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



Alaska Airlines 737 taking off from Sea-Tac Airport with Mt Rainier and Central Terminal in background. Photo: Port of Seattle by Don Wilson

Airport offers a glimpse at tightening stormwater regulations

How does one of the West's busiest airports deal with extreme stormwater, and what does that mean for water quality standards in the rest of the state?

Ribbon seal sighted on January 11th, 2012 a dock on the Duwamish River, Seattle, Washington (credit Matt Cleland)

Ribbon seals in the Salish Sea?

Can Puget Sound claim a new species? Ribbon seals were not previously thought to venture into the Salish Sea, but a series of sightings in Puget Sound in 2012 expands their potential range. Scientists are keeping an eye out for future sightings. 

Don Malins examines a fish during a research trip to the Duwamish estuary. Photo circa 1987. Photographer unknown.

Toxics research that changed Puget Sound history

In the 1970s and 1980s, research from a division of NOAA's Montlake Lab suddenly and irreversibly changed the way scientists and the public viewed the health of Puget Sound. Their discoveries of industrial toxics in the region's sediment-dwelling fish led to the creation of two Superfund sites, and new approaches to ecosystem management across the Sound. The man at the forefront of this research was Dr. Donald Malins, featured here as part of the Puget Sound Voices series.


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.