Lake Washington Watershed

Location of the Hood Canal Watershed in Washington State.  Map courtesy of the EPA.The Cedar River and its many tributaries are considered some of the best salmon habitat in King County. The river flows west and northwest from the Cascade Range, traveling into Lake Washington and through the Ship Canal and the Hiram Chittenden Locks to Puget Sound. Porous glacial till in the upper watershed allows formation of a large aquifer, which feeds the Cedar and Snoqualmie River and Rattlesnake Lake.

The watershed encompasses 30 cities and approximately 22 percent of Washington’s population. The city of Seattle manages 143 square miles in the upper watershed as an ecological preserve, which provides drinking water for King County residents. The Cedar River Municipal Watershed is the only municipal watershed owned by its residents, and one of six protected watersheds nationwide.

EPA watershed profile:

Related WRIA: 08

All Puget Sound WRIAs


King County watershed profile

Friends of the Cedar River Watershed



2003 Seattle Marathon - Seward Park Photo: J Brew (CC BY-SA 2.0)

Cleaning up Lake Washington

Lake Washington was heavily contaminated by untreated sewage until extensive pollution controls by the city of Seattle. 


Muckleshoot Tribe

The Muckleshoot Indian Tribe is named after the prairie where the Muckleshoot reservation was established in 1857. The tribe’s members are descended from the Duwamish and Upper Puyallup people.

Muckleshoot Tribe Area of Concern:

The Snoqualmie River. Photo copyright King County.

King County rivers and streams

The diversity of streams in the county is a reflection of the diversity of its geography. From the small rivulets that begin high in the Cascade Mountains, to the brooks that flow gently across the lowlands, to the five major rivers of the county, there are over 4,800 kilometers (3,000 miles) of perennial streamcourses in King County.