Air Plan Approval; Michigan; Redesignation and Maintenance Plan for the Partial St. Clair 2010 1-Hour Sulfur Dioxide (SO2) NAAQS Nonattainment Area

The Environmental Protection Agency (EPA) is proposing to redesignate the St. Clair nonattainment area in southeast Michigan to attainment for the 2010 sulfur dioxide (SO<INF>2</INF>) National Ambient Air Quality Standard (NAAQS). The EPA is also proposing to approve Michigan's maintenance plan for the St. Clair SO<INF>2</INF> nonattainment area and emissions limits for the DTE Belle River Power Plant. Michigan submitted the request for approval of the St. Clair area redesignation and maintenance plan on December 15, 2023, with a supplement to the request on July 24, 2025.