Non-point Source Pollution
Non-Point Source (NPS) Pollution occurs when rainfall, snowmelt, or irrigation runs over land or through the ground, picks up pollutants, and deposits them into rivers, lakes, and coastal waters or introduces them into ground water.
NPS pollution represents the most significant source of pollution overall in the country. More miles of rivers and acres of lakes are impaired by overland runoff from rowcrop farming, livestock pasturing, and other types of nonpoint sources than by industrial facilities, municipal sewage plants, and point source runoff. More than 40 percent of all impaired waters were affected by nonpoint sources, while only 10 percent of impairments were caused by point source discharges alone.
Examples of non-point sources:
Storm Sewer
Row Crop Farming
Livestock Pasturing
Atmospheric deposition is also a form of nonpoint source: pollutants discharged into the air and returned directly or indirectly to surface waters in rainfall and snow, as well as so-called dry deposition between precipitation events. (Of course, "smokestack industries" such as fossil-fueled electric generating plants could be considered "point sources of air pollution". But the diffuse deposition of pollutants emitted by such facilities is a form of nonpoint source in the context of water pollution.)
Atmospheric Deposition
Pollutants commonly associated with NPS include nutrients (phosphorus and nitrogen), pathogens, clean sediments, oil and grease, salt, and pesticides.
Acknowledgement:
http://www.epa.gov/watertrain/cwa/right52.htm |
