EPA is finalizing the approval of revisions to the Nevada State Implementation Plan (SIP) proposed in the Federal Register on December 11, 1998. This action specifically includes approval of revisions to Clark County Health District's wintertime oxygenated fuels program. This approval action will incorporate these revisions into the federally approved SIP. The intended effect of approving these revisions is to regulate emissions of carbon monoxides (CO) in accordance with the requirements of the Clean Air Act, as amended in 1990 (CAA or the Act). Thus, EPA is finalizing the approval of these revisions into the Nevada SIP under provisions of the CAA regarding EPA action on SIP submittals, SIPs for national primary and secondary ambient air quality standards and plan requirements for nonattainment areas.