Introduction to Stormwater Pollution

Every time it rains, some of the water runs off of the land. This is known as stormwater runoff. As it flows off of rooftops and lawns, and down driveways and streets, stormwater picks up pollutants and debris.

This can include such things as:
Sediment (dirt)
Fertilizer
Pesticides
Motor Oil
Grease
Heavy Metals (lead, copper, zinc, cadmium)
Leaves and Grass Clippings
Pet Waste
Litter

All of these contaminants are carried by stormwater (now known as polluted stormwater runoff) to the nearest storm drain or drainage swale and are eventually delivered, untreated, into the nearest river, lake or stream.

Stormwater pollution can make monitoring and treatment of our drinking water more difficult and costly. In addition, it can hinder the health of the aquatic ecosystem and result in the loss of our rivers, lakes and streams for recreational purposes.

Source: http://www.cleanwatercampaign.com/html/531.htm