The Environmental Protection Agency (EPA) is approving changes to the Tennessee State Implementation Plan (SIP) to revise New Source Review (NSR) regulations. Specifically, EPA is approving the portions of a SIP revision submitted by the State of Tennessee, through the Tennessee Department of Environment and Conservation (TDEC), on May 28, 2009, that modify the definitions of "baseline actual emissions." This action is being taken pursuant to the Clean Air Act (CAA or Act).