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Nonpoint Source Pollution

Nonpoint source (NPS) pollution is pollution released over a wide land area, not from one specific point - location or source. NPS pollution is caused as rainfall or snowmelt moves over land or hard surfaces, such as grass, roofs, roads and parking lots. As the runoff moves, it picks up and carries away pollutants - pathogens, metals, sediment, and chemicals. The runoff finally deposits them into lakes, rivers, wetlands, coastal waters and ground waters. NPS pollution is one of the major threats to water quality in the United States. It has been linked to human health issues. EPA researchers investigate methods to:

  • predict the quantity and quality of stormwater runoff,
  • reduce the amount of stormwater runoff,
  • determine the sources of water contamination, and
  • reduce the amount of contaminants dumped into receiving waters.

EPA’s research addresses three topics:

  • NPS pollution classification
  • Stormwater runoff simulation
  • Performance assessment  of structural controls for stormwater runoff

The top three stressors causing water quality damage is sediments, nutrients, and pathogens. EPA researchers are:

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