Projects

Tamkaliks Side Channel Design

The Tamkaliks Side Channel Design project is located on the Nez Perce Tribe’s Homeland site in Wallowa, Oregon, approximately 2.5 miles downstream from the confluence of the Lostine and Wallowa Rivers. Historically, this area has seen extensive agricultural disturbance, road and railroad construction, floodplain encroachment, invasive weed proliferation, and residential development that have contributed to simplification and severe alteration of the stream course and drainage patterns. The resulting confined and incised channel increased stream velocities and limited the river’s capacity for natural wood recruitment, sediment transport, and localized, slow-moving water and channel-adjacent wetland communities. The channel lacked habitat complexity and, as a result, contained limited spawning and rearing habitat for Endangered Species Act-listed steelhead, Chinook salmon, coho, and lamprey.

Side channel outlet, wood structure, and constructed riffle immediately after construction.

Rio ASE took the project over from Bonneville Power Administration (BPA) when it was roughly at a 60% design. After geotechnical explorations revealed shallow bedrock, Rio altered the design to be more realistic in overall function and to increase the amount of habitat created while accommodating bedrock constraints. The final project design consisted of the development of a side channel complex adjacent to the main stem Wallowa River, including multiple inlets, wetland complexes, and robust live willow staking for revegetation efforts. The project was focused on floodplain connectivity, instream habitat complexity, and overall hydraulic diversity to increase summer and overwinter rearing habitat for juvenile salmonids. A secondary benefit of the project is the increased floodwater conveyance, reducing flood risk to neighboring properties.