By Steven Schauer, Deputy Executive Director

On March 14, people around the world will unite to celebrate the International Day of Action for Rivers. This global observance is dedicated to recognizing the vital importance of rivers for people, ecosystems, and the planet. It also serves as a call to action to protect and defend rivers from threats such as pollution, fragmentation, irresponsible infrastructure development, and climate change. The theme for this year’s celebration is centered around “Protect Rivers, Protect People” highlighting how the health of rivers directly shapes the future of communities and ecosystems everywhere.

Rivers are more than flowing water. They provide fresh water, support biodiversity, regulate climate, and sustain cultural traditions and livelihoods. But many rivers globally are under threat from pollution, climate change, and other human pressures that disrupt natural processes and degrade water quality. International Day of Action for Rivers brings communities together to advocate for free-flowing, healthy waterways and the rights of people who depend on them.

King County’s Major River Watersheds

King County is rich in freshwater systems that shape our landscapes, communities, and natural habitats. Six major river watersheds dominate the region, each with unique characteristics and contributions.

Cedar River

Flows from various creeks in the Cascade foothills form the Chester Morse Lake and Masonry Pool, behind the Masonry Dam (aka Cedar River Dam), which was constructed in 1914. The dam is still operated by the City of Seattle, providing hydroelectric power to the city. Today, the Cedar River begins below the dam, flowing from the Cascades into Lake Washington in the city of Renton. Its upper watershed is protected and managed to provide drinking water to more than a million residents in the greater Seattle area.

At Landsburg, about 18% of the river’s flow is diverted for Seattle’s drinking water. The remaining water continues its journey to Lake Washington and eventually the Puget Sound. This watershed supports important salmon recovery efforts (WRIA 8), flood risk reduction infrastructure, water quality monitoring, and community watershed stewardship.

Green & Duwamish Rivers

The Green River begins in far southeast King County, near Blowout Mountain deep in the Cascade Mountain Range. Traveling through the Cascades, gathering flows from numerous creeks and tributaries, the Green River fills the Howard A. Hanson Reservoir. Beyond the Howard A. Hanson Dam, which is operated by the U.S. Army Corps of Engineers, the watershed features extensive flood risk reduction infrastructure, water quality sampling sites, salmon recovery efforts (WRIA 9), pollution remediation efforts (including Superfund cleanup), and recreation along the Green River Trail and other natural areas.

The Green River flows through parts of Auburn, Kent, Renton, SeaTac, Tukwila, and unincorporated King County. The river is home to a diverse community of nearly 30,000 residents and serves as a major economic engine for Washington, contributing one-eighth of Washington State’s Gross Domestic Product. The Green River also supports valuable farmland, life-saving medical facilities, cherished parks, vibrant community centers, natural habitats crucial to salmon populations, and key transportation routes connecting people and goods.

In the City of Tukwila, the Green River flows into the Duwamish River, which in turn flows through the City of Seattle, ending in the Puget Sound at Elliott Bay. The Duwamish River is Seattle’s only river. It flows past the South Seattle neighborhoods of Georgetown and South Park, and through Seattle’s industrial core. Unfortunately, because of this industrial history, the last five miles of the Duwamish River towards Elliott Bay is considered one of the most polluted rivers in the nation. The U.S. Environmental Protection Agency (EPA) declared the Lower Duwamish Waterway a Superfund Site in 2001, which requires the nation’s most toxic sites to be identified and cleaned up.

While the Howard A. Hanson Dam provides significant flood risk reduction, flooding on the Green and Duwamish rivers remains a risk to people, infrastructure, and natural resources. To address flood challenges in the lower Green River area, the King County Flood Control District is developing a long-term vision for reducing flood risks and protecting this vital region. You can learn more about the planning process and get engaged in the Partner Planning Committee by visiting the Lower Green River Corridor Flood Hazard Management Plan webpage.

Sammamish River

The Sammamish River Watershed includes land draining to Lake Sammamish (like Issaquah Creek), Bear Creek, and the Sammamish River, which empties into Lake Washington in the city of Kenmore.  Lake Sammamish and the Sammamish River supports diverse wildlife, recreational opportunities, and urban communities, including Issaquah, Sammamish, Redmond, Woodinville, Bothell, and Kenmore as well as unincorporated areas of King County.

The watershed is home to important flood risk reduction infrastructure (especially for Issaquah Creek and the Sammamish River), rich surface water management and pollution monitoring networks, and Lake Sammamish water quality sampling. Salmon conservation (WRIA 8) is also a central focus of this watershed.

Snoqualmie River

Covering the largely rural eastern portion of King County, the Snoqualmie River is made up of flows from off the Cascade Mountains. The Snoqualmie Valley is home to the iconic Snoqualmie Falls and is an important agricultural region in King County known for farming, logging, and natural beauty. The area includes flood risk reduction infrastructure together with robust flood monitoring and the Snoqualmie Fish, Farm & Flood initiative, habitat restoration, salmon recovery (WRIA 7), and natural asset preservation along trails and open lands.

The Snoqualmie River is also known for being prone to flooding. For planning purposes, the river is sometimes divided into two reaches separated by the iconic Snoqualmie Falls. Above the falls is the Upper Snoqualmie River, which includes the North Fork Snoqualmie River, Middle Fork Snoqualmie River, and South Fork Snoqualmie River. The cities of North Bend and Snoqualmie are in the Upper Snoqualmie River reach.

The Lower Snoqualmie River begins below the falls and ends at the county line between King County and Snohomish County, where the river continues until its convergence with the Snohomish River. (It’s the Snohomish River that finishes the journey to the Puget Sound.) The Lower Snoqualmie River reach flows past the rural town of Fall City and the cities of Carnation and Duval. It also receives additional flow from tributaries like the Raging and Tolt rivers.

South Fork Skykomish River

The South Fork Skykomish River is in the far northeast corner of King County. From the confluence of the Tye and Foss rivers, the South Fork Skykomish River is formed about 13 river miles upstream of the county line between King and Snohomish counties. It is a relatively unpolluted and free-flowing river running through the incorporated town of Skykomish and unincorporated communities of Grotto and Baring. The Miller River is a tributary of the South Fork Skykomish River a short distance downstream from Skykomish. The State of Washington has designated many portions of the South Fork Skykomish as scenic.

The South Fork Skykomish River is in an isolated area of King County serviced only by Hwy 2, the east-west thoroughfare traveling through Stevens Pass. Fun fact: from anywhere else in King County, the only way to visit the South Fork Skykomish River is to first leave King County. As the South Fork Skykomish River continues through Snohomish County, it meets with the North Fork Skykomish River, becoming the Skykomish River, near the town of Index. Where the Skykomish River meets the Snoqualmie River is the beginning of the Snohomish River, which empties into Puget Sound at Port Gardner in Everett.

White River

Glacier melt from Mount Rainier, combined with melting snow and rainfall from the surrounding area, creates the White River. The heavy sediment in the water from the melting glaciers gives the river its milky white color, which is where it gets the name White River. In total, the White River flows 68 miles and is part of a watershed spanning 494 square miles. It supports multiple salmon species, as well as elk, bears, eagles, and more. Within King County, the White River features flood risk reduction infrastructure, flood detection systems, sediment and stormwater management, and recreation opportunities.

Beginning in Pierce County, the White River becomes the county line boundary between Pierce and King counties where the Greenwater River joins the White River. Mud Mountain Dam, a short distance southeast of Buckley, was built on the White River by the U.S. Army Corps of Engineers in 1948, and it provides flood risk management protection on the White and Puyallup river. The White River flows through the Muckleshoot Reservation. It flows through King County and the cities of Auburn and Pacific before returning to Pierce County, where it eventually joins the Puyallup River near the City of Sumner. The Puyallup River enters the Puget Sound in the City of Tacoma.

How King County Residents Can Take Action

While International Day of Action for Rivers highlights global advocacy, protecting local rivers is something every resident can contribute to year-round. Here are ways to get involved:

💧 Reduce Pollution at the Source

• Dispose of hazardous household waste properly; don’t pour paints, oils, or chemicals down storm drains.
• Pick up pet waste and avoid excess fertilizer on lawns — both can wash into streams and rivers.

🌱 Restore and Protect Habitat

• Participate in or organize river cleanups and native planting events.
• Support efforts to restore floodplains and wetlands that improve water quality and fish habitat.

🚶‍♂️ Learn and Share

• Attend educational events, watershed tours, or webinars to learn about river ecology and floodplain functions.
• Share what you learn with neighbors and community leaders to raise awareness about river protection.

📣 Advocate for Healthy Rivers

• Contact elected officials about policies that protect water quality and reduce harmful development impacts.
• Support local organizations working on conservation, habitat restoration, and sustainable water management.

Rivers are the lifeblood of our communities. They are essential for clean water, thriving ecosystems, cultural heritage, and a resilient future. Whether through international solidarity on March 14 or everyday stewardship here in King County, we all have a part to play in protecting the rivers that sustain us.