The objective of this project is to remove a rock weir and concrete structure that were placed in the mainstem Okanogan River in the 1940’s or 1950’s. This section of the Okanogan River is a popular float with kayakers and canoeists, due to the lack of development in the floodplain. Removal of these structures will enhance the aesthetic value of this reach and increase boater safety. Additionally removal of these objects will restore natural flow regime, sediment transport/storage, and floodplain connectivity of Wilson Side Channel, which is part of a floodplain complex recently purchased by WDFW directly below the site of the project.
The weir proposed for removal extends out across the head of the secondary channel for 110ft and is comprised of large 2-4ft angular rock. During low flow periods, the weir diverts the majority of water away from the side channel and ultimately downstream of the Wilson side channel. The photo above shows the weir at approximately 2,000cfs, and the Okanogan River during most years will drop below 1,000cfs for several months at a time. Removal of the weir will allow increased flows to the secondary channel and increase frequency of high flow/side channel activation. Removal will also restore sediment transport and storage to the side channel. This action would mitigate for the oversimplified channel that has resulted from decades of human manipulation.
Project Partners:Colville Confederated Tribes
Project Funders: Washington Department of Ecology