Proposed rule · 2025-05369

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

The Environmental Protection Agency (EPA) is proposing 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 proposing to approve the revision under the Clean Air Act (CAA or "Act"). We are taking comments on this proposal and plan to follow with a final action.