Final rule · 2025-17061

Air Plan Approval; California; State Implementation Plan Revision for Chico, Modesto and Stockton Carbon Monoxide Maintenance Areas

The Environmental Protection Agency (EPA) is taking final action to approve a revision to the California state implementation plan (SIP) that removes carbon monoxide (CO) contingency measures and monitoring requirements from the maintenance plan for three CO maintenance areas: Chico Urbanized Area, Modesto Urbanized Area, and Stockton Urbanized Area. We are approving the revision under the Clean Air Act (CAA or "Act").