The U.S. Environmental Protection Agency (EPA) is taking direct final action to approve a State Implementation Plan (SIP) revision submitted by the State of Tennessee, through the Tennessee Department of Environment and Conservation (TDEC), on March 25, 1999. The SIP submittal includes a change to the TDEC regulation "Reasonable Measures Required." EPA is proposing to approve this SIP revision because it is consistent with the Clean Air Act (CAA or Act) and federal regulations governing SIPs.