NON-POINT SOURCE POLLUTION

Click on the words below to learn about a specific kind of NPS pollution

SEDIMENT

PATHOGENS

NPS pollution presents a subtle water quality problem because it originates from widely dispersed and diverse sources, not a single outlet. Natural forces such as rain or wind often play a key role in transporting pollutants to stream systems.

Examples of NPS pollution are soil from eroded fields and development sites; chlorinated swimming pool water drained into storm sewers or directly to streams; runoff from backyards containing fertilizers and pesticides; pet wastes, motor oil, paint thinner, or antifreeze dumped in storm sewers; and motor oil and other substances that wash off streets and parking lots.

With rain, no matter the amount, comes serious pollution washing from the land into lakes, bays, rivers, coulees, and aquifers. Where stormwater cannot soak into the soil, it runs off, eroding exposed land and filling street gutters.

The onrush of rain water sweeps accumulated dust, dirt, debris, organic matter, and toxic pollutants from roads, construction sites, and lawns into city storm sewer lines and sometimes directly into surface waters. Farm runoff may channel water muddy with sediment, fertilizer and pesticide residues, salt, and animal wastes into streams and larger bodies of water. The adverse impacts of NPS pollution relate to how close sources are to waterbodies, land use, type of soil, and slope of the land, although pollutants from distant sources may reach the same waterbodies after several storms.

NPS pollution is not restricted to a single area. 99% of sediment, 88% of nitrates, and 84% of phosphates entering the United States' lakes and streams are considered NPS pollution.

Effects of NPS Pollution

Poison fish, aquatic animals, and wildlife.
Cover fish spawning beds, killing fish eggs.
Act as a grinding mechanism on stream beds, destroying aquatic life residing on the stream bottom—from macroinvertebrates to fish and reptiles.
Increase decomposition of organic debris, depleting the oxygen in water that is necessary to support aquatic animal life.
Fill in streams and reservoirs.
Add nitrates and phosphorous to water causing extensive algae blooms and the potential death of lakes and estuaries.

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