Reservoir Delta Morphology and Effects on Tributary Fish Passage and Habitat – A Scoping Study
The purpose of this scoping study is to understand the problem, data, tools, and models currently available for reservoir tributary sediment budgets and delta development. Information will then be used to evaluate restoration and fish passage projects that are successful with existing processes to make future projects more sustainable. The preliminary analysis will encompass all five Yakima basin reservoirs.
Need and Benefit
Channel morphology frequently changes in tributaries to Reclamation's storage reservoirs in response to hydrology, sediment, and fluctuating pool elevations. This dynamic environment presents challenges to threatened and endangered aquatic species by causing shallow depths, disconnected surface flow, and channel obstructions, thereby blocking upstream fish passage. These changes have occurred in the channels between the minimum and maximum pool elevation and within the reservoir delta, which extends upstream into the contributing tributaries. Reservoir operations and the associated effects on water level and channel morphology are especially difficult during dry years. Spawning grounds are located upstream within contributing tributaries, making fish passage crucial for local salmonid population survival.
Contact the Principal Investigator for information about partners.
Bureau of Reclamation Review
The following documents were reviewed by experts in fields relating to this project's study and findings. The results were determined to be achieved using valid means.
Reservoir Delta Morphology and Effects on Tributary Fish
Passage and Habitat—A Scoping Study (final, PDF, 2.7MB)
By Colin Byrne, Richard Visser, Timothy Randle, Nathan Holste and Abigail Eckland
Report completed on September 30, 2021