Researchers Testing Green Peter Dam’s “Fish Waterslides”

In an ongoing effort to improve fish survival at various Willamette Project dams, the US Army Corps of Engineers is trying a slightly wacky new approach to getting baby fishes downstream and past the dams safely. An unused pipe system at Green Peter Dam is being tested as a method of sending juvenile fish to safety, waterslide-style.

Down the Tubes

Following a 2008 biological study, the National Marine Fisheries Service asked that measures be implemented to ensure that at least 98 percent of young salmon make it downstream safe and sound. The mothballed pipes in the 327-foot-high dam on the Middle Santiam River may represent the perfect solution.

Late last month, researchers sent Chinook and steelhead salmon smolts from Santiam Hatchery through the tubes to assess the plan’s viability. The fish were placed in tanks at the top of the dam, accompanied by a handful of fish-sized sensors that measured speed, pressure, temperature, and other factors. A stopper was removed, and the tanks drained into the pipes, sending the fish and sensors on 300-foot ride to the bottom of the dam.

There, the test riders were gathered into another tank for 48-hour observation. Researchers checked the live fish for scrapes, concussions, and other injuries that may have been sustained during the 60-plus second journey. A vast majority of the fish survived the trip and the ensuing observation period.

“It’s like going down a giant waterslide,” said Fenton Khan, a biologist working at the test site.

An Effective & (Relatively) Inexpensive Solution

Similar pipe systems at other dams—such as the Detroit Dam (463 feet high), the Cougar Dam (452 feet), and the Lookout Point dam (276 feet)—could be put to similar use if the tests at Green Peter go as well as researchers hope.

Detroit Dam

Detroit Dam

The only other proven solution involves trapping the young fish above the dams, hauling them downstream by truck, and releasing them back into the river. While effective, this is a time consuming process with numerous ongoing costs, including paying fish catchers and truck drivers.

Though the upfront costs of modifying the pipes for fish passage could be high, in the long term, this option would save money. “If we can use the [pipe system] that’s already sitting there never operating [at Detroit Dam], we can save a lot,” said Jeff Ament, the project manager in charge of fish passage at Detroit Dam. “But we can’t just do it on a whim. The question is, is it healthy for fish?”

Biologists continue to study the fish as they travel farther downstream.

Photo credit: reidab / Foter / CC BY-NC-SA