Stormwater

OVERVIEW

Stormwater runoff is generated from rain and snowmelt events that flow over land or impervious surfaces, such as paved streets, parking lots, and building rooftops, and does not soak into the ground. The runoff picks up pollutants like trash, chemicals, oils, and dirt/sediment that can harm our rivers, streams, lakes, and coastal waters. To protect these resources, communities, construction companies, industries, and others, use stormwater controls, known as best management practices (BMPs). These BMPs filter out pollutants and/or prevent pollution by controlling it at its source.

WHAT NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM (NPDES)?

The NPDES permit program addresses water pollution by regulating point sources that discharge pollutants to waters of the United States.

Created in 1972 by the Clean Water Act, the NPDES permit program is authorized to state governments by EPA to perform many permitting, administrative, and enforcement aspects of the program.

WHY STORMWATER MATTERS TO GROUNDWATER

In natural, undeveloped areas, a large percentage of relatively uncontaminated precipitation infiltrates the ground, thus recharging the ground water; the remaining runoff flows to nearby water bodies or evaporates. Natural physical, chemical, and biologic processes cleanse the water as it moves through vegetation and soil and into ground water. Development alters natural systems as vegetation and open spaces are replaced with new areas of impervious surfaces such as roads, parking lots, roofs, and turf, which greatly reduce infiltration and thus ground water recharge. Uncontrolled stormwater runoff collects pollutants such as sediments, pathogens, fertilizers/nutrients, hydrocarbons, and metals, which ultimately contaminate and degrade surface and ground water.

From the Ground Water Report to the Nation

Stormwater Management – Summary Sheet : Full Chapter

Additional Resources