# Finding of Failure To Attain the 1997 8-Hour Ozone Standards; California; San Joaquin Valley
> **Rule** · Final determination. · Published 2025-09-25 · Effective 2025-10-27 · 90 FR 46065
## Document
- **Document number:** 2025-18636
- **Category:** air-emissions
- **Federal Register citation:** 90 FR 46065
- **CFR reference:** 40 CFR 52
- **Publication date:** 2025-09-25
- **Effective date:** 2025-10-27
- **State:** CA
- **EPA docket:** EPA-R09-OAR-2024-0587
## Abstract

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.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2025/09/25/2025-18636/finding-of-failure-to-attain-the-1997-8-hour-ozone-standards-california-san-joaquin-valley)
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