Clean Air Act Approval and Promulgation of State Implementation Plan for Colorado; Carbon Monoxide Attainment Demonstrations and Related SIP Elements for Denver and Longmont; Clean Air Act Reclassification; Oxygenated Gasoline Program

In this document, EPA is approving the State Implementation Plan (SIP) revisions submitted by the State of Colorado for the purpose of bringing about the attainment of the national ambient air quality standards (NAAQS) for carbon monoxide (CO). The implementation plan revisions were submitted by the State on July 11 and 13, 1994, September 29, 1995, and December 22, 1995 to satisfy certain Federal requirements for an approvable nonattainment area CO SIP for Denver and Longmont. This action includes approval of revisions to Colorado Regulations 11 (vehicle inspection and maintenance (I/M)) and 13 (oxygenated fuels) submitted to satisfy conditions in the SIP, and further revisions to Regulation 13 to shorten the effective period of the oxygenated fuels program. It also includes reclassification of the Denver CO nonattainment area from Moderate to Serious. EPA proposed to approve the July 1994 and September 1995 SIP submissions and to reclassify the Denver area to Serious in the Federal Register on July 9, 1996. EPA published a supplemental proposal to approve the December 22, 1995 SIP submission shortening the oxygenated fuels program period and to approve the Denver and Longmont CO SIPs based on the shortened period on December 6, 1996. The rationale for the final approvals and reclassification are set forth in this document. Additional information is available at the address indicated below.