The Environmental Protection Agency (EPA) is approving, under the Clean Air Act (CAA), a request submitted by the Michigan Department of Environment, Great Lakes, and Energy (EGLE) on December 18, 2020, to revise the Michigan State Implementation Plan (SIP). EGLE's submittal addresses the emissions inventory and statement requirements for the Allegan County, Berrien County, Detroit (Livingston, Macomb, Monroe, Oakland, St. Clair, Washtenaw, and Wayne Counties) and Muskegon County nonattainment areas under the 2015 ozone National Ambient Air Quality Standard (NAAQS or standard). The CAA requires states to develop and submit, as SIP revisions, emission inventories for all ozone nonattainment areas. In this action, EPA is approving EGLE's emissions inventories for the Allegan County, Berrien County, and Muskegon County nonattainment areas under the 2015 ozone NAAQS and the removal of the repealed Act 348, Section 14a. EPA approved the portions of EGLE's December 18, 2020, submittal pertaining to the certification of EGLE's stationary annual emissions statement regulation and emissions inventories for the Detroit nonattainment area under the 2015 ozone NAAQS in a separate action on July 6, 2022.