Over a third of our nation’s streams, lakes, and estuaries are impaired by some form of water pollution (U.S. E.P.A. 1998). Pollutants can enter surface waters from point sources, such as single source industrial discharges and waste-water treatment plants; however, most pollutants result from nonpoint source pollution activities, including runoff from agricultural lands, urban areas, construction and industrial sites, and failed septic tanks.