Riverbend Levee Setback and Floodplain Restoration
Cedar River - Lake Washington Watershed
Construction crews are demolishing and removing 60 vacant mobile homes and three additional structures. The demolition work is expected to be completed by Oct. 25, 2017.
In response to community feedback, construction hours will not begin until 8 a.m. and finish by 6 p.m, Monday through Saturday. If necessary, some work may be done on Sundays, from 10 a.m. to 6 p.m., to stay on schedule.
Restoration Design Update
During Fall 2017, King County scientists and consultants will be conducting fisheries surveys and evaluating the condition of Cavanaugh Pond in support of the Riverbend Levee Setback and Floodplain Restoration Project.
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The Riverbend Levee Setback and Floodplain Restoration Project builds upon a long-term effort to protect public safety and restore salmon habitat by acquiring property and relocating residents from a flood-prone portion of the Cedar River floodplain.
The project goals are to:
- Restore riverine processes and functions in the Cedar River and its floodplain in order to improve the quality, quantity, and sustainability of salmonid spawning and rearing habitat;
- Reduce flood and erosion risks to people, property, and infrastructure;
- Accommodate public use consistent with future ecological conditions at the site; and
- Balance flood and ecological benefits and other objectives with project costs.
The preliminary project design includes partial removal of levees and revetments, floodplain grading to create side channel and backwater habitat, installation of wood to provide channel stability and habitat, and native vegetation planting.
Previous land use within the project area significantly modified the site topography. The current Cavanaugh Pond site was the borrow pit for a gravel mining operation on the Cedar River, resulting in a deep artificial pond. The Riverbend Mobile Home and RV Park site was filled to facilitate development. Therefore, in order to restore natural floodplain dynamics with active side channel and backwater habitat, the upstream portion of the project site must be lowered and the bottom of Cavanaugh Pond must be raised.
This project is recommended in the Lake Washington/Cedar/Sammamish Watershed (WRIA 8) Chinook Salmon Conservation Plan. This project is among the highest priority recommendations in the Lower Cedar River Basin and Non-point Pollution Action Plan (adopted by the King County Council in July, 1997) and the Lake Washington General Investigation Study Project Recommendations (issued by King County and the U.S. Army Corps of Engineers, September 2002).
The project site is located on public property along the left bank of Cedar River between River Miles 6.5 and 7.5 east of Renton in unincorporated King County. The project site encompasses Cavanaugh Pond Natural Area and the previous site of the Riverbend Mobile Home and RV Park, which King County purchased in 2013.
- Improve in-stream and off-channel habitat for Chinook and other salmonids by increasing channel complexity, creating more diverse flow conditions and facilitating more direct connections to floodplain habitats;
- Reduce flood and erosion risk to people, property and infrastructure;
- Restore floodplain connectivity to approximately 40 acres of floodplain to increase flood storage, dissipate energy and increase the capacity of the reach to accommodate the deposition and storage of sediment and large wood;
- Revegetate approximately 25 acres of floodplain and riparian buffer to provide terrestrial habitat, shade, cover and future wood recruitment to the river;
- Where feasible, setback levee/revetment along the left bank to allow channel migration and re-initiate natural riverine processes.
The project is located in a high priority reach of the Cedar River and it builds on the adjacent Cedar Rapids Floodplain restoration project. Increasing the area available for the channel to widen and side channels to form in this part of the Cedar River is expected to benefit Chinook and other salmon species on a watershed scale.
|Acquisition and Resident Relocation
|Planning and Preliminary Design||2015-2016|
|Final design||Spring 2017 - Winter 2018|
- Riverbend Levee Setback and Floodplain Restoration Project Alternatives Analysis Report, October 2016 - 4.2 MB PDF
- 30% Design, March 2017 - 14 MP PDF
Project design and implementation funding
- Floodplains by Design Partnership
- King County Water and Land Resources Division
- Washington State Salmon Recovery Funding Board
- King County Flood Control District
- City of Seattle
For more information about the Cedar River Riverbend Project, please contact Jon Hansen, project manager, Ecological Restoration and Engineering Services Unit.