Final rule · 2026-00003

Extension of the State Implementation Plan Due Date for the Regional Haze Third Implementation Period

The Environmental Protection Agency (EPA) is finalizing revisions to the Regional Haze Rule (RHR) under the Clean Air Act (CAA) to change the due date for the next round of State Implementation Plans (SIPs) for the third implementation period from July 31, 2028, to July 31, 2031. Under the RHR, States must submit plans to protect visibility in mandatory Class I Federal areas to make reasonable progress towards the national goal of preventing any future, and remedying any existing, impairment of visibility in Class I areas.