US EPA is proposing to approve revisions to the South Coast Air Quality Management District (SCAQMD) portion of the California State Implementation Plan (SIP). These revisions concern oxides of nitrogen (NOx) and oxides of sulfur (SOx) emissions from facilities emitting 4 tons or more per year of NOx and/or SOx in the year 1990 or any subsequent year. US EPA is proposing to approve local rules to regulate these emission sources under the Clean Air Act as amended in 1990 (CAA or the Act). These rules are part of the SCAQMD’s Regional Clean Air Incentives Market (RECLAIM) program. US EPA is taking comments on this proposal and plan to follow with a final action.