2020 Pacific Coastal Salmon Recovery Fund: Kwoneesum Dam Removal Project

The Cowlitz Indian Tribe has completed the full removal of Kwoneesum dam and restored anadromous access to 6.5 miles of productive spawning and rearing habitat and re-established sediment and wood transport processes to benefit downstream reaches. Tribe has fully restored the former 9-acre reservoir bed and installed wood structures in Wildboy Creek and its tributaries, totaling 1.2 miles of in-stream restoration. The completed in-stream restoration actions included 35 channel spanning large wood structures (log jams) and rootwad attached whole trees in a half-mile of Wildboy Creek, downstream of the dam footprint. These structures were backfilled with thousands of cubic yards of gravel, cobbles and boulders to create velocity breaks, trap mobile sediment and backwater sections of the bedrock-dominated streambed. The instream log structures created soft water and back-water pools, that increased summer rearing habitat for juveniles, and spawning substrate for summer steelhead adults. This project is the result of the Washington Salmon Recovery Funding Board (SRFB) design project (#17-1069) funded in 2017. The PCSRF grant were funds were used in combination with WA Salmon Recovery Funding Board support, per restoration grant (RCO #20-1176), in addition to funding support by the Brian Abbott Fish Barrier Removal Board Fund, and other private sources. The Tribe, RCO, and PCSRF staff have discussed and agreed to identify certain work types to prevent redundancy or double counting; RCO will report on the Instream and Fish Passage restoration metrics and PCSRF will report Riparian Planting metrics.

Fish Passage

The removal of Kwoneesum Dam will restore fish access to 6.5 miles of productive Wildboy tributary spawning and rearing habitat and re-establish sediment and wood transport processes to benefit miles of downstream reaches. Installing in-stream logjams in a total of 1.2 miles of Wildboy Creek and within the former reservoir footprint, will increase the diversity and quantity of rearing and spawning habitat in the project area. The log structures will increase the abundance of stable spawning habitat to increase egg incubation, while also providing complex habitat diversity to benefit fry colonization and rearing. The removal of Kwoneesum Dam will drain the reservoir, thereby unobstructed cool water flowing to downstream reaches and remedying the current summertime thermal pollution issue caused by the impoundment.



Sediment reclamation/nourishment

Sort 20,000 cubic yards of reservoir excavation spoils materials generated during dam construction in 1964-65. The reclaimed spoil material will be sorted into three piles, with large cobbles/small boulders, gravels, and topsoil and utilized in channel restoration activities and riparian enhancement within the reservoir footprint. All of the native alluvium will be transported and placed in the tributary channels in the reservoir footprint or added to Wildboy creek logjams located downstream of the dam removal. Additional spawning gravels and cobble will be added to the degraded channels to provide rearing habitat for juveniles and spawning substrate for returning steelhead and coho adults.



Riparian Restoration

Promote a new riparian stand by planting thousands of native plants and trees in the newly formed floodplain in the footprint of the Kwoneesum reservoir, equal to 10 acres of riparian restoration. The proposed planting plan will be planted in high densities near the channel margins and include trees and shrub species likely to attract hungry beavers, We expect the site will be occupied by beaver colonies and develop into a mature, diverse riparian and floodplain forest to provide long-term wood recruitment supply, shade, and macrodetrital inputs.