The Environmental Protection Agency (EPA) is approving a State Implementation Plan (SIP) revision submitted by the Montana Department of Environmental Quality (MDEQ or "the State"), on January 30, 2024, requesting to change the status of gasoline requirements (the "oxygenated fuels" or "oxyfuels" program) in the Missoula, Montana Carbon Monoxide (CO) Limited Maintenance Plan (LMP) from active control measure to a contingency measure. The SIP revision contains a non- interference demonstration under the Clean Air Act (CAA), which concludes that converting the oxygenated gasoline program from a control measure to a contingency measure in the Missoula CO LMP would not interfere with attainment or maintenance of the CO National Ambient Air Quality Standard (NAAQS). The EPA is finalizing approval of Montana's SIP submittal pursuant the CAA.