A thick, slanted Restoration Hydro Turbine runner is shown installed in a runner housing.

FishSafe™ engineering by Natel, manufacturing by trusted industry partners.

FishSafe™ Design

Natel’s patented FishSafe™ designs allow fish to pass directly through the turbine, eliminating the need for fine screens, nightly shutdowns, or other compromise solutions. FishSafe™ RHTs are available in Francis, Kaplan, and propeller-style designs for a range of head heights.

High performance
Natel’s runner designs combine through-turbine fish passage with resistance to cavitation and up to 94% peak hydraulic efficiency. Natel works in partnership with established turbine manufacturers to provide FishSafe™ runners or turbines of any diameter for sites with a wide variety of head and flow characteristics. FishSafe™ RHTs can be directly integrated with existing civil works, providing the lowest cost option for meeting downstream passage requirements while simultaneously modernizing aging plants. Natel rigorously tests design performance at our California hydraulic test facility. Performance tests measure flow, pressure, torque, and speed of scale-model turbines and are conducted to the American Society of Mechanical Engineers PTC-18 standard.
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Exceptional through-turbine fish passage
Natel’s patented FishSafe™ Restoration Hydro Turbine (RHT) designs feature thick, forward-swept blades that have consistently demonstrated 98-100% fish passage survival for a range of aquatic species, including eel, salmonids, sturgeon, and alosines. This unique shape is informed by laboratory blade strike studies, CFD modeling, and numerous fish passage tests.
the thick and forward-swept design of FishSafe™ turbine blades allows them to pass fish downstream directly through the turbine.
propeller runner comparison FishSafe™ RHT v conventional
Kaplan-style FishSafe blade vs conventional blade
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screens vs no screens plant graphic
High Economic Value

Natel’s FishSafe™ turbines provide a smarter, more cost-effective path to plant modernization. Savings in both CapEx and OpEx enable two to ten times the accelerated return on investment:

Eliminate costly fish passage measures
Meet downstream passage requirements at no extra cost, saving money spent on fine screens or lost to plant shutdowns.

Lower maintenance costs
In addition to eliminating fine screen cleaning costs, the unique shape of FishSafe™ blades minimizes sediment wear and extends service life, saving owners money on blade repairs. 

Generate more power
Increase output by up to 10% by avoiding flow losses to bypasses and head losses to fine screens.

Read the peer-reviewed paper about FishSafe™ cost savings
Abrasion resistance
The same innovative design principles that allow Natel’s FishSafe™ turbines to function as a fish passageway also provide significant advantages in reducing hydro-abrasive erosion. The thick, rounded leading edges that characterize FishSafe™ turbine designs reduce sediment impact velocity and create a stagnation effect that minimizes abrasion. For plants in mountainous regions with heavy sediment loads, this could mean substantial economic benefits and reduced downtime—all while supporting exceptionally fish-friendly operations.

In tests following IEC Standard 62364, FishSafe™ blades showed up to 78.5% less wear in high-sediment conditions compared to conventional turbine blades. This translates to: 5x longer blade life in sediment-heavy environments, reduced maintenance costs due to extended intervals between repairs, and consistently higher turbine efficiency over time.
Read the white paper
Broad application
By enabling effective downstream fish passage at the same speed and power point as conventional turbines, FishSafe™ RHT designs allow for straightforward equipment replacements with little to no change in civil works or generator specifications.

FishSafe™ RHT runner designs span a wide operating range. Working with established manufacturing partners, Natel can provide FishSafe™ propeller, Kaplan, or Francis-style RHT runners or turbines of any diameter for a wide range of head heights. Learn more about our highly-regarded turbine manufacturing partners.
View our references
FishSafe Francis turbine, vertical.
FishSafe Kaplan turbine, horizontal.
FishSafe Kaplan turbine, vertical.
FishSafe propeller turbine, vertical.
FishSafe Kaplan runner replacement, vertical.
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