EPA is taking direct final action to approve a revision to the Maryland State Implementation Plan (SIP). This SIP revision consists of a Consent Order to Constellation Power Source Generation, Inc. for an inter-facility averaging plan for emissions of nitrogen oxides (NO<INF>X</INF>) at facilities located in Maryland and owned by Constellation Power. The SIP revision allows Constellation Power to use system-wide emissions averaging to comply with the applicable NO<INF>X</INF> reasonably available control technology (RACT) limits for 10 boiler units located at five electric generating facilities owned by Constellation Power. EPA is approving this revision in accordance with the requirements of the Clean Air Act.