Phases of the NPDES Stormwater Program

Phase I

In response to the 1987 Amendments to the Clean Water Act (CWA), the U.S. Environmental Protection Agency (EPA) developed Phase I of the NPDES Stormwater Program in 1990. The Phase I program addressed sources of stormwater runoff that had the greatest potential to negatively impact water quality. Under Phase I, EPA required NPDES permit coverage for stormwater discharges from:

• Medium and large municipal separate storm sewer systems (MS4s) located in incorporated places or counties with populations of 100,000 or more;
• Eleven categories of industrial activity which includes construction activity that disturbs five or more acres of land

Operators of the systems, facilities, and construction sites regulated under the Phase I NPDES Stormwater Program must obtain permit coverage for the stormwater discharge leaving sites.

A summary of the Phase I Program is available in the Overview of the NPDES Stormwater Program [PDF Format]

Phase II

The Phase II Final Rule, published in the Federal Register on December 8, 1999, requires NPDES permit coverage for stormwater discharges from:

• Certain regulated small municipal separate storm sewer systems (MS4s); and
• Construction activity disturbing between 1 and 5 acres of land (i.e., small construction activities).

In addition to expanding the NPDES Stormwater Program, the Phase II Final Rule revises the no exposure exclusion and the temporary exemption for certain industrial facilities under Phase I of the NPDES Stormwater Program and certain exemptions relating to ISTEA. The Phase II Rule also established two potential waivers for small construction activities.

• 2003 Construction General Permit
• Stormwater Phase II Final Rule Fact Sheet Series
• National Menu of Best Management Practices for NPDES Stormwater Phase II
• National Menu of Best Management Practices for NPDES Stormwater Phase II Downloadable Files
• Measurable Goals Guidance for Phase II Small MS4s
• Urbanized Area Maps

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Last updated on January 10, 2008 11:27 AM
URL:http://cfpub.epa.gov/npdes/stormwater/swphases.cfm