On April 2, 2013, EPA published approval of revisions to the Texas State Implementation Plan ("SIP") for the Houston/Galveston/Brazoria ("HGB") 1997 8-hour ozone nonattainment area (78 Fed. Reg. 19599). The action finalizes EPA’s proposed approval of portions of two SIP revisions Texas submitted as meeting certain Reasonably Available Control Technology requirements for volatile organic compounds and oxides of nitrogen in the HGB area. EPA also finalized its proposal to approve the 2007 Voluntary Mobile Emission Reduction Program commitments for the HGB Area. The revisions will be effective on May 2, 2013.

On April 23, 2013, the Texas Commission on Environmental Quality ("TCEQ") adopted two revisions to the Texas SIP. The Infrastructure and Transport SIP Revision for the 2010 Sulfur Dioxide ("SO₂") National Ambient Air Quality Standard ("NAAQS") identifies basic program elements enabling Texas to meet NAAQS infrastructure requirements, and includes a technical demonstration that Texas neither contributes significantly to nonattainment nor interferes with maintenance of the SO₂ NAAQS in any other state. The HGB 1997 Eight-Hour Ozone Standard Nonattainment Area Motor Vehicle Emissions Budgets ("MVEB") Update SIP Revision will replace MVEBs for the HGB area with MVEBs created using the EPA’s latest mobile emissions estimation model, and will address outstanding contingency obligations for the HGB area and Clean Air Act requirements for transportation control measures in severe nonattainment areas.