Air Plan Approval; Michigan; Redesignation and Maintenance Plan for the Partial St. Clair 2010 1-Hour Sulfur Dioxide (SO2) NAAQS Nonattainment Area
Key claim: EPA finalizes redesignation of the St. Clair, Michigan SO2 nonattainment area to attainment for the 2010 1-hour SO2 NAAQS and approves Michigan’s maintenance plan including emissions limits for the DTE Belle River Power Plant.
Abstract
(Rule · Environmental Protection Agency) The Environmental Protection Agency (EPA) is taking final action to redesignate the St. Clair nonattainment area in southeast Michigan to attainment for the 2010 sulfur dioxide (SO2) National Ambient Air Quality Standard (NAAQS). The EPA is also approving Michigan’s maintenance plan for the St. Clair SO2 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 14, 2023, with a supplement to the request on July 24, 2025. The EPA proposed to approve this action on April 10, 2026, and received no adverse comments.
Why this matters
Redesignations to attainment paired with source-specific maintenance limits show how localized nonattainment problems get resolved through enforceable SIP limits on individual large emitters — here, a coal-fired EGU. The practical effect is to lock in existing SO2 controls at Belle River as federally enforceable while relieving the area of nonattainment-area permitting burdens, a template that recurs across SO2 and ozone maintenance plans.