The Environmental Protection Agency (EPA) is approving portions of a State Implementation Plan (SIP) revision submitted by the State of Tennessee, through the Tennessee Department of Environment and Conservation (TDEC), on November 19, 2016, as supplemented on January 20, 2023, in response to a finding of substantial inadequacy and SIP call published on June 12, 2015, regarding provisions in the Tennessee SIP related to excess emissions during startup, shutdown, and malfunction (SSM) events. Tennessee's January 20, 2023, supplemental SIP revision includes some additional changes related to the 2015 SIP call, plus other changes unrelated to the SIP call, in the affected chapter of Tennessee's regulations.