On May 16, 2023, the California Department of Fish and Wildlife, National Marine Fisheries Service, and Yuba Water Agency announced a plan to design and build a fish bypass at Daguerre Point Dam on the lower Yuba River (see Figure below).
At present, the dam has fish ladders on both ends of the dam that don’t work well. The plan’s conceptual design is for a bypass channel that would allow fish to circumvent the existing dam; the plan would retain the dam. The plan would reconfigure the diversion works at the dam’s south end and add effective fish screens to the agricultural diversion infrastructure at both ends of the dam.
Essentially, the bypass would operate as a long, high-capacity fish ladder that would also allow passage of sturgeon and lamprey, which cannot use the existing fish ladders. In addition to improving the upstream migration of adult fish, the bypass would also allow for more natural downstream passage of juvenile fish.
For adult salmon and steelhead migrants headed upstream to spawn in the higher-flow, cooler, and gravel-abundant 10-mile reach between Daguerre Point Dam and Englebright Dam, the bypass would likely reduce delays caused by reluctance to enter the existing ladders and by the difficult ascent up those ladders. For juveniles outmigrating downstream, the bypass could offer more natural conditions than simply spilling over the dam or seeking out the openings to the two ladders and passing downstream in the ladders. The existing features place the young fish at the mercy of native and non-native fish predators below the dam.
The bypass concept is one of several designs that could reduce existing problems at Daguerre. In addition to passage improvement, the concept could accommodate fish collection and segregation, and may be a feasible location for a conservation hatchery.
Several key elements should be added to this bypass plan, including:
- A segregation weir that that allows selective passage and capture of upstream and downstream migrants for processing and transfer.
- Predator removal, either at the segregation weir or by means of another nearby arrangement, to minimize predation below the dam. Predator control would likely benefit the entire lower Yuba system. Major predators in terms of numbers and threat below Daguerre Dam include striped bass, smallmouth bass, pikeminnow, and American shad.
- Stream habitat improvements upstream, in the bypass, and below the dam, in particular those that create refugia for juvenile salmon, steelhead, and sturgeon, and that are less favorable to the fish that eat them.
- Fish handling, processing, and holding facilities.
- A conservation hatchery for salmon and steelhead.
Alternative designs should also be fully evaluated through CEQA/NEPA and CESA/ESA processes. For example, one alternative may involve upgrading one or both of the existing ladders to include as many of the advantageous features as possible.