In this document EPA is making a final finding that the Clark County, Nevada carbon monoxide (CO) nonattainment area has not attained the CO national ambient air quality standard (NAAQS) under the Clean Air Act (CAA) after having received a one year extension from the mandated attainment date of December 31, 1995 for moderate nonattainment areas to December 31, 1996. This finding is based on EPA's review of monitored air quality data for compliance with the CO NAAQS. As a result of this finding, the Clark County, Nevada nonattainment area is reclassified as a serious CO nonattainment area by operation of law. The intended effect of the reclassification is to allow the State 18 months from the effective date of this action to submit a new State Implementation Plan (SIP) demonstrating attainment of the CO NAAQS as expeditiously as practical but no later than December 31, 2000, the CAA attainment date for serious areas.