Underwater Curtain Technology for Enhancing Downstream Fish Passage in Storage Reservoirs
Passage is an issue both for upstream migrants (usually adult fish) and downstream or outmigrants (usually juveniles). To access habitat above the reservoir, upstream migrants must locate the fishway, pass through the fishway and over the dam, and then pass through the reservoir. Outmigrants on the other hand tend to be weaker swimming fish that must pass through the reservoir, locate downstream passage routes around or through the dam, and then pass through those routes to the tailwater. Juvenile outmigrants likely are susceptible to predation that may be aggravated by exposure to turbulent flow conditions that yield injury or disorientation. Large reservoirs with confused current patterns (as influenced by temperature stratification, wind, inflows, and outflows) can pose a significant migration barrier.
The challenge with re-establishing runs lies with collecting and passing the outmigrant juveniles. We know there are many natural lakes through which smolts migrate with little apparent disorientation or delay. This spawns the question: how can we better emulate natural lakes with storage reservoirs? This research proposes to investigate the use of underwater curtain technology for enhancing downstream passage of salmon smolts in storage reservoirs.
Need and Benefit
Quality fisheries spawning and rearing habitat is at a premium. Large storage reservoirs are responsible for blocking access to many miles of prime upper watershed habitat. Developing fish runs through reservoirs will greatly enhance fish habitat and river restoration. Underwater curtains for fish guidance has been tried in a few locations and are of interest to fisheries groups, but they have not been well researched. Underwater curtains may be an effective way to re-establish historical fish runs.
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.
Underwater Curtain Technology for Enhancing Downstream Fish Passage in Storage Reservoirs (final, PDF,
By Dale Lentz
Report completed on October 03, 2012