PNNL

Dams can serve multiple purposes, including electricity generation and flood protection, but can also disrupt the natural migration of fish. Some dams have purpose-built mechanisms that support fish passage, like bypass systems and ladders designed so that fish can pass through or around dams, but not all dams have fish passage mechanisms. 

Fish reintroduction is the intentional establishment of a fish species in an area where it existed historically prior to hydropower development and other terrain changes to the species’ habitat. Reintroduction is needed for some migratory fish species, such as salmon, to re-establish populations on the other side of upstream obstructions that they cannot cross on their own. Reintroduction is valuable because fish migration contributes to the health of rivers and productive aquatic ecosystems, which provide economic, cultural, and recreational value to communities. Native American Tribes, such as the Winnemem Wintu, Spokane Tribe of Indians (STI), Coeur d’Alene Tribe of Indians (CDAT), and the Confederated Tribes of the Colville Reservation (CTCR) as part of the Upper Columbia United Tribes (UCUT), are leading efforts to reintroduce salmon and other fish species in currently blocked areas of rivers to restore cultural keystone species that were lost following dam construction.

The process of reintroducing fish to historically occupied habitats involves examining the habitat areas, gathering past and current fish population numbers and behavioral data, and observing how fish move upstream and downstream to identify how they would re-establish and survive. Reintroduction efforts in the United States have involved teams with expertise from many disciplines and industries to coordinate across hatcheries, researchers, hydropower staff, and local, state, and federal natural resource agencies, including Native American Tribes, to facilitate accurate research on the feasibility of reintroduction and inform decisions on reintroduction efforts. 

Salmon Reintroduction with the Upper Columbia United Tribes 

The Spokane, Coeur d’Alene, and Colville Confederated Tribes are leading the UCUT salmon reintroduction efforts in the upper Columbia River watershed in Washington state. Researchers at Pacific Northwest National Laboratory (PNNL) provided support during the first phase of their efforts, from 2015 to 2019, which included providing estimates of Chinook salmon habitat upstream of Grand Coulee Dam and assisting with study design for the UCUT and Tribes’ Phase 2 implementation plan. PNNL’s work, as well as support from other organizations, helped to inform lifecycle models that are guiding the reintroduction effort by providing information about how donor stocks, disease risk, current habitat, and other survival factors may impact fish reintroduction efforts. 

Phase 2 of the salmon reintroduction effort began in 2021 and is anticipated to continue through 2040. This phase started with cultural releases of adult salmon and is expanding to include juvenile fish survival studies, consideration of adult salmon trap-and-haul programs, development of rearing facility possibilities, and designing and testing fish passage options to assist fish in migrating around Grand Coulee and Chief Joseph dams. 

As of 2024, PNNL provided technical assistance during Phase 2 of the plan by helping develop the experimental design using the Juvenile Salmon Acoustic Telemetry System for fish survival evaluations and assistance with rearing sockeye salmon for survival studies. PNNL is in the process of assisting the UCUT and Tribes with survival evaluations of juvenile sockeye salmon under the guidance of the Phase 2 implementation plan. 

Shasta Dam Salmon Reintroduction

The Shasta Dam in California currently impedes migration of Chinook salmon (called Nur by the Winnemem Wintu Tribe) to the McCloud River (called Winnemem Waywaket by the Winnemem Wintu Tribe). Reintroduction efforts are being led by the Winnemem Wintu Tribe, NOAA Fisheries, and the California Department of Fish and Wildlife. PNNL is providing technical assistance to these partners, along with the California Department of Water Resources. 

PNNL’s technical assistance work related to this reintroduction effort includes the development of a novel sediment filtering device, known as a water particle separator, at a remote salmon incubation location; an anti-fouling coating for underwater netting being used to direct the migration of juvenile salmon at a prototype fish capture facility; as well as technical assistance in design of an acoustic telemetry array to evaluate the system. 

PNNL’s Technical Assistance in Fish Reintroduction

PNNL provides technical assistance to Tribes and natural resource management agencies engaged in salmon reintroduction efforts in Washington and California. In these regions, technical assistance supports partners who are working to implement fish passage improvements and habitat restoration to overcome obstructions to fish migration, with the goal of increasing fish population sizes and making populations more resilient. 

Some ways that PNNL researchers provide technical assistance support are through the use of advanced acoustic tags to track fish passage and behavior as they move through dams, data and feasibility analyses, and the development of new technologies to monitor and support fish passage and development.

Clean water is critical to supporting the rearing of salmon. In rivers, rocks and gravel protect the salmon eggs from predators, while also preventing sediment in the water from covering the eggs. In a hatchery, technology is needed to provide that protection. An example of a PNNL-developed technology supporting fish reintroduction is water particle separators, which are devices that prevent the water feeding into hatchery and egg incubation systems from accumulating sediment which could harm egg development. This flow-through unit is unique in that it does not require a filter, operates on very little head pressure, and does not use electricity to operate.

Another example of a technology developed to support fish reintroduction is the protective coatings on nets used to collect or redirect fish being transported for reintroduction. Nets are used to guide migrating fish to specialized capture structures where they can be safely removed and transported by vehicle around a river barrier like a dam. The specialized coatings, called Superhydrophobic Lubricant Infused Composite (SLIC), are being tested to understand and improve formulations that may reduce the growth of microorganisms (known as “biofouling”) on the nets, increasing the longevity of the equipment. PNNL’s work on these antifouling coatings has led to advancements in the variety of surfaces these coatings work on, as well as more techniques for applying the coatings.