The stormwater requirements of the federal Clean Water Act are administered under the Pennsylvania Department of Environmental Protection’s Municipal Separate Storm Sewer (MS4) Program. In December 2002, DEP issued a General Permit (“PAG-13”) for use by MS4s that fall under the National Pollutant Discharge Elimination System (NPDES) Phase II program, requiring the implementation of a stormwater management program for minimizing the impacts from runoff.