Far fewer salmon return to their spawning grounds in Idaho than in the past. In an attempt to increase bars survival, fisheries managers have been collecting smolts from reservoirs and piping them into barges, which then carry them down river past the last dam on the Columbia. Unfortunately, less than one percent of the transported fish return later as spawning adults. The return rate before the eight dams was much higher. Still, some people argue that barging should remain part of the recovery plan because ninety percent of the smolts are released alive.
Federal officials believe they can achieve salmon recovery by increasing the velocity of water as it flows through reservoirs. Dams could be operated to release large amounts of water during the weeks that smolts migrate to sea. With increased velocity, the migration rate could improve.
This might help salmon in some parts of the Columbia Basin, but it won't help the salmon migrating from Idaho. The reservoirs on the Lower Snake River are maintained at a full level; additional water would not move any faster through the reservoir.
Another proposal calls for dam draw-downs — reducing the amount of water behind dams to concentrate and accelerate the flow. This would also speed the journey downstream; but it poses different problems. Draw-down reduces the efficiency of turbines and increases their ability to injure fish; it would also disable bypass operations and fish ladders. And, it is very expensive.
No one proposes removing all of the dams in the Columbia River system, but people are talking seriously about altering the four dams in the lower Snake River. They are proposing that the river be allowed to flow around the concrete portions of these dams. These four dams were among the last built in the basin. Before the dams were completed, Idaho's salmon population had remained stable, even though salmon had to migrate past several dams on the Columbia. After the dams on the lower Snake were completed, however, salmon numbers dropped. Today, all of Idaho's wild salmon populations are listed under the Endangered Species Act.