The Columbia River is the largest dam in the Northwest United States. The Snake River is its largest tributary. At one time the Columbia River was the most productive salmon river in the country. It now has 14 hydroelectric dams, which impede migration in both direction. The Snake River has another 15 dams. Salmon are anadromous; they are born and breed in fresh water but live most of the time in salt water. Many of the dams on these two rivers have fish ladders to allow adult salmon to return to their breeding grounds. And some of the dams have facilities to help young salmon swim to the ocean. Young salmon are also put in barges and carried towards the ocean. But these facilities and operations do not work that well. And other types of fish are hurt by the dams. Fish ladders must be designed for particular species, and one type of fish ladder may work well for only one species. Recent studies have shown that fish ladders may not work well at all: http://e360.yale.edu/feature/blocked_migration_fish_ladders_on_us_dams_are_not_effective/2636/
The Bonneville Dam is the last (or first) impediment to migration. The dams on the Snake River and much further inland. Many organizations have advocated for the removal of the Lower Snake River dams (some seen below), since they produce relatively small amounts of electricity.
Fish Ladder, Bonneville Dam, Oregon
Fish Ladder, Bonneville Dam, Oregon
Fish Ladder, Bonneville Dam, Oregon
Fish Ladder, Bonneville Dam, Oregon
Upstream, Ice Harbor Dam, Washington
Lock, Little Goose Dam, Washington
Little Goose Dam, Washington
Fish Ladder, Little Goose Dam, Washington
Fish Return Facility, Little Goose Dam, Washington
Fish Return Facility, Little Goose Dam, Washington
Fish Return Facility, Little Goose Dam, Washington
