Adding spillway weirs or fish slides to dams on the Columbia and Snake river dams have helped young fish survive their outmigration to the ocean, according to a progress report from hydropower system operators.
A biological opinion for the hydropower system in the Columbia River Basin sets targets for fish passage over eight federal dams on the Snake and Lower Columbia, and officials say they’re on track to meet those goals by spilling more water over the dams and adding fish slides.
The report also found that while moving a large colony of Caspian terns in the Columbia River estuary helped reduce their impact on juvenile steelhead from 15 million fish in 1999 to 6.4 million in 2009, double-crested cormorant predation is still a growing concern. Together, cormorants and terns ate about 15 percent of the juvenile salmon and steelhead that reached the Columbia River estuary in 2009.
Here’s the full report: