NPDES Permits

The National Pollutant Discharge Elimination System (NPDES) Permit program was first introduced as part of the Clean Water Act in 1972. The goal of the permit program is to control and regulate the discharge of point source pollution into the nation’s water by issuing permits to dischargers. Drainage systems, like the City of Seattle’s drainage system, are considered dischargers.

In 1990, Phase I of the NPDES program was established, which required permit coverage for medium and large municipal storm sewer systems (MS4) which serve municipalities with populations of over 100,000 people. List of Phase I Municipalities in Washington State.

The Phase I Municipal Stormwater Permit requires that the City develop a stormwater management plan that contains 10 specific elements and conduct stormwater monitoring. To learn more about Seattle’s Stormwater Management plan and the permit please visit the City’s Stormwater Management website.

Phase II of the NPDES program unfolded in 1999 and required that smaller communities also obtain permit coverage and develop stormwater management plans. In addition, there are Industrial Stormwater Permits, which cover a wide range of industrial activities, such as manufacturing, production and maintenance and apply to individual businesses with specific standard industrial codes (SIC) or pollution generating site activities.

Nationally, the NPDES program is administered by the Environmental Protection Agency. In some states, including Washington, the authority to administer the program has been delegated to the State. In Washington, this authority belongs to the Washington State Department of Ecology (Ecology).