This rule finalizes EPA's finding of nonattainment and reclassification of the Imperial County 8-hour ozone nonattainment area (Imperial County). EPA finds that Imperial County has failed to attain the 8-hour ozone national ambient air quality standard ("NAAQS" or "standard") by June 15, 2007, the attainment deadline set forth in the Clean Air Act (CAA) and Code of Federal Regulations (CFR) for marginal nonattainment areas. As a result, on the effective date of this rule, Imperial County will be reclassified by operation of law as a moderate 8-hour ozone nonattainment area. The moderate area attainment date for the reclassified Imperial County will be "as expeditiously as practicable," but no later than June 15, 2010. Once reclassified, California must submit State Implementation Plan (SIP) revisions that meet the 8-hour ozone nonattainment requirements for moderate areas, as required by the CAA. EPA has determined that the State must submit these SIP revisions by December 31, 2008.