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— Map from the United States Environmental Protection Agency
All across the country, municipal separate storm sewer systems, known as MS4s, are required to protect bodies of water from pollution. The federal Environmental Protection Agency implemented the MS4s in two phases: The 1990 Phase I required medium and large cities and certain counties to get federal permits for stormwater discharges; there are about 855 Phase I MS4s covered by 250 permits. The 1999 Phase II required small MS4s — like the one in Voorheesville — in urbanized areas to get permits; most of the 6,695 Phase II MS4s are covered by state permits. Regulated MS4 areas cover 4 percent of the land in the United State and serve more than 80 percent of the population, according to the EPA.