About Juvenile Passage Routes

Migrating juvenile salmon and steelhead in the Columbia and Snake Rivers pass up to 8 dams on their way down to the ocean. The fish depend on current, and as they approach a dam the water slows and the current may be lost in the reservoir. The fish will actively search for a way downstream. This is a when they are especially vulnerable to predators.

Some dam passage routes are safer than others. The safest way is usually a spillway, an opening to release water over the dam. Some spillways are equipped with movable weirs that make them easier for fish to find.

A large volume of water also passes through the dam's turbines, and this can be a dangerous and difficult course for juvenile fish. However, fish headed for the turbines may be guided into other bypass routes, such as gatewells, that will release them safely downstream. And for those going the turbine route, new technology has made turbine passage much safer.

At some dams, the fish are guided into floating surface collectors directly upstream. These collectors attract migrants into a holding tank until the fish are safely moved downstream by pipe or truck.

passage routes around dam