The U.S. Department of Energy reports that a California company has developed a turbine for small hydropower projects enabling juvenile fish to pass through with 100 percent survival, according to preliminary results of Pacific Northwest National Laboratory tests.

"Early conclusions from PNNL's analysis, which will be published in a full report in early 2021, determined that 100% of the fish passed through the [turbine] without any harm or significant disturbance," the release states.

PNNL used live rainbow trout and Sensor Fish—a small device with sensors to measure a fish's experience, including acceleration, pressure, velocity and orientation—to gauge impacts to fish passing through the Monroe Drop Site, a U.S. Bureau of Reclamation irrigation canal in Madras, Ore. The canal was fitted with a 1.9 meter diameter Restoration Hydro Turbine (RHT) developed by Natel Energy, an Alameda, Calif., company.

One test involved 60 juvenile trout traveling through a draft-tube exit in the tailrace, which were compared to 60 juvenile trout released into the plant intake and passed through the turbine at maximum power. Sensor Fish were also sent through both systems so physical stressors could be analyzed. Tests revealed a 100 percent survival rate for fish up to 15 inches long.

The turbine uses compact, fish-friendly blades between 1 and 3 meters in diameter, for use on low-head dams with between 2 and 10 meters of hydraulic head. The turbines can be installed as retrofits for existing turbines, at dams that currently don't generate power, or at run-of-river developments and irrigation canals, the agency said.

"These results provide important evidence that, if designed correctly, small hydropower facilities do not have to compromise between generation efficiency and biological performance," DOE's Dec. 10 news release said. "This is the first time that a turbine with the dimensions of the D190 RHT has achieved these kinds of results, and is a highly promising step toward a more robust deployment of the technology in the near future," the release said.

A 2012 DOE report determined that more than 80,000 dams do not produce electricity, and after looking at 54,000 of them, determined nonpowered dams have potential to add up to 12 GW of new power capacity.

K.C. Mehaffey covers fish issues for Clearing Up, and is editor of the NW Fishletter. She joined the NewsData writing team in February 2018. From lawsuits to scientific studies, she is enjoying the deep dive into the Columbia Basin's many fish topics.