS) by its June 15, 2024 “Extreme” area attainment date. This determination is based on quality-assured and certified ambient air quality monitoring data from 2021 through 2023. As a result of this determination, the State of California is required to implement nonattainment contingency measures and the stationary source fee program required under Clean Air Act (CAA) section 185. </SUM> <EFFDATE> <HD SOURCE="HED">DATES:</HD> This determination is effective on October 27, 2025. </EFFDATE> <HD SOURCE="HED">ADDRESSES:</HD> The EPA has established a docket for this action under Docket ID No. EPA-R09-OAR-2024-0587. 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. 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 <E T="02">FOR FURTHER INFORMATION CONTACT</E> section. <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> Laura Lawrence, EPA Region IX, 75 Hawthorne St., San Francisco, CA 94105: phone: (415) 972-3407; email: <E T="03">lawrence.laura@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. Background</FP> <FP SOURCE="FP-2">II. Public Comments and EPA Responses</FP> <FP SOURCE="FP-2">III. EPA Action</FP> <FP SOURCE="FP-2">IV. Statutory and Executive Order Reviews</FP> </EXTRACT> <HD SOURCE="HD1">I. Background</HD> On July 10, 2025, the EPA proposed to determine that the San Joaquin Valley area failed to attain the 1997 8-hour ozone NAAQS by its applicable attainment date. <SU>1</SU> <FTREF/> Our proposed determination was based on three years of quality-assured and certified ambient air quality monitoring data for the 2021 to 2023 monitoring period. <SU>2</SU> <FTREF/> <FTNT> <SU>1</SU>  90 FR 30607. </FTNT> <FTNT> <SU>2</SU>  An area is considered to have attained the 1997 8-hour ozone standard if there are no violations of the standard, as determined in accordance with 40 CFR 50.10, based on three consecutive years of complete, quality-assured, and certified monitoring data. A violation occurs when the ambient ozone air quality monitoring data show that the 3-year average of the annual fourth highest daily maximum 8-hour average ozone concentrations at an ozone monitor is greater than 0.08 ppm. Due to rounding and truncation conventions, the computed 3-year average ozone concentration of 0.085 ppm is the smallest value that is greater than 0.08 ppm. </FTNT> In 1997, the EPA revised the NAAQS for ozone to set the acceptable level of ozone in the ambient air at 0.08 ppm, averaged over an 8-hour period. <SU>3</SU> <FTREF/> The EPA tightened the 8-hour ozone NAAQS in 2008 and tightened the 8-hour ozone NAAQS further in 2015, but this determination applies only to the 1997 8-hour ozone NAAQS. <SU>4</SU> <FTREF/> The EPA revoked the 1997 8-hour ozone NAAQS effective April 6, 2015;  <SU>5</SU> <FTREF/> however, to comply with anti-backsliding requirements of the Act, areas designated nonattainment at the time that the 1997 8-hour ozone NAAQS was revoked remain subject to certain requirements based on their classification at the time of revocation, including requirements related to nonattainment contingency measures under CAA sections 172(c)(9) and 182(c)(9) and, for “Severe” and “Extreme” areas, major source fee programs under CAA section 185. <SU>6</SU> <FTREF/> The EPA's determination that an area failed to attain by its attainment date, which is made under CAA section 301 and consistent with section 181(b)(2), triggers these anti-backsliding requirements. <E T="03">See South Coast Air Quality Mgmt. Dist.</E> v. <E T="03">EPA,</E> 882 F.3d 1138, 1147 (D.C. Cir. 2018) (“ <E T="03">South Coast II”</E> ). <FTNT> <SU>3</SU>  62 FR 38856 (July 18, 1997). We refer to the ozone NAAQS established by the EPA in 1997 as the “1997 8-hour ozone NAAQS” or “1997 8-hour ozone standard.” </FTNT> <FTNT> <SU>4</SU>  73 FR 16436 (March 27, 2008) (referred to as the “2008 ozone NAAQS”). The EPA further tightened the 8-hour ozone NAAQS at 80 FR 65292 (October 26, 2015) (referred to as the “2015 ozone NAAQS”). </FTNT> <FTNT> <SU>5</SU>  80 FR 12264 (March 6, 2015). </FTNT> <FTNT> <SU>6</SU>  40 CFR 51.1100(o). </FTNT> The area designated as the San Joaquin Valley area consists of San Joaquin, Stanislaus, Merced, Madera, Fresno, Tulare, and Kings counties, and the western portion of Kern County. The area stretches over 250 miles from north to south, averages a width of 80 miles, and encompasses over 23,000 square miles. It is partially enclosed by the Coast Mountain range to the west, the Tehachapi Mountains to the south, and the Sierra Nevada range to the east. <SU>7</SU> <FTREF/> The population of the San Joaquin Valley area is over 4.3 million people. <SU>8</SU> <FTREF/> <FTNT> <SU>7</SU>  For a precise definition of the boundaries of the San Joaquin Valley area for the 1997 8-hour ozone NAAQS, see 40 CFR 81.305. </FTNT> <FTNT> <SU>8</SU>  SJVUAPCD, <E T="03">2022 Plan for the 2015 8-Hour Ozone Standard (December 15, 2022),</E> p. 2-7. </FTNT> The San Joaquin Valley area, excluding areas of Indian country, <SU>9</SU> <FTREF/> lies within the jurisdiction of the San Joaquin Valley Unified Air Pollution Control District (SJVUAPCD or “District”). Under California law, SJVUAPCD is responsible for adopting and implementing stationary source rules in the San Joaquin Valley, such as the fee program rules required under CAA section 185, while the California Air Resources Board (CARB) adopts and implements consumer products and mobile source rules subject to the requirements of CAA section 209. CARB submits District and State rules to the EPA for approval into the state implementation plan (SIP). <FTNT> <SU>9</SU>  “Indian country” as defined at 18 U.S.C. 1151 refers to: “(a) all land within the limits of any Indian reservation under the jurisdiction of the United States Government, notwithstanding the issuance of any patent, and, including rights-of-way running through the reservation, (b) all dependent Indian communities within the borders of the United States whether within the original or subsequently acquired territory thereof, and whether within or without the limits of a state, and (c) all Indian allotments, the Indian titles to which have not been extinguished, including rights-of-way running through the same.” </FTNT> Our proposed determination provides additional background information on the effects of exposure to elevated levels of ground level ozone, the designation and classification of the San Joaquin Valley under the CAA for the 1997 ozone NAAQS, and the statutory and regulatory provisions that apply to determinations of attainment. It also describes our review of the air quality monitoring data on which we based our proposed determination that the area failed to attain the 1997 ozone NAAQS by the applicable attainment date. <HD SOURCE="HD1">II. Public Comments and EPA Responses</HD> Our July 10, 2025 proposed determination provided a 30-day public comment period that closed on August 11, 2025. During this period, we received three comment letters. The comment letters are included in the docket for this action. Our summary of the comments and our responses are as follows: <E T="03">Comment 1:</E> An anonymous commenter asserts that the EPA's proposed determination underscores the chronic difficulty in controlling ozone precursors in a region with high population vulnerability, intense industrial and agricultural activity, and significant climate exposure. The commenter observes that warming temperatures driven by elevated carbon dioxide (CO <E T="52">2</E> ) accelerate photochemical reactions, lengthen the ozone season, and reduce the effectiveness of existing controls. The commenter urges the EPA to recognize the amplifying role of CO <E T="52">2</E> -driven climate effects on ozone nonattainment, particularly in climate-sensitive regions like California's Central Valley; to encourage California and local air districts to integrate greenhouse gas (GHG) mitigation strategies into ozone planning; and to promote transparency in SIP updates and future planning by requiring or recommending that CO <E T="52">2</E> co-emissions from major sources be disclosed and evaluated. <E T="03">Response 1:</E> The EPA acknowledges the points made by the commenter, but notes that none of the statements or arguments ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 21k characters. 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