Final rule · 2025-18637

Air Plan Approval; California; San Joaquin Valley 1-Hour Ozone Area; Maintenance Plan and Redesignation Request

The Environmental Protection Agency (EPA) is taking final action to approve the "2023 Maintenance Plan and Redesignation Request for the Revoked 1-Hour Ozone Standard" ("San Joaquin Valley Maintenance Plan" or "Plan") as a revision to the state implementation plan (SIP) for the State of California. The San Joaquin Valley Maintenance Plan includes, among other elements, an emissions inventory consistent with attainment and contingency provisions. The EPA is also finalizing its finding that the State of California's request to redesignate the San Joaquin Valley area from nonattainment to attainment for the revoked 1979 1-hour national ambient air quality standard (NAAQS or "standard") for ozone ("1979 ozone NAAQS," "1-hour ozone NAAQS," or "1-hour ozone standard") meets all the Clean Air Act (CAA or "the Act") criteria for redesignation. Therefore, the EPA is terminating all anti-backsliding obligations for the San Joaquin Valley area for the revoked 1-hour ozone NAAQS.