What Is Storm Water?

Where Does It Come From?
Stormwater is the water from rain, snow, and sleet that travels down our gutters into the storm drain. Before landing on the ground stormwater starts off clean. Stormwater is almost never treated and flows directly into our rivers, lakes, and streams.

As stormwater runs over the ground it collects pollutants from the land surface, roadways, sidewalks, parking lots, construction sites, business parks, etc., and is carried to gutters, storm drains, ditches and gulches, drainage ways, and finally ends up in our local rivers and streams. It is estimated that more than half of the pollution in our nation's waterways comes from stormwater runoff.

In the past, it was thought that water pollution was caused mainly by industrial and municipal wastewater treatment plant discharges. Because of this, a lot of effort was put into cleaning up these point sources of waste water. Now the effort is being expended to clean up non-point source pollution, or water pollution that is generated all over and carried to rivers and streams in pipes and ditches.

The problem with non-point source pollution is that it is very expensive to treat and discharge. Treatment facilities would have to be very large to treat storm peak flows and would sit unused more that 95% of the time. The best way to improve stormwater quality is to treat the source. Don’t let runoff get polluted in the first place. These methods are called Best Management Practices (BMPs).

Additional Resources