Air Plan Approval; Michigan; Clean Data Determination for the Berrien, MI and Muskegon, MI Areas for the 2015 Ozone Standards

The Environmental Protection Agency (EPA) is proposing to determine under the Clean Air Act (CAA) that the Berrien, Michigan and Muskegon, Michigan areas have attained the 2015 ozone National Ambient Air Quality Standards (NAAQS or standards). This determination, often referred to as a clean data determination, is based upon complete, quality-assured, and certified ambient air monitoring data for the 2023-2025 design value period showing that the areas achieved attainment of the 2015 ozone NAAQS. This clean data determination also relies upon the Michigan Department of Environment, Great Lakes, and Energy's (EGLE's) exceptional events requests submitted to the EPA on December 26, 2025, and concurred upon by the EPA on January 12, 2026. As a result of this determination, the EPA is proposing to suspend the requirements for the Berrien and Muskegon areas to submit attainment demonstrations and associated Reasonably Available Control Measures (RACM), Reasonable Further Progress (RFP) plans, contingency measures for failure to attain or make reasonable progress, and other planning State Implementation Plans (SIPs) related to attainment of the 2015 ozone NAAQS, for as long as the areas continue to attain the 2015 ozone NAAQS.