National Pollutant Discharge Elimination System ( NPDES ) - National Pollutant Discharge Elimination System , the two-phased surface water quality program authorized by Congress as part of the 1987 Clean Water Act . This federally mandated system is used for regulating point source and nonpoint stormwater discharge . The second phase of the program requires local governments to implement the following six minimum measures :
1 . Public Education and Outreach 2 . Public Participation / Involvement 3 . Illicit Discharge Detection and Elimination 4 . Construction Site Runoff Control 5 . Post-Construction Runoff Control 6 . Pollution Prevention / Good Housekeeping
Natural buffer - A variable width area maintained with natural vegetation between a pollutant source and a waterbody that provides natural filtration and other forms of protection .
Nonpoint-source pollutants - Pollutants from many diffuse sources . Nonpoint-source pollution is caused by rainfall or snowmelt moving over and through the ground . As the runoff moves , it picks up and carries away natural and human-made pollutants , finally depositing them into lakes , rivers , wetlands , coastal waters , and even underground sources of drinking water .
Outfall - The point of discharge from a river , pipe , drain , etc . to a receiving body of water . Point-source pollutants - Pollutants from a single , identifiable source such as a factory or refinery . Pollutant loading - The total quantity of pollutants in stormwater runoff .
Polluted runoff - Rainwater or snowmelt that picks up pollutants and sediments as it runs off roads , highways , parking lots , lawns , agricultural lands , logging areas , mining sites , septic systems , and other land-use activities that can generate pollutants .
Porous pavement and pavers - Alternatives to conventional asphalt that utilize a variety of porous media , often supported by a structural matrix , concrete grid , or modular pavement , which allow water to percolate though to a sub-base for gradual infiltration .
Retention - The process of collecting and holding surface and stormwater runoff with no surface outflow .
Runoff - Water from rainfall , snowmelt , or otherwise discharged that flows across the ground surface instead of infiltrating the ground .
Sanitary sewer system - Underground pipes that carry only domestic or industrial wastewater to a sewage treatment plant or receiving water .
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