North Fork Snoqualmie River Confluence Revetment Removal Project

Project goals

• Avoid long-term costs of inspecting and maintaining river protection facilities that no longer protect critical public infrastructure, private property, or farmland.
• Improve natural river processes that will improve the connection between the North Fork Snoqualmie River and its floodplain.
• Improve habitat for fish and wildlife.
• Share information about floodplain management activities and nearby projects through educational signage in collaboration with King County Parks.
• Incorporate public input into the selection of the project alternative and project design.

Selected Project Alternative

Two project alternatives were considered.  Many elements were similar between both options offered:  all result in removing approximately 570 linear feet of revetment and artificial material along the riverbank. In addition, invasive plants will be removed, native shrubs and trees will be planted along the river and educational signage will be designed and installed in the project vicinity. 

Several factors were considered in the development of the two alternatives:

• The geomorphic uncertainty of how the river would reshape the newly exposed bank, potential flood risks to upstream residents
• A desire to retain mature trees as much as possible
• Recreational water user safety, and
• Potential benefits to recreation and habitat improvements.

The main difference between the two alternatives was the amount of bank grading done after the revetment removal – Alternative 1 allows the shape of the bank to largely be determined by natural river processes over time while Alternative 2 included more bank grading that would lay create a shallower slope in selected locations.

The King County Flood Control District selected Alternative 1, as shown in the image below. The project team, in collaboration with Snoqualmie Tribe staff, are now working on a more detailed design. 

Project schedule (subject to change)

Project document

Upper Snoqualmie Resilient River Corridor Management Plan