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 |
