Approval and Promulgation of Implementation Plans and Designation of Areas for Air Quality Planning Purposes; Michigan; Redesignation of the Detroit-Ann Arbor Area to Attainment for Ozone

EPA is making a determination under the Clean Air Act (CAA) that the Detroit-Ann Arbor nonattainment area has attained the 8-hour ozone National Ambient Air Quality Standard (NAAQS). The Detroit-Ann Arbor area includes Lenawee, Livingston, Macomb, Monroe, Oakland, St. Clair, Washtenaw, and Wayne Counties. This determination is based on quality-assured ambient air quality monitoring data for the 2006-2008 ozone seasons that demonstrate that the 8-hour ozone NAAQS has been attained in the area. EPA is approving a request from the State of Michigan to redesignate the Detroit-Ann Arbor area to attainment of the 8-hour ozone NAAQS. The Michigan Department of Environmental Quality (MDEQ) submitted this request on March 6, 2009. In approving this request, EPA is also approving, as a revision to the Michigan State Implementation Plan (SIP), the State's plan for maintaining the 8-hour ozone NAAQS in the area through 2020. EPA is approving the 2005 base year emissions inventory for the Detroit-Ann Arbor area as meeting the requirements of section 182(a)(1) of the CAA. EPA also finds adequate and is approving the State's 2020 Motor Vehicle Emission Budgets (MVEBs) for the Detroit-Ann Arbor area. EPA proposed these actions on April 23, 2009. EPA provided a 30-day review and comment period, which closed on May 26, 2009. EPA received comments in support of the redesignation from Consumers Energy and the Southeast Michigan Council of Governments. EPA received no comments in opposition to the proposal.