The Environmental Protection Agency (EPA) is taking final action to approve revisions to the Arizona Department of Environmental Quality (ADEQ) and Maricopa County Air Quality Department (MCAQD) portions of the Arizona State Implementation Plan (SIP). These revisions were submitted by ADEQ and MCAQD in response to the EPA's June 12, 2015 finding of substantial inadequacy and SIP call for certain provisions in the SIP related to excess emissions during startup, shutdown, and malfunction (SSM) events. The EPA is finalizing approval of the SIP revisions because the Agency has determined that they are in accordance with the requirements for SIP provisions under the Clean Air Act (CAA or the Act) and correct deficiencies identified in the June 12, 2015 SIP call.