Monday February 24, 2025
The Chronicle —
A new $8 million project at the Bonneville Lock & Dam aims to make it easier for Pacific lamprey to migrate along the Columbia River.
The project, currently under construction on the Washington side of the dam, involves demolishing and redesigning the upper part of the fish ladder.
The ladder is a series of tiered concrete walls, spanning about 800 feet along the side of the dam, that fish can use to go upstream. The troublesome part of the ladder, at least for the lamprey, is known as the “serpentine section.” It features gaps in the concrete walls that create a path along series of sharp S-turns, in fast moving water that fish must navigate in the final leg of the trip around the dam.
The new design will have softer edges and fewer hard angles, making it easier for lamprey to swim through.
“We had many years of research showing that lamprey were really struggling to pass,” said Erin Kovalchuk, project manager with the U.S. Army Corps of Engineers. “That’s when we did the computer modeling and could see how high the (water) velocities were in this old S curve configuration.”