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The Sammamish watershed is part of the greater Lake Washington - Cedar River drainage, encompassing the land area in which rainwater drains to Lake Sammamish, Bear Creek, the Sammamish River and out into Lake Washington.

Community service center
Information about King County's satellite offices including the Issaquah Community Center in the Sammamish Watershed. Office address is 5415 220th Ave SE (inside the Issaquah District Court building), phone number 206-477-2169.

Brightwater Education and Community Center
New sustainably-built facility and surrounding park located near Bothell and Woodinville, available host school and community events, indoors or outdoors.

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

Surface water and groundwater

Introduction to watersheds

Report problems: drainage and water quality

The Restore and Protect Project
Project to identify habitat stressors and recommend restoration and protection actions to improve freshwater quality and aquatic habitat in Puget Sound streams including Stensland and Tibbetts Creeks in the Sammamish Watershed.

Stormwater runoff pollution and how to reduce it

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

Lake Sammamish
Learn about the history of the lake including its past and current pollution problems, kokanee populations and what King County is doing to protect the lake.

  • Lake Sammamish water quality data
    This page offers an overview of Lake Sammamish water quality issues and provides graphs of water quality data from several sampling locations on the lake, spanning years. Graphs display temperature, dissolved oxygen, pH, conductivity, nitrogen, phosphorus, chlorophyll, bacteria, transparency, and other data.

Swimming beach data
Find information about levels of bacterial pollution and relative health risks at swimming beaches on Lake Washington, Lake Sammamish and other King County lakes.

Pollution monitoring
Rivers and streams: ongoing water quality sampling in Sammamish Watershed streams and rivers. 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?

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.

Redmond-Bear Creek Valley Groundwater Management Area
Issaquah Valley Groundwater Management Area
Learn about plans to protect the aquifer in areas spanning the Sammamish watershed including Woodinville, Redmond, Sammamish, Issaquah and areas in between.

Bear Creek Basin Plan
Assessed the condition in Bear Creek drainage basin, predicted future changes based on development pattern and recommended ways to reduce flooding, erosion and sedimentation in the stream and to protect valuable stream, wetland and fishery habitat.

Bear Creek Watershed-Scale Stormwater Plan
Outlines actions and strategies that will restore Bear Creek so that it provides healthy habitat for Chinook salmon and other aquatic species.

Issaquah Creek Basin Current/Future Conditions & Source Identification Report
Analysis of the area draining to Issaquah and Tibbetts Creeks, documenting conditions of surface waters and identifying sources of pollution.  Published in 1991.

Issaquah Creek Basin and NonPoint Action Plan
Recommendations to manage flooding, pollution and aquatic habitat in Issaquah Creek and its tributary streams.  Published in 1994.

Sediment quality evaluation in Lake Sammamish, Lake Union, and Lake Washington
Report of chemical and biological substances, their distribution and toxicity, and benthic communities at various sample sites.

Major Lakes Continuous Temperature Study
Describes results of continuous temperature monitoring in Lake Washington, Lake Union and Lake Sammamish to help understand aquatic ecosystem response to the changing climate.

Development of 3-D Hydrodynamic Model of Lake Sammamish
Describes the development, modifications, calibration, and testing of an abstract model to analyze and understand Lake Sammamish.

Sammamish River Diel pH and DO Study
This study provides data to support the identification of dissolved oxygen, pH and temperature problems in the Sammamish River that affect its aquatic life. The data will also support the development of water quality modeling tools that can be used to evaluate various management options proposed to mitigate problems.

Development of a Water Quality Model of the Sammamish River
Describes the development, modifications, calibration, and testing of the Sammamish River model.

Sammamish Watershed MapSammamish Watershed map (426 KB  Acrobat)
Drainage map displaying streams, lakes, drainage divides, major roads, in King County and Snohomish County portions of the Sammamish River Watershed.

Issaquah Creek map

Salmon recovery

Lake Sammamish kokanee
Describes the dwindling population of genetically distinct kokanee in Lake Sammamish and actions that King County and other agencies are doing to protect and restore them.

Lake Sammamish Urban Wildlife Refuge Partnership
Extensive effort to support conservation of fish and wildlife in the Sammamish Basin, and contribute to the quality of life for current residents and future generations.

Sammamish kokanee videos
Kokanee releases and returns on creeks along Lake Sammamish.

Lake Washington, Cedar River and Sammamish (WRIA 8) salmon recovery
This site provides information about the recovery of threatened salmon species in the Sammamish, Lake Washington, and Cedar River drainage area including an overview of the planning process, scientific information, and meeting records. We welcome your participation.

Greening your Shoreline
References and recipes for lakeshore property owners on Lake Sammamish and Lake Washington can use to improve shorelines for people and salmon.

Predicting Climate Change Effects on Kokanee Habitat Suitability in Lake Sammamish
Report on the application of 2-D and 3-D temperature models of Lake Sammamish to evaluate future climate change impacts on kokanee habitat.

Water Resource Inventory Area (WRIA) 8 plans, studies and maps

Flooding and hydrology

Issaquah Creek flood information
View real-time gage data and map for Issaquah Creek and learn about expected conditions at various flood phases.

Hydrologic gage data map
Look up detailed gaging station data for creeks in the region.

Lake Sammamish flooding frequently asked questions (FAQs)
Find answers to questions about flooding near Lake Sammamish.

Wastewater treatment

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.

Recreation and appreciation

Swimming beach data - water temperature, bacteria and algal toxin measurements

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:

Nature at Brightwater Center

Sammamish Valley tourism & recreation map guide 
Outdoor recreation opportunities and points of interest for residents and visitors around Redmond and Woodinville, Washington.

East Lake Sammamish Trail
This scenic and safe regional trail hugs Lake Sammamish and runs from the city of Issaquah to Redmond, connecting Lake Sammamish State Park at the south end with King County's Marymoor Park at the north end of Lake Sammamish.

Burke-Gilman Trail
Sammamish River Trail
King County's beloved regional trail hugs Lake Washington and the Sammamish River to provide a link between the Cities of Seattle, Lake Forest Park, Bothell, Redmond and the crown jewel of our parks system, Marymoor Park.

Marymoor Park
The largest and most diverse destination park in King County's portfolio of Parks. Provides hundreds of acres of nature and offers a wide variety of recreation options including birdwatching, rock climbing, fishing, off-leash dog walking, bike racing, team sports, outdoor concerts and movies and just being.

Fishing regulations and seasons (external link)
Washington Dept. of Fish and Wildlife fishing rules for Washington State including Sammamish River, Lake Sammamish and their tributaries, and lakes within the watershed.

Lake Shorelines, Life on the Edge Video Series 
Watch a video that describes lakes in King County and how residents value them, with ideas that shoreline landowners may like to apply to help preserve the quality of lakes and lake ecosystems.


Aerial Photograph of Cottage Lake

Historic and recent aerial photographs
Aerial photos from the 1930's, 1970's, and 1990's illustrating growth around Cottage Lake, among other areas in King County.

Quality assurance project plan for regulatory effectiveness monitoring for developing rural areas
Framework to monitor and evaluate land use regulations to help ensure their effectiveness, using indicators for hydrology, water quality, biology, and stream complexity.

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

Agriculture in King County, Washington
Comprehensive information related to agriculture in King County including parts of the Sammamish Watershed.


Science documents - Sammamish Watershed

Related information

Related agencies

News and announcements

Sign-up for Sammamish kokanee news:

Jan. 25, 2023
Executive Constantine announces $52 million for 36 projects that will protect greenspace, restore habitat, conserve tree canopy, increase access to homegrown food 

Oct. 13, 2022
Amid promising signs of health for native kokanee salmon, recovery partners release young fish into Lake Sammamish that were flown in from an Orcas Island hatchery

Oct. 6, 2022
External article, Seattle Times
Buttigieg wades into Northwest salmon transportation 

Sep. 22, 2022
‘Salmon SEEson’ returns: Where to spot fish as they come home to spawn in King County rivers and streams 

Jun. 2, 2022
Biologists see promising signs of health for native kokanee salmon four years after Executive Constantine announced actions to help ensure their survival 

May 19, 2022
Executive Constantine announces plan to rapidly accelerate protection of the last, best 65,000 acres of urban greenspace, forests, farmland, trails, river corridors, and natural areas

Mar. 2, 2022
External report, FOX 13
Last offspring of Kokanee salmon return from Orcas Island

Jan. 22, 2022
External report, KING5 News
King County, Snoqualmie Tribe, partners continue efforts to restore Kokanee population 

Dec. 1, 2021
External article, Snoqualmie Valley Record
Kokanee salmon make a comeback in Zackuse Creek  

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

Oct. 5, 2021
External article Seattle Times
Sammamish, like many suburban Seattle cities, gripped by development fight as region’s population booms 

Jun. 6, 2021
External article, Seattle Times
The enchanting world of beavers in King County — and how they might benefit a warming planet

Protecting, restoring the Bear Creek watershed

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 

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