Natel’s RHT runner design enables safe downstream passage across fish species.

What Fish-Safe Means

A “fish-safe” turbine causes negligible injury or mortality to all resident and migratory fish species at all life stages, as compared to natural hazards encountered during a fish’s life cycle.

Sterling and Miguel inspect fish during a turbine test at Natel headquarters

We conduct original fish passage science and use fish survival as a design constraint in our turbine design.

Why fish-safe turbines?

Downstream migrating fish want to go with the flow, but hydropower infrastructure can block migration routes. Fish migration plays a crucial role in maintaining the health of aquatic ecosystems, as it facilitates the exchange of nutrients and genetic material between different habitats, so fish passage is important not just for fish populations but for whole river ecosystems.

Fish protection at hydropower plants has typically been to block turbines with fine screens and to route fish around the turbines through low-flow fishways. This approach can still delay fish migration and expose fish to predators, and screens themselves sometimes harm fish who become trapped against them. Additionally, many fish still enter turbines where they are subject to traumatic injuries or death. Additionally, screens are costly to install and to maintain, and they also reduce overall flow, thereby lowering a plant's generation capability. Safe through-turbine passage for fish is a solution that benefits everyone, environmentally and financially.
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Natel's RHT design offers a truly fish-safe option, whereby numerous species can pass multiple dams consecutively, and owners do not have to pay to keep them out of their turbines.

Data-informed design

From the beginning, collecting information about how real fish interact with the Restoration Hydro Turbine has been an integral part of our design process. We’ve performed controlled laboratory and field studies with biologists and engineering partners from Alden Research Laboratory, Pacific Northwest National Laboratory, and Kleinschmidt Associates to understand the effects of the RHT on migratory fish species across a range of operating conditions.

Read our peer-reviewed studies:
Journal of Ecohydraulics: "Improving Survival: Injury and Mortality of Fish Struck by Blades with Slanted, Blunt Leading Edges ."
Transactions of the American Fisheries Society: "Safe Passage of American Eel Through A Novel Hydropower Turbine."
North American Journal of Fisheries Management: "Juvenile Alewife Passage through a Compact Hydropower Turbine Designed for Fish Safety."

Trout passage testing at Monroe Hydro in Oregon

Eel passage testing at Natel headquarters in California

Featured studies

Why is live fish passage testing important?

Fish passage testing is a critical step in the development and the widespread adoption of fish-safe sustainable hydropower. After extensive computer modeling and computational fluid dynamics testing, the use of fish in scientific research remains an important step in the design of the most fish-safe high-performance turbines in the world. The humane treatment of all fish used for hydropower turbine testing is vital, both ethically and scientifically. If the fish are not treated well, the research results are not useful.

Our researchers are strong advocates of animal welfare and view their work with fish as a privilege. We take our responsibility for the ethical treatment of fish in our research very seriously and abide by all rules and regulations dictated by the American Fisheries Society’s Guideline for Use of Fishes in Research. Furthermore, we ensure compliance with the National Institutes of Health Office of Laboratory Animal Welfare and their Public Health Service Policy on Humane Care on Use of Laboratory Animals.