EPA is approving the State Implementation Plan (SIP) revision submitted by the State of Wyoming on September 12, 2003. The revision restructures the Wyoming Air Quality Standards and Regulations (WAQS&R) from a single chapter into thirteen separate chapters and renumbers the provisions within each chapter. The submitted revision contains no substantive changes to the existing SIP-approved regulations. The intended effect of this action is to make federally enforceable the restructured WAQS&R. This action is being taken under section 110 of the Clean Air Act.