Air Plan Approval; ID; Regional Haze Plan for the Second Implementation Period

The Environmental Protection Agency (EPA) is approving the Idaho regional haze State Implementation Plan (SIP) revision submitted on August 5, 2022, supplemented on September 27, 2024, and clarified on August 12, 2025, as satisfying applicable requirements under the Clean Air Act and the EPA's Regional Haze Rule (RHR) for the program's second implementation period. The Idaho SIP revision addressed the requirement to make reasonable progress toward the national goal of preventing any future, and remedying any existing, anthropogenic impairment of visibility in certain national parks and wilderness areas.