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Water: Stormwater

Stormwater Homepage


Image of rainstorm over a municipality Stormwater runoff is generated when precipitation from rain and snowmelt events flows over land or impervious surfaces and does not percolate into the ground. As the runoff flows over the land or impervious surfaces (paved streets, parking lots, and building rooftops), it accumulates debris, chemicals, sediment or other pollutants that could adversely affect water quality if the runoff is discharged untreated. The primary method to control stormwater discharges is the use of best management practices (BMPs). In addition, most stormwater discharges are considered point sources and require coverage under an NPDES permit. For more information about the Stormwater program, visit the Stormwater Basic Information page.

Most states are authorized to implement the Stormwater NPDES permitting program. EPA remains the permitting authority in a few states, territories, and on most land in Indian Country.


This section contains technical and regulatory information about the NPDES stormwater program. It is organized according to the three types of regulated stormwater discharges – municipal separate storm sewer systems (MS4s), construction activities, and industrial activities. It also provides links to general stormwater topics and tools available.

To access the full list of NPDES stormwater information, such as stormwater state contacts and stormwater state web sites, use the navigation tool box on the right side of this page.

To search for additional information within the NPDES program, enter a keyword in the Search NPDES box at the top of this page.

Storm Drain with No Dumping - Drains to Streams Stencil
   Basic Information
Aerial view of a Municipal Separate Storm Sewer System (MS4)
   Municipal Information

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Silt Fence at Construction Site
   Construction Information
Empty and Unused 55-Gallon Drums Outside of an Industrial Facility        
   Industrial Information

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