Stormwater Basic Information

What is the NPDES Stormwater Program?

The National Pollutant Discharge Elimination System (NPDES) Stormwater Program regulates stormwater discharges from three potential sources: municipal separate storm sewer systems (MS4s), construction activities, and industrial activities. Most stormwater discharges are considered point sources, and operators of these sources may be required to receive an NPDES permit before they can discharge. This permitting mechanism is designed to prevent stormwater runoff from washing harmful pollutants into local surface waters such as streams, rivers, lakes or coastal waters.

Most states are authorized to implement the NPDES Stormwater Program and administer their own stormwater permitting programs. EPA remains the permitting authority in a few states, territories and on most tribal lands. For these areas, EPA provides oversight and issues stormwater permits.

Who is covered under the NPDES Stormwater Program?

The NPDES Stormwater Program covers the following types of stormwater discharges: 

• MS4s - Operators of large, medium and regulated small MS4s may be required to obtain authorization to discharge stormwater.
• Construction Activities - Operators of construction sites that are one acre or larger (including smaller sites that are part of a larger common plan of development) may be required to obtain authorization to discharge stormwater under an NPDES construction stormwater permit. Where EPA is the permitting authority, operators must meet the requirements of EPA's Construction General Permit (CGP).
• Industrial Activities - Industrial sectors may require authorization under an NPDES industrial stormwater permit for stormwater discharges. Where EPA is the permitting authority, operators must meet the requirements of EPA's Multi-Sector General Permit (MSGP).

Where Can I Find More Information?

EPA has produced a wide variety of  webcasts and guidance documents to help stormwater program managers develop or improve their stormwater management programs. The National Menu of BMPs has been created to educate operators on the different BMPs available to reduce stormwater pollution. EPA also created the keys to BMP performance to help operators monitor their BMPs. Additionally, many other customizable outreach documents have been developed for public distribution to increase knowledge of stormwater pollution prevention in everyday activities. EPA has also compiled a large collection of existing state and non-profit outreach information for local agencies interested in educating the public on nonpoint source pollution or stormwater runoff.

Other EPA Stormwater Web Sites

• Greening EPA, Stormwater Management - summarizes strategies to reduce environmental impacts for EPA Headquarter's facilities and operations; and provides in-depth descriptions and examples of low impact development and sustainable stormwater management practices.
• Managing Urban Runoff - provides technical information on control of urban nonpoint source pollution.
• Managing Wet Weather with Green Infrastructure - summarizes common green infrastructure approaches and key resources for research, funding and partnerships.
• Low Impact Development (LID) - provides resources on low impact development principles.
• Total Maximum Daily Loads (TMDLs) and Stormwater - provides information on waters listed for impairments from stormwater sources and the TMDLs to Stormwater Permits Draft Handbook (PDF) (211 pp, 5.67MB, About PDF) 
• NPDES Compliance Monitoring Strategy - outlines inspection and compliance goals for the entire NPDES program, including major and minor NPDES facilities, pretreatment programs, biosolids, CSOs, SSOs, stormwater, and CAFOs. This new strategy, which takes effect in 2009, places increased emphasis on wet weather issues, particularly stormwater sources, and sets ambitious targets for audits and inspections of Phase I and II MS4s, construction sites, and industrial facilities.