Stormwater runoff occurs when precipitation from rain or snowmelt flows over the land surface. It is commonly collected in storm sewers and, in many cases, is discharged to waterways untreated. The addition of roads, driveways, parking lots, rooftops and other surfaces that prevent water from soaking into the ground can degrade the quality of water entering our streams, lakes, and rivers. The Nationwide Urban Runoff Program (EPA, 1983) found 77 of 127 priority pollutants tested were detected in urban stormwater runoff. Contaminants commonly found in stormwater runoff include heavy metals, organic compounds, pesticides and herbicides, pathogens, nutrients, sediments, and salts and other deicing compounds. Surface waters that are used as sources of water supply routinely receive contaminants carried in stormwater runoff.

To reduce the impacts of runoff on waterways, the EPA requires municipalities to obtain permits for discharges of stormwater runoff. As a result, most states and local governments have adopted regulations requiring developers to install stormwater management practices that reduce the rate and/or volume and remove pollutants from runoff generated on their development sites. In an effort to better understand how stormwater discharges are regulated the Urban Issues Workgroup maintains a comparison of state stormwater standards.

Additional Resources

State Stormwater Programs
Maryland
Virginia
West Virginia
Pennsylvania

Stormwater Permit Regulations
U.S. EPA Region 3 Stormwater (Click on “Stormwater”)

EPA Source Water Protection Practices Bulletin
Managing Stormwater Runoff to Prevent Contamination of Drinking Water

The Center for Watershed Protection offers free access to certain publications and other resources that support best practices in watershed and stormwater management.

References
U.S. EPA, 1983. Results of the Nationwide Urban Runoff Program, United State Environmental Protection Agency, Water Planning Division, WH‐554, Washington D.C.