NPDES Stormwater Permitting Program

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 wetlands. To protect these resources, communities, construction companies, industries, and others, use stormwater controls, known as best management practices (BMPs). These BMPs reduce pollutants and/or prevent pollution by controlling it at its source.


The NPDES stormwater program regulates stormwater discharges from three potential sources: municipal separate storm sewer systems (MS4s), construction activities, and industrial activities. Operators of these sources are required to obtain coverage under an NPDES permit before they can discharge stormwater. This permitting mechanism is designed to prevent stormwater runoff from washing harmful pollutants into local surface waters.


Federal, state and local governments have passed law and regulations to address the problem of polluted runoff. Phase I EPA stormwater regulations initiated a national stormwater permitting program in 1990, which applied to industrial activities, to construction sites of five acres or more and to urban runoff from larger cities. Phase II regulations in 1999 address additional urbanized areas, certain cities with population over 10,000, and construction activities of one to five acres. The Tennessee Department of Environment and Conservation, Division of Water Resources implements the EPA Phase I and Phase II regulations in Tennessee.

Stormwater Permitting Program Areas

Whom Do I Contact For More Information?

Please contact your local TDEC Environmental Field Office.