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Cedar River corridor planning, funded by the King County Flood Control District, set out to analyze flood and erosion risks to people and infrastructure and to develop a long-range strategy for reducing those risks.

The study area encompasses 22 miles of the Cedar River valley, from Landsburg Road SE to Lake Washington.

The planning effort involved:

  • Characterizing existing physical, biological, recreational and social conditions in the corridor;
  • Identifying the location, nature, and significance of flood and erosion risks and ecological needs throughout the corridor;
  • Developing concepts for project and program actions to reduce vulnerability to flood risks and prevent or mitigate impacts to habitat or other valued uses in the river corridor; 
  • Developing a comprehensive and strategic approach to implementing capital improvement projects; and
  • Partnering with stakeholders at key milestones throughout the planning process.

The outcome is a Capital Investment Strategy proposing a sequence of coordinated projects to address the most critical flood and erosion related public safety risks.

Proposed actions are intended to:

  • Reduce vulnerability to flood risks for residents;
  • Protect public infrastructure;
  • Minimize disruption to the regional economy as a result of flooding;
  • Protect habitat and other community values;
  • Partner with residents, community groups, and other resource agencies to share information and develop projects that provide multiple benefits.
Attached is the final Cedar River Capital Investment Strategy. It highlights the near-term, medium-term, and long-term actions that were identified in this planning process and that address a range of critical flood and erosion risks. The strategy was presented to the Flood Control District's Executive Committee in June 2017, which approved it as policy guidance. Also attached are the strategy report's Project Summary Sheets, the Habitat Enhancement Opportunities Technical Memo, the project location map and the implementation schedule for the capital investment strategy.

Public involvement

An important element of this project was to engage the community, especially those directly affected by floods and flood-related hazards in this area, and gather input about the long-term vision and priorities for the Cedar River.

In February 2015, King County convened an Advisory Committee to provide input and two-way communication at key milestones of the Cedar River corridor planning effort. Members represent property owners, river and corridor users, non-profit interests, business interests, government agencies, and the public at large. A Recreation Work Group was also convened and provided recreation-focused input to the Cedar River Advisory Committee. All Advisory Committee meetings and Recreation Work Group meetings were open to the public.

A recreation workshop was hosted on June 15, 2015, to engage the community in interactive mapping and discussions about recreation in the corridor. The workshop was well attended and the ideas shared will help inform project alternatives.

A public meeting was held on May 18, 2015, to present planning goals and objectives of the approaches to addressing flooding and flood related hazards.

To stay informed about Cedar River planning and future capital investment projects, please sign up for Cedar River corridor announcements.

Process and schedule

Jan. - Oct. 2014


  Project scoping and data collection
Characterize the existing conditions of the Cedar River related to:
  • Human uses;
  • Flood, erosion, and channel migration risks; and
  • Aquatic and floodplain habitat. 

Nov. 2014 - June 2016          


  Data analysis and identification of alternative solutions 
Analyze existing problems and identify various alternative solutions to reduce flood risks and foster habitat restoration, such as:
  • Setting back levees or removing them all together to open up the floodplain to safely absorb and convey floodwater;
  • Altering or improving infrastructure such as roads or bridges to reduce disruption to the regional transportation network; and 
  • Acquiring flood and erosion-prone homes and properties from willing landowners to remove people from risk and allow the river to move without impacting people.

July 2016 - June 2017



Final report and recommendations
The Capital Investment Strategy Report will define and prioritize existing floodplain conditions, uses, problems, and potential solutions relative to physical, biological, and socio-economic factors within the Cedar River corridor.
The final report will include project design concepts and cost estimates and a proposed strategy for implementation. The Capital Investment Strategy Report is intended to support the King County Flood Control District in setting flood risk reduction priorities in the Cedar River corridor.

The Cedar River Capital Investment Strategy was presented to the Flood Control District Executive Committee in June 2017. The strategy, which highlights near-term, medium-term, and long-term actions the County should take to address identified risks, now provides policy guidance and direction to the County.

Funding and partnerships

This project is funded by the King County Flood Control District (external link).

In addition to working with the Advisory Committee, the project will include collaborating with the City of Renton, the City of Seattle, the Muckleshoot Indian Tribe, regulatory agencies, landowners, the community and other partners and stakeholders.

For questions about this project contact Nancy Faegenburg, Project ManagerRiver and Floodplain Management Section, Water and Land Resources Division.