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Sammamish Town Center (not licensed)

Stormwater Policies and Regulations

Engineering Technician

Lisa Werre
(425) 295 0573

Stormwater is a significant source of pollution in Puget Sound. Municipal stormwater systems are one of the main ways stormwater is discharged to water bodies. To minimize pollution from stormwater, cities must comply with permits.

How is stormwater regulated?

The way cities manage stormwater is regulated through a federal permit system called the National Pollutant Discharge Elimination System (NPDES). The intent of the permit is to reduce or eliminate water quality problems in our streams, rivers and lakes. It accomplishes this by controlling pollution at its source. 

How the NPDES permit works in Washington

The federal permit program regulates the discharge of stormwater and wastewater to waters of the State. In Washington State, the Department of Ecology (Ecology) implements the NPDES program on behalf of the federal government. Ecology issues the Western Washington Phase II Municipal Stormwater Permit.

The Western Washington Phase II Municipal Stormwater Permit was re-issued on August 1, 2019, and will be in effect until July 31, 2024.  This permit authorizes the City of Sammamish to discharge stormwater from its municipal separate storm sewer system (MS4) into waters of the State (i.e. Lake Washington). This requires the city to take certain actions to prevent stormwater pollution.

The full permit can be viewed at the Department of Ecology’s website: NPDES Western Washington Phase II Municipal Stormwater Permit

What does the City need to do to comply?

The permit requires the City to take action in each of the following areas:

  • Public education and outreach
  • Public involvement and participation
  • Illicit discharge detection and elimination
  • Controlling stormwater run-off from construction sites
  • Operations and maintenance of stormwater facilities after construction

Planned actions are documented each year in a Stormwater Management Program.

Compliance documentation

These documents and links are provided as part of compliance with the Western Washington Phase II Municipal Stormwater Permit: