Air Plan Approval; Michigan; Redesignation of the Berrien, MI and Muskegon, MI Areas to Attainment of the 2015 Ozone Standards

The Environmental Protection Agency (EPA) is proposing to approve the Michigan Department of Environment, Great Lakes, and Energy's (EGLE's) December 26, 2025, requests to redesignate the Berrien and Muskegon areas to attainment for the 2015 ozone NAAQS because the requests meet the statutory requirements for redesignation under the Clean Air Act (CAA). The Berrien area includes Berrien County, and the Muskegon area includes the western portion of Muskegon County. The EPA is proposing to approve, as revisions to the Michigan State Implementation Plan (SIP), the State's plans for maintaining the 2015 ozone NAAQS through 2036 in the Berrien and Muskegon areas. The EPA is initiating the adequacy process and proposing to approve Michigan's 2032 and 2036 volatile organic compound (VOC) and oxides of nitrogen (NO<INF>X</INF>) motor vehicle emissions budgets (budgets) for the Berrien and Muskegon areas. Pursuant to section 110 and part D of the CAA, the EPA is proposing to approve the enhanced monitoring plan (EMP) of ozone and ozone precursors SIP revision submitted by Michigan on January 12, 2026, because it satisfies Serious SIP requirements of the CAA for the Berrien and Muskegon areas. The EPA is also proposing to approve the Serious VOC reasonably available control technology (RACT) SIP revision and CAA section 182(f) waiver from Serious NO<INF>X</INF> RACT requirements for the Berrien and Muskegon areas under the 2015 ozone NAAQS submitted by EGLE to the EPA on May 5, 2026.