The Environmental Protection Agency (EPA) is proposing an approval and a limited approval and limited disapproval of a revision to the Mojave Desert Air Quality Management District (MDAQMD or ``District'') portion of the California State Implementation Plan (SIP). We are proposing approval of five rules and a limited approval and limited disapproval of five rules. These revisions concern the District's New Source Review (NSR) permitting program for new and modified sources of air pollution under part D of title I of the Clean Air Act (CAA or ``Act''). If finalized, this action will update the MDAQMD's current SIP with ten revised rules. We are taking comments on this proposal and plan to follow with a final action.