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The Green River Watershed is the land area where rainwater drains to the Green-Duwamish River. The watershed includes Black River, Springbrook Creek, Mill Creek, Soos Creek, Jenkins and Covington Creeks, Newaukum Creek, Crisp Creek, and other tributaries. This page provides information specific to the Green-Duwamish Watershed while information spanning multiple watersheds may be found on our King County watersheds information page.

For information about the area that is a source for City of Tacoma's drinking water, please see Tacoma Water's Green River Watershed page (external) or our related organizations page.

Introduction to watersheds

Green/Duwamish Watershed Strategy

Green/Duwamish Watershed Strategy from King County DNRP on Vimeo.

Notice of boating hazards

Known hazards on King County rivers
Reports of confirmed logjams and obstructions that pose a hazard to recreational river users, but does not include hazards that are not known.

Projects in the Green River Watershed

Water and land improvement projects, Green River Watershed
Use a map to locate projects related to flooding, wastewater treatment and stormwater in King County, Washington.

Flooding and hydrology

Green River flooding in 1995 Green River flooding information
Look up real time gage data, flood phase/ river crest descriptions and learn what high water means to you along the Green-Duwamish River.

Green River System-Wide Improvement Framework
Process to achieve flood-protection that satisfies multiple, competing federal mandates and legal requirements related to levee systems and the river environment.

Flood photo viewer
Use a map to look up photographs of past floods on the Green River and other rivers in King County.

Hydrologic gage data map
Look up detailed gaging station data from area creeks and rivers.

Precipitation near Howard Hanson Dam, Green River (external link)
Precipitation monitoring station data, map, and graphs courtesy of the Office of the Washington State Climatologist.

Duwamish Waterway cleanup

Find pollution-related information below under Surface water and groundwater.

Our Duwamish
Overview of the Duwamish River cleanup work that is progressing now, including FAQs and considerations for community health and environmental justice. The site describes the Duwamish community, area jobs and businesses, and how to get involved.

Duwamish Waterway superfund cleanup programs
Accomplishments to restore the Duwamish Waterway, timeline, major milestones, approaches and participants, and how to prevent future pollution.

Pollution source control reports, Lower Duwamish Waterway
Progress reports describing the status of source control activities completed by King County Industrial Waste Program and Seattle Public Utilities as part of the Lower Duwamish Waterway Superfund cleanup. In addition, King County has been conducting multiple source control studies in the Watershed.

Sediment remediation projects
Cleanup of contaminated sites in the Duwamish Waterway and Elliott Bay to enhance and restore habitat for aquatic life.

Salmon recovery

WRIA 9 salmon recovery:
Green/Duwamish River
This page provides information about the recovery of threatened salmon species in the Green/Duwamish drainage area including an overview of the planning process, scientific information, and meeting records. We welcome your participation.

Salmon recovery by subwatershed

Surface water and groundwater

Report problems: drainage and water quality 

Stormwater runoff pollution and how to reduce it

Tips on how to reduce water pollution from home, yard, car and pets

How can I help the Duwamish?

Green River Stormwater Retrofit Planning Project
Project to develop best practices for stormwater management, to improve local drainage techniques to meet future in-stream flow conditions and water quality goals in the Green-Duwamish River Watershed.

Green-Duwamish River watershed map
Drainage map displaying streams, lakes, drainage divides, and major roads in the area that drains to the Duwamish waterway and into Elliott Bay. The map is in Acrobat format. File size is 941 Kb.

South King County groundwater management area
Learn about plans to protect the aquifer in the south county area including the Green-Duwamish watershed localities of Renton, Kent, Auburn, Covington, Black Diamond, Maple Valley, Tukwila, and areas in between.

Flood related video interview by Kim Hill with Larry Phillips, Kathy Lambert, Mark Isaacson
Watch Video:
Preventing flood disasters
King County is at work this summer repairing levees
RealPlayer needed to watch this video.
Video length 22 minutes, 22 seconds.

Benthic Macroinvertebrate Study of the Greater Lake Washington and Green-Duwamish River Watersheds Reports
This report summarizes benthic macroinvertebrate data collected from a total of 130 sites in 20 sub-basins in the Green Duwamish River and Greater Lake Washington watersheds during August and September 2003 and 2003.

Green-Duwamish River Watershed quality assessment
Comprehensive study of the Green-Duwamish River water quality and the land area draining to it, to help guide policy, prioritize cleanup and restoration efforts, and protect salmon stocks from depletion.

Green-Duwamish Microbial Source Tracking Report
This report describes the results of a microbial source tracking project on the Green River.

Stormwater runoff pollution and how to reduce it
Rainstorms rinse the watershed faster when covered by hard surfaces like roofs and roads.  Learn how stormwater brings pollution, wastes and sediments into streams, rivers and lakes and how you can keep stormwater clean.

Lake information
Lake weedwatcher project

Pollution monitoring
Ongoing water quality sampling in the Duwamish Waterway, Green River and tributary creeks. Current water quality data are available for:

Endocrine disrupting chemicals in the environment
Learn about these natural and synthetic chemicals flushed daily into our waters, and discover what King County is doing to protect public health and the environment as the science and our understanding of endocrine disruptors develops.

Wastewater treatment

South Treatment plant An overview of King County's wastewater treatment plant on the Duwamish River at 1200 Monster Road SW Renton , WA 98057. Directions

Lower Duwamish sediment cleanup
Current news, announcements and documents about a superfund project to clean up the Duwamish River.

Black Diamond wastewater storage facility
The county is continuing design on an underground wastewater storage facility in the City of Black Diamond that will extend the life of existing equipment and defer the need to build additional new conveyance pipes and pumping facilities for several years.

Pacific pump station replacement project
Overview of a plan to replace a worn-out pump station in the City of Pacific and add capacity.

Combined Sewer Overflow Control Program
During heavy rainstorms, our combined sewers may exceed their capacity and the mixture of untreated sewage and stormwater is allowed to overflow into the Duwamish River and other water bodies to keep it from backing up into homes and businesses. Learn how King County is working to improve our system to control overflows.

Combined sewer overflow water quality assessment
Analysis of water and sediment quality in the Duwamish River and Elliott Bay to use as a basis for cleanup and restoration projects.

Recreation and appreciation

King County natural areas:

Look up individual properties protected in King County's open space system for their ecological and working resource values. The natural lands site provides addresses, pictures, location maps and rules for public use:

Interurban trail
Green River trail
The Interurban and Green River Trails will comprise a system of 46 miles. The Interurban Trail currently covers 14 miles from I-405 in Tukwila to 3rd Ave SW, just south of Pacific. The Green River Trail will span 30 miles from Seattle's Alki Point to King County's Auburn Narrows Park. Its completed sections traverse the industrial heart of the valley from south Seattle through Kent, connecting to a number of neighborhoods and community trails.

Soos Creek trail
The Soos Creek Trail features a gentle grade in a natural setting suitable for leisurely strolls, bicycle rides and horse rides. To find out more about this unique resource, the King County Park System offers a variety of interpretive programs and volunteer opportunities for interested trail users.

Fishing regulations and seasons (external link)
Washington Dept. of Fish and Wildlife fishing rules for Washington State including Green/Duwamish River, its tributaries and lakes within the watershed.

Known hazards on King County rivers
Reports of confirmed logjams and obstructions that pose a hazard to recreational river users, but does not include hazards that are not known.


Aerial Photograph of Lake Meridian Historic and recent aerial photographs
Aerial photos from the 1930's, 1970's and 1990's illustrating growth around Lake Meridian in the Soos Creek drainage, among other areas in King County.

Agriculture services and information
Comprehensive information related to agriculture in King County including parts of the Green River Watershed.

Comprehensive information related to forestry across King County including parts of the Green River Watershed.

Green-Duwamish Cooperative Weed Management Area (CWMA) Knotweed Project annual reports

Noxious weed infestation map
Interactive map showing location of regulated noxious weed infestations.

Green River Watershed facts:

  • Watershed Size: 492 square miles
  • River Length: 65 miles from Elliott Bay to Howard Hanson Dam
  • Population: Approx. 400,000
  • Salmon Species Present: Chinook, chum, coho, winter steelhead
  • Other Interesting Wildlife: Elk, black bear, cougar, bald eagle, osprey, blue heron
  • Number of Dams - two:
    • Howard Hanson Dam, Built 1962 and
    • Tacoma Water Supply Diversion Dam, Built 1911

For help with services in the Green River Watershed or to report a problem, please contact Josh Kahan, Green River Basin Steward, and for Newaukum Creek, please contact Tom Beavers.


Related information
Related agencies

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News and announcements

May 26, 2015
King County hosts annual meetings June 9 on the use of large wood in river and habitat projects

Green Grants for Lower Duwamish air and water quality improvements
Applications due May 15, 2015 

Apr. 22, 2015
External report, KING 5 News
Seattle launches Equity and Environment Initiative video

Apr. 18, 2015
External feature, Bellingham Herald
Trail of the week: Green River Natural Area

Apr. 3, 2015
Executive to provide grants that support local environmental projects in Lower Duwamish

Feb. 24, 2015
External article, Seattle Times
Seattle’s new seawall also a highway for fish

Feb. 23, 2015
Council adopts legislation that will benefit Green River preservation projects
Motion gives funding priority to habitat restoration efforts

Feb. 13, 2015
External article, Kent Reporter
King County prepares major plan to improve Green River levees

Jan. 25, 2015
External article, West Seattle Blog
Congratulations! Award shared by Highland Park Improvement Club, Nature Consortium, Duwamish River Cleanup Coalition

Jan. 20, 2015
External report, KING5 News
Divers removing toxins in the Duwamish River video

Jan. 20, 2015
External article, UW School of Public Health
Public Health Cafe: Cleaning up the Duwamish River: What’s Next? Feb. 3

Jan. 2015
External release, NOAA
Research finds woody debris benefits fish 

Dec. 8, 2014
Councilmembers: EPA’s Duwamish Cleanup Plan continues effort to revitalize the “lifeblood” of Seattle 

Dec. 3, 2014
External opinion, Seattle Times
Guest: Why the EPA’s plan is the best way forward for the Duwamish River

Dec. 2, 2014
External article, Seattle Times
Mammoth $342 million cleanup ahead for fouled Duwamish River

Dec. 2, 2014
Executive Constantine thanks EPA for landmark decision that enables Superfund cleanup of Lower Duwamish to move forward

Nov. 18, 2014
External article, Seattle Weekly
How Clean Should Seattle's Only River Be?

Oct. 1, 2014
External article, Yakima Herald
Proposed water quality rule tied to fish consumption

Sep. 29, 2014
Executive awards $102,000 to community efforts to restore Green/Duwamish Watershed

Sep. 28, 2014
External article, Seattle P-I
Criminal investigation into Duwamish River pollution ends quietly in civil fine

Sep. 25, 2014
External article, Auburn Reporter
Valley flood protection takes SWIF-t approach

Salmon SEEson

Sep. 11, 2014
Public meetings on Green River flood risk reduction

  • Auburn City Hall, Sep. 23;
  • Kent Courthouse Rotunda, Sep. 30

Sep. 8, 2014
Executive Constantine, Mayor Murray announce Green/Duwamish Watershed Strategy

Sep. 8, 2014
External article, MyNorthwest
Must 'think big' to clean up Green and Duwamish River system

FacebookKing County Rivers Facebook page (external link)

Jul. 10, 2014
Executive Constantine supports comprehensive approach to improving water quality

Jul. 1, 2014
Enjoy (with care) King County’s lakes, rivers and Puget Sound this July 4th

May 30, 2014
As weather heats up, King County urges caution around cold rivers, lakes, Sound

May 18, 2014
External article, Port Orchard Independent
State updating industrial stormwater permit, public comments sought

A River Reborn: Restoring Salmon Habitat along the Duwamish River video (external)

Flood reduction grants
Applications due by June 15, 2014

May 16, 2014
External column, Seattle Times
Protect water and health by updating state’s fish-consumption rate

May 20, 2014
King County hosting two meetings June 10 on placing large wood in river projects

» Archived news and announcements