The Environmental Protection Agency (EPA) is determining that the Denver-Boulder-Greeley-Ft. Collins-Loveland, Colorado nonattainment area (Denver Area) failed to attain the 2008 ozone National Ambient Air Quality Standard (NAAQS) by the applicable attainment date for "Moderate" nonattainment areas. The effect of failing to attain by the attainment date is that the area will be reclassified by operation of law to "Serious" upon the effective date of this final reclassification action. Along with the reclassification, the EPA is finalizing deadlines for submittal of SIP revisions required under the new classification and implementation of related control requirements. This final action is necessary to fulfill the EPA's statutory obligation to determine whether the Denver Area attained the NAAQS by the attainment date, and, within six months of the attainment date, to publish a document in the Federal Register identifying each area that is determined as having failed to attain and its reclassification.