Duwamish Watershed

Location of the Duwamish Watershed in Washington State.  Map courtesy of the EPA.The Duwamish-Green watershed includes some of the most productive farmland in the Northwest. It encompasses 480 square miles, including five cities and over 100 square miles of commercial forest. Despite emptying into the heart of Seattle’s downtown, the watershed supports salmon and trout that migrate from Elliott Bay each year.

Prior to the early 1900s, the watershed included drainage from the Cedar and White Rivers, but these were diverted and the Duwamish River was substantially modified between 1905 and 1912. Most of the river’s banks are lined with levees, and two dams control the flow of the river and provide water to the city of Tacoma. The Green River is also highly controlled.

EPA watershed profile:

Related WRIA: 09

All Puget Sound WRIAs


Green-Duwamish Water Quality Assessment

King County watershed profile



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