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The Central Puget Sound Watershed of King County includes those areas draining into small creeks that flow directly into Puget Sound including creeks in cities such as Seattle (external), and includes all of Vashon-Maury Island. Other major river basins that ultimately drain from King County into Puget Sound include the Cedar River-Lake Washington Watershed, the Sammamish Watershed, the Snoqualmie-Skykomish Watershed, the Green River Watershed, and the White River Watershed.

For information about the greater Puget Sound Watershed, see US EPA's Puget Sound Watershed page (external link). A great map of Puget Sound Watershed is available from the Encyclopedia of Puget Sound (external). For information about the health of Puget Sound marine environment, see our Puget Sound marine topics page.

Introduction to watersheds

Puget Sound Partnership (external link)
Public/private group working to develop an aggressive 15-year plan to solve Puget Sound’s most vexing problems.

Basin Steward Program
Find out what Water and Land Resources' Basin Steward Program does and how to contact your Basin Stewards.

Puget Sound marine topics
Find studies and plans related to the unique, productive, and diverse marine environment of Central Puget Sound along with news and resources, such as tide tables.

Projects in the Central Puget Sound Watershed

Water and land improvement projects,  Central Puget Sound Watershed
Look up flooding, wastewater treatment and stormwater projects in King County, Washington.

Salmon recovery

WRIA 9 Salmon Recovery - Green/Duwamish and Central Puget Sound
Site provides info about the recovery of threatened salmon species in the Green/Duwamish and Central Puget Sound drainage area including an overview of the planning process, scientific information, and meeting records. We welcome your participation.

Surface water management 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, pets and so forth.

Urbanization of Aquatic Systems: Degradation Thresholds, Stormwater Detection and the Limits of Mitigation (Acrobat pdf, external)
Study concluding that "approximately 10 percent effective impervious area in a watershed typically yields demonstrable, and probably irreversible, loss of aquatic-system function."

Pollution monitoring
Ongoing water quality sampling in Central Puget Sound local creeks (refer to Vashon-Maury Island environment page for more). Water quality data are available online for:

Lakes: statistics and water quality

Lake Weedwatcher Program
Got a small boat? Interested in saving a lake from the horrors of dense weed infestations?

Beaches, nearshore and marine habitat

Puget Sound Shoreline Stewardship Guidebook
Provides info and contacts for residents of beach and bluff shorelines to learn about natural shoreline protection, manage runoff, use native plants, control aggressive non-native plants, and maintain septic systems in an ecologically friendly way.

Juvenile Salmonid Composition, Timing, Distribution, and Diet in Marine Nearshore Waters of Central Puget Sound in 2001-2002
Scientific report essential to protect and recover Puget Sound salmon stocks.

Inventory and Assessment of Current and Historic Beach Feeding Sources/Erosion and Accretion Areas for the Marine Shorelines of Water Resource Inventory Areas 8 and 9

Marine Shoreline Inventory Report: March 2004
Inventory of selected shoreline habitat features that support juvenile salmonids, presented in part using high-resolution aerial photos with overlays that classify habitat types.

Juvenile Salmonid Composition, Timing, Distribution, and Diet in Marine Nearshore Waters of Central Puget Sound in 2001-2002
Scientific report essential for protecting Puget Sound salmon from extinction and to recover depleted salmon stocks.

Saltwater Shorelines, Life on the Edge Video Series Includes Video
Watch a video that describes what affects Puget Sound beaches and their habitat, with ideas that beachgoers and shoreline property owners may like to apply to help preserve the quality of saltwater beaches and their ecosystems.

Shoreline Master Program
Learn about King County's program to protect shorelines, promote public access, and establish priorities for shoreline uses along Puget Sound, large lakes, and rivers.

Inventory and Assessment of Current and Historic Beach Feeding Sources/Erosion and Accretion Areas for the Marine Shorelines of Water Resource Inventory Areas 8 and 9
This report examines an important part of the Puget Sound nearshore ecology: the erosion of bluffs and the transport of sediment to feed beaches. It evaluates where bluffs historically eroded, where the erosion occurs today, and evaluates the expected benefits of removing bulkheads in key areas to re-establish the vital process of sediment erosion-transport-deposition.

Vashon-Maury Island nearby tide graphs, courtesy of NOAA

image of report coverState of the Nearshore Report
The first attempt to provide a comprehensive summary and an assessment of the state of our current knowledge of ecological processes and conditions, natural resources, and ecosystem health in nearshore portions of Water Resource Inventory Areas (WRIAs) 8 and 9.The intent of this report is to have, in one place, a summary of the nearshore ecosystem characteristics in WRIAs 8 and 9 that will serve as a foundation for future technical work and decision making.

Puget Sound Nearshore Environment

Small stream mouth

The Puget Sound Nearshore Environment. An illustrated presentation.

Go to

Beyond the Beach:
Learn about the Nearshore Environment and what you can do to help protect it from damage.

image of report cover
State of the Nearshore Report

Summary and assessment of the state of our current knowledge of ecological processes and conditions, natural resources, and ecosystem health in nearshore portions of Central Puget Sound. Intended to provide a foundation for future environmental work and decision making.

Plans and restoration projects

Prioritization of Marine Shorelines of WRIA 9 for Juvenile Salmonid Habitat Protection and Restoration
This report brings together biological and geological information to help prioritize where efforts can produce the best results for nearshore habitat improvement, using maps and photos to highlight high quality habitat that should be conserved and damaged habitat that should be restored. Published May 2006.

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

Elliot Bay Nearshore Substrate Enhancement
A status report on a project to restore nearshore habitat by placing cobble, quarry spall, pea gravel and oyster shell at sites near the Duwamish Head and Seacrest.


Elliott Bay and downtown Seattle
Elliott Bay and downtown Seattle

Wastewater treatment system

History of King County's Regional Wastewater Treatment Utility
Read how our region worked to keep our lakes and Puget Sound clean and healthy, including the early days of sewage treatment and disposal in King County, the birth of Metro and development of regional facilities to process the waste produced by our metropolitan area.

West Point Treatment Plant
An overview of King County's West Point wastewater treatment plant on Puget Sound.

Brightwater Treatment Plant
Regional clean water factory that treats wastewater from homes, schools, businesses and industries in north King County and south Snohomish County. The plant design integrates landscape, architecture, wildlife habitat, engineering, art, and education.

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 Puget Sound and other waters to keep it from backing up into homes and businesses. Learn how King County is working to improve our system to control overflows.

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

Hidden Lake Pump Station Replacement and Sewer Improvement Project
Shoreline area project to replace an aging pump station and add underground storage of wastewater to reduce sewage overflows into Puget Sound.


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

Forestry services and information
Find landowner services, advice and help to promote sustainable forestry in King County.

Agriculture in King County, Washington
Find services and resources specifically for farmers in King County, Washington to help agriculture thrive but to minimize environmental damage through common-sense pollution protection and soil conservation.


Science documents, Central Puget Sound Watershed

Related information

Related agencies

News and announcements

Jan. 10, 2022
External article, Seattle Times
Seattle’s huge sewage tunnel is halfway drilled. Take a look inside 

Nov. 21, 2022
King County’s state-of-the-art station in Georgetown will be ready to protect the Duwamish River and Puget Sound from stormwater pollution this rainy season 

Aug. 18, 2022
King County is removing nearly 2,000 toxic-coated pilings from the Harbor Island shoreline, improving habitat for marine life in the Duwamish River 

Aug. 16, 2022
External report, KING5
King County pollution cleanup aims to restore habitat at a vital location for salmon

Jun. 13, 2022
External article, South Seattle Emerald
StormFest combines science, environment, and students to combat water pollution 

Oct. 21, 2021
External article, Salish Sea Currents Magazine
Can 'bug seeding' improve the health of local creeks?

Jun. 8, 2021
External report, KUOW
The Salish Sea: An imperiled wonder of the Northwest 

May 18, 2021
External column, Kitsap Sun
Investments coming to help protect Puget Sound

May 16, 2021
External article, Seattle Times
King County’s culvert hunters — and a $9 billion plan to save salmon habitat

Apr. 1, 2021
Transforming King County’s approach to protecting water quality to ensure survival of native salmon and Puget Sound orcas 

Dec. 3, 2020
External article, Seattle Times
Tire dust killing coho salmon returning to Puget Sound, new research shows  

Sep. 30, 2020
Introducing Leafline, a coalition to connect Central Puget Sound with regional trails 

Jan. 21, 2020
External article, Crosscut
Lawmakers urge fish-friendly fixes to seaside properties

Jan. 15, 2020
External feature, Seattle Times
We have the know-how and no time to waste to save Puget Sound

Clean Water Healthy Habitat
Clean Water Healthy Habitat
The right investments at the right time in the right places.