The option of dam removal was discounted due to continuing structural improvements to the Columbia Basin dams and favourable conditions that have made salmon return in large numbers. NOAA says improvements made in the past four years and plans to add experimental devices called removable spillway weirs over the next 10 years to help fish go past the dams make it no longer necessary to hold dam removal as a backup plan.
A total of 14 populations of salmon and steelhead are listed as threatened or endangered in the Columbia and Snake River basins in Washington, Oregon, Idaho and Montana. Under the Endangered Species Act, the operation of the eight major federal hydroelectric dams in the region cannot jeopardize the survival of those fish.
