Pursuant to the Federal Clean Air Act (CAA, the Act), the Environmental Protection Agency (EPA) is disapproving a revision to the Texas State Implementation Plan (SIP) submitted by the State of Texas through the Texas Commission on Environmental Quality (TCEQ) on August 20, 2020 (2020 SIP revision). The 2020 SIP revision addresses emissions during planned Maintenance, Startup and Shutdown (MSS) activities for certain Electric Generating Units (EGUs) and includes requirements intended to address visible emissions (opacity) and Particulate Matter (PM) emissions during planned MSS activities. The requirements are included in eight Agreed Orders (AOs) issued by TCEQ to the affected EGUs and provided in the 2020 SIP revision. EPA determined that the requirements contained in these AOs do not meet the CAA enforceability requirements or the CAA requirement that emission limitations must apply on a continuous basis. We are taking this action in accordance with section 110 of the Act.