Nonpoint source (NPS) pollution, unlike pollution from point sources
such as industrial and sewage treatment plants, comes from many
diffuse sources. Polluted runoff 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 watersheds through lakes, rivers, wetlands,
coastal waters, and even our underground sources of drinking water.