The Environmental Protection Agency (EPA) is approving in part and disapproving in part State Implementation Plan (SIP) revisions submitted by the State of Nevada pursuant to the requirements of the Clean Air Act (CAA) for the 2008 lead (Pb) national ambient air quality standards (NAAQS). The CAA requires that each state adopt and submit a SIP for the implementation, maintenance, and enforcement of each NAAQS promulgated by the EPA, and that EPA act on such SIPs. Nevada has met most of the applicable requirements. Where EPA is disapproving, in part, Nevada's SIP revisions, most of the deficiencies have already been addressed by a federal implementation plan (FIP). For one remaining deficiency, this final rule sets a two-year deadline for EPA to promulgate a FIP, unless EPA approves an adequate SIP revision prior to that time. EPA remains committed to working with Nevada's environmental agencies to develop such a SIP revision.