The King County Flood Control District invests in regional programs and projects that reduce the risk to people and property from river flooding and channel migration in King County. King County is home to several river watersheds that carry water flows from the Cascade Mountains to Puget Sound. These rivers pass through forested, agricultural and highly urbanized areas. Flooding is a significant threat.
Historically, rivers in King County have flooded in every month with the exception of August. River flooding has led to 13 presidentially declared disasters in King County since 1990 with the most recent being declared in 2020.
The conceptual map below shows the major rivers served by the District: Cedar, Green, Raging, Sammamish, Snoqulamie, South Fork Skykomish, Tolt, and White. These rivers are grouped into the river basins outlined below.
About the Seattle Basin
The King County Flood Control District invests resources in Seattle to protect public safety, the regional economy and critical infrastructure.
About the Cedar/Sammamish/Issaquah River Basin
The King County Flood Control District invests resources in the Cedar/Sammamish/Issaquah River Basin to protect public safety, the regional economy and critical infrastructure.
About the Snoqualmie/South Fork Skykomish River Basin
The King County Flood Control District invests resources in the Snoqualmie/South Fork/Skykomish River Basin to protect public safety, the regional economy and critical infrastructure.
Investments & Projects by River Basin
Cedar River Basin
The Cedar River Basin runs northeast within the boundaries of King County and includes the Cedar and Sammamish rivers and Issaquah Creek. Read more.
Green River Basin
The Green River Basin is located in the south quadrant of King County and stretches from the County’s boundaries from west and east. In addition the the Green River, major tributaries in this basin include Soos, Newaukum and Mill creeks, and the Black River. Read more.
Snoqualmie/South Fork Skykomish River Basin
The Snoqualmie River/South Fork Skykomish River Basin is located in northeast King County and includes the Lower Snoqualmie, Raging , South Fork Skykomish, Tolt, and Upper Snoqulamie rivers. Read more.
White River Basin
The White River Basin is located in the southern most portion of King County, and includes the boundary line between King and Pierce counties. Read More.
The King County Flood Control District’s work plan is guided by the 2006 King County Flood Hazard Management Plan which serves as the comprehensive map of development for flood control and floodplain management and identifies up to $335 million in critical flood protection repairs to aging flood risk reduction infrastructure throughout King County. Read more about the District’s plans, strategies, and guiding documents.