Final rule · 2025-00220

Revisions to the Federal Implementation Plan for the Billings/Laurel, Montana, Sulfur Dioxide Area

The Environmental Protection Agency (EPA) is revising a Federal Implementation Plan (FIP) applicable to sulfur dioxide (SO<INF>2</INF>) emissions from four sources located in Billings and Laurel, Montana. Specifically, the EPA is revising a portion of the FIP promulgated by the EPA in 2008 (2008 Billings/Laurel SO<INF>2</INF> FIP) by removing a provision which contained an affirmative defense for exceedances of flare emission limits during malfunctions, startups, and shutdowns. The EPA is taking this action pursuant to the Clean Air Act (CAA).