Couse Creek is a tributary that flows into the Walla Walla River near Milton-Freewater, OR. Tributary habitat is limited in the Walla Walla Basin, and restoration actions at River Mile 4 are intended to improve spawning and rearing habitat for Mid-Columbia Steelhead. Couse Creek is listed in regional steelhead recovery plans as a primary spawning area for the Walla Walla River population. Limiting factors for native fish in Couse Creek include stream temperature, uniform streambed material, low frequency of wood, and reducing duration of seasonal surface flows. WWBWC is working with local partners and funders to implement treatments to increase aquatic habitat complexity, floodplain connectivity, and support riparian vegetation. The long-term objective of this project is to improve conditions for steelhead in Couse Creek by providing refuge for juveniles, enhancing spawning conditions for adults, and decreasing stranding mortalities due to thermal barriers and dry stream reaches.
Project Schedule:
- 2022: Design document completed, permitting and environmental compliance
- 2023: 38 natural wood structures installed
- 2024: 49 natural wood structures installed
- 2024: invasive species removal and riparian planting
- Ongoing: monitoring and adaptive management to protect investment and ensure objectives are met
Funding:
- Oregon Watershed Enhancement Board
- Bonneville Power Administration
Below: Aerial view of several structures and the new pool and gravel bar formation visible within 6 months of construction. 
Restoration Approach:
Natural wood structures were constructed within the Couse Creek channel and adjacent floodplain to jumpstart the hydraulic processes that create a diverse, productive ecosystem that is also resilient to flood, drought, and fire. WWBWC and partners built Post-Assisted Log Structures (PALS) that simulate natural wood accumulations and Beaver Dam Analogues (BDAs), which mimic the structures created by beaver, nature's engineers. These structures were built using a variety of locally sourced material and installed using manual labor and small equipment, resulting in minimal impact to existing riparian vegetation and in-stream habitat.
These new structures will drive hydraulic diversity that will lead to habitat complexity. Adding structure to Couse Creek will force overbank flows, create the hydraulic diversity necessary for sorting sediments, and inundate a greater extent of riparian communities over a wider range of flow stages. These outcomes have been linked to more suitable habitat because they nourish the development of bars and pool-riffle sequences and attenuate the effect of peak discharges by dispersing high energy runoff to the surrounding floodplain. Improvements to the riparian zone will provide important cover and refuge for all life stages of steelhead.
Visit our interactive page showing before/after conditions in the River Mile 4 project reach.
Below: The natural wood structures activated new side channels and braids during the first winter after construction.
