Cedar River Basin

Cedar River Basin
Highlighted Area Above: Cedar River Basin

The King County Flood Control District invests resources in the Cedar River Basin to protect public safety, the regional economy and critical infrastructure.

For the purposes of the Flood District’s budgeting and planning, the Cedar River Basin includes the Cedar River, Issaquah Creek, and the Sammamish River.

The majority of the Sammamish River lies within incorporated areas including Kenmore, Bothell, Woodinville, and Redmond. A wide variety of land uses are found along the river, which was once almost exclusively agricultural. In and around city cores, land uses include moderate-density residential, business districts, and some light industrial uses.

Information about individual rivers in the basin are available below.

Cedar River Basin 

Investments in the Basin

Cedar River Capital Investment Strategy

A capital investment strategy proposes a sequence of coordinated projects to address the most critical flood and erosion risks and to restore habitat along a specified stretch of river or within a river basin.

The strategy highlights near-term, medium-term, and long-term projects and actions that were identified during an assessment of key problem areas and potential solutions.

Capital investment strategies are directed by the Flood Control District, completed by King County, and eventually approved as policy guidance by the District’s Executive Committee.

Cedar River Capital Investment Strategy

Current Basin Projects

Herzman Levee Setback and Trail Stabilization Project 
The Herzman Levee Setback and Trail Stabilization project will provide flood and erosion risk reduction along a stretch of the Cedar River about four miles east of the City of Renton. The need for the project was identified in the Cedar River Capital Investment Strategy, completed in 2017, which identified flood and erosion risks and potential solutions throughout the lower Cedar River valley.

Jan Road Neighborhood Improvements
This project undertakes improvements to Jan Road to minimize flood risk. Alternatives include raising Jan Road to improve access during flood events; setting back or removing potions of the Jan Road and Rutledge-Johnson Levees in order to reduce potential damage to the downstream Cedar River Trail Levee, which protects portions of both the Cedar River Trail and the Maple Valley Highway; and acquiring at-risk homes. The project will be designed to ensure that equivalent or better flood risk reduction remains for the houses remaining behind the levees.

Maplewood Landslide and Flood Risk Reduction Feasibility Study 
This project analyzes flood and landslide hazards and potential associated risk in the Maplewood neighborhood. It includes an analysis of existing levees to see if levee-modifications could reduce flood risks. If the landslide hazard assessment indicates the potential to increase flood risks, an additional feasibility study will be conducted to evaluate options to mitigate landslide hazards.

Sammamish River Capital Investment Strategy
This project develops a capital investment strategy for the entire length of the Sammamish River from Lake Sammamish to Lake Washington.

Willowmoor Floodplain Restoration Project 
This project reconfigures the outlet from Lake Sammamish to the Sammamish River in order to maintain or reduce current level of flood risk in the downstream river channel and along the lake shore. The project will be designed in a manner that reduces flooding impacts and improves conditions for fish listed on in the Endangered Species Act and other wildlife in the transition zone between the lake and the river.