Seattle Public Utilities Mami Hara, General Manager/CEO

Our Watersheds

Thornton Creek Water Quality Facility

Thornton Creek Water Quality Channel (2009)

Watersheds are areas of land where all of the water that is under it or drains off of it goes into the same place. Seattle contains a number of urban creek watersheds, as well as two large regional watersheds. Preserving and improving the health of our urban watershed is essential for providing healthy and livable community. The regional watersheds supply Seattle and the surrounding communities with drinking water, recreation and serve as a home for wildlife and salmon.

Urban creek watersheds not only are home to fish and wildlife, but help to filter stormwater before it enters lakes, the Duwamish River and Puget Sound. Local groups are working to slow stormwater from rushing into the creek, prevent pollution from entering the creek, and restore important native plants to protect the creek. Learn more about several of the City’s larger watersheds by checking out the follow links:

  • Thornton Creek – This watershed runs through northeast Seattle and drains 11 square miles. It is Seattle’s largest and most urbanized watershed, outfalling into Lake Washington.
  • Piper’s Creek – Located in northwest Seattle, this watershed drains 1,835 acres, or nearly 3 square miles. Much of the watershed is located within Carkeek Park with the remainder in the mixed residential and commercial Greenwood neighborhood.
  • Taylor Creek – Seattle’s fourth largest creek is located in the southeast corner of Seattle. Dead Horse Canyon channels the creek from three upper watershed ravines into Lake Washington.
  • Longfellow Creek – Located in the Delridge Valley of southwest Seattle, this drains a 2,685 acre watershed into the Duwamish River.
  • Fauntleroy Creek – The Fauntleroy Creek watershed is located on the western slope of the West Seattle peninsula. Roughly two thirds of the 98-acre watershed consists of well-established residential development. The remainder is natural space preserved by the City of Seattle, primarily as Fauntleroy Park. View a brochure about Exploring the Fauntleroy Creek Watershed (pdf).
  • Cedar River Watershed – Located 35 miles southeast of Seattle, the 90,638 acre Cedar River Municipal Watershed supports a diverse ecosystem and provides about 70% of the drinking water to 1.4 million people in the greater Seattle area.
  • Tolt River Watershed – The South Fork Tolt River is the smaller and lesser known than the Cedar River but is still essential second supply watershed in SPU’s freshwater supply system. Located in the foothills of the Cascades in east King County, it supplies about 30% of the drinking water for 1.3 million people in and around Seattle.

In addition, we are taking steps to improve water quality, conserve water and restore shorelines in an effort to improve habitat for Chinook and other salmon species within our city limits and in our watersheds.

Habitat Conservation Plan

Salmon Friendly Seattle

Ribbon-Cutting Marks Opening of the Cedar River Fish Hatchery (pdf)