Pursuant to the Federal Clean Air Act (CAA or the Act), the Environmental Protection Agency (EPA) is disapproving revisions to the Texas State Implementation Plan (SIP) for the Dallas-Fort Worth (DFW) and Houston-Galveston-Brazoria (HGB) Serious ozone nonattainment areas for the 2008 ozone National Ambient Air Quality Standard (NAAQS). Specifically, EPA is disapproving the portion of these SIP revisions that the state intended to address contingency measure requirements. Contingency measures are control requirements in a nonattainment area SIP that would take effect should the area fail to meet Reasonable Further Progress (RFP) emissions reductions requirements or fail to attain the NAAQS by the applicable attainment date.