Nutrient pollution – nitrogen and phosphorus – is one of the top pollutants in our rivers and streams. Nitrogen and phosphorus are found in fertilizers and human and animal waste. On land, they help plants and crops grow, but are often overused and end up in our water supply. When too many nutrients end up in our rivers and streams, they cause algae to bloom in the warmer months. When the algae dies and decomposes, it sucks the oxygen out of the water, creating large "dead zones" where aquatic life cannot survive. The dead zones are a cause for concern in the Potomac and Shenandoah Rivers, where they have been associated with large fish kills and human health concerns.

You can read more about nutrient pollution in our blog. To learn more about what Potomac Riverkeeper and Shenandoah Riverkeeper are doing to control nutrient pollution from small farms, visit our Site by Site Agricultural Project.