Middle Fork Snoqualmie River Corridor Planning and Capital Investment Strategy
As service provider to the King County Flood Control District, King County conducted a corridor planning process for the Middle Fork Snoqualmie River which set out to analyze flood and erosion risks and develop a long-range strategy for reducing those risks. The study area encompassed the lower four miles of the Middle Fork Snoqualmie River upstream from where it joins the North Fork Snoqualmie River.
The upper Snoqualmie Valley has experienced several destructive floods in the last 20 years. These floods have posed safety risks to people, damaged homes and negatively impacted both the local and regional economy.
The planning effort involved:
- Characterizing existing physical, biological, and social conditions in the corridor.
- Identifying the location, nature, and significance of flood and erosion risks and ecological conditions throughout the corridor.
- Developing potential solutions to flood risks in the river corridor.
- Partnering with tribes, stakeholders and interested community members at key milestones throughout the planning process.
The Middle Fork Snoqualmie River Capital Investment Strategy (CIS) reflects the outcomes on the corridor planning process. It identifies a sequence of coordinated projects that address the most critical flood and erosion risks to public safety and are ecologically and financially sustainable over time.
The CIS projects are intended to:
- Increase public safety and protect infrastructure by reducing vulnerability to flood and channel erosion hazards.
- Implement cost-effective floodplain management solutions.
- Protect and improve floodplain, instream, and riparian habitats, to the degree practical.
- Provide equitable flood risk reduction outcomes through project development and implementation.
|Timeline||Process and Documents|
|Spring / Summer 2018 - COMPLETED
Project Scoping and Data Collection
|Fall 2018 and 2019 – COMPLETED||
Meeting summary presentations and notes:
|Fall 2018 – Winter 2019 - COMPLETED||
Data Analysis and Identification of Possible Solutions
|Summer 2020 - COMPLETED||
Capital Investment Strategy
The Capital Investment Strategy is a sequenced action plan for implementing flood risk reduction efforts in the Middle Fork Snoqualmie River Corridor. A motion adopting the Middle Fork CIS as policy guidance was passed by the King County Flood Control District on August 19, 2020.
In addition to input from local residents, the project included collaboration with the City of North Bend, the City of Snoqualmie, the Snoqualmie Indian Tribe, the Tulalip Tribes of Washington, local Chamber of Commerce, Eastside Fire and Rescue, Si View Parks District, Mountains to Sound Greenway Trust, state regulatory agencies and other stakeholders.
Files are provided in Adobe Acrobat.
- Channel Migration in the Three Forks Area of the Snoqualmie River (PDF, 6MB)
- Geomorphic Assessment: Middle Fork Snoqualmie River, Tanner to Three Forks Natural Area, June 2013 (PDF, 34MB)
- Hydraulic Modeling and Analysis: Middle Fork Snoqualmie River, Tanner to Three Forks Natural Area, May 2016, updated May 2016 (PDF, 62.2MB)
- Ecological Resources Characterization: Middle Fork Snoqualmie River, Tanner to Three Forks Natural Area, September 2013 (PDF, 15MB)
- 2013 King County Flood Hazard Management Plan Update
- 2006 King County Flood Hazard Management Plan
- "So You Live Behind a Levee," American Society of Civil Engineers' brochure (external link)
For questions about this project and actions underway, contact Chrys Bertolotto, Project Manager, Snoqualmie/South Fork Skykomish River Basins, King County River and Floodplain Management Section.