What types of construction activities require a storm water permit?
In 1987, Congress amended the Clean Water Act (CWA) to require implementation, in two phases, of a comprehensive national program to control pollutants that enter the “waters of the United States” via storm water runoff. The storm water program is now part of the National Pollutant Discharge Elimination System (NPDES) permit program, which was established by the CWA to regulate point source discharges from municipal and industrial sources, including certain construction activities. The EPA finalized the first phase of the storm water program on November 16, 1990 (55 FR 47990). Currently, Phase I requires NPDES storm water permits for discharges from construction sites that disturb five acres or more of land to surface waters or into a municipal separate storm sewer system (MS4). Storm water discharges from activities that disturb less than five acres also must be covered by a Phase I permit if they are part of a “larger common plan of development or sale” with a planned disturbance of
