Air Quality State Implementation Plans; Approvals and Promulgations: Michigan; Withdrawal of the Federal Implementation Plan for the Detroit Sulfur Dioxide Area

What it does

• •EPA proposes to withdraw the Federal Implementation Plan (FIP) for sulfur dioxide emissions in the Detroit area that was issued on October 12, 2022.
• •The withdrawal is proposed because Michigan submitted and EPA approved a revised State Implementation Plan (SIP) on May 19, 2025, making the federal plan redundant.
• •The revised Michigan SIP addresses attainment of the 2010 1-hour primary sulfur dioxide National Ambient Air Quality Standard for the Detroit nonattainment area.

Why it matters

• •Under the Clean Air Act, EPA must promulgate a federal implementation plan if a state fails to submit an adequate plan; withdrawal of a redundant FIP reflects resolution of the enforcement trigger and enables state rather than federal rule-making to govern air quality controls in the Detroit area.
• •The action removes overlapping federal and state regulatory requirements that would apply to industrial facilities in the Detroit area, including U.S. Steel, Cleveland-Cliffs Steel, and Dearborn Industrial Generation.

Who is affected

• •Michigan state government and industrial facilities in the Detroit area subject to SO₂ emission limits (U.S. Steel Corporation, EES Coke Battery, Cleveland-Cliffs Steel Corporation, Dearborn Industrial Generation, Carmeuse Lime, and DTE Trenton Channel).
• •Residents of the Detroit nonattainment area in Wayne County, Michigan.

What happens next

EPA is accepting public comments through December 28, 2026, and will hold a virtual public hearing on December 14, 2026, if hearing requests are submitted by November 27, 2026.