The EPA is granting conditional interim approval of a State Implementation Plan (SIP) revision submitted by Texas. This revision establishes and requires the implementation of an enhanced inspection and maintenance (I/M) program in the Houston/Galveston and El Paso areas and a basic I/M program in the Dallas/Fort Worth area. The effect of this action is to conditionally approve Texas's I/M program for an interim period to last 18 months, based upon the good faith estimate of the program's performance. This action is being taken under section 110 of the Clean Air Act (Act) and section 348 of the National Highway Systems Designation Act (NHSDA).