Several federal agencies, the state, public utility districts, cities, counties, and private businesses own and operate dams. Many of us have been fortunate to live in a state with cheap, abundant, non-polluting hydroelectric power. Dams used for irrigation have also created economic opportunity for farm communities, especially in the dry areas of Eastern Washington. Dams have helped make our state what it is today. Many older fish ladders don't work very well and need to be replaced with newer, more fish-friendly designs.
Dams also impede young fish as they migrate downstream on their way out to sea.
The lakes behind dams slow the fish down, because they reduce the velocity of the river's current. This can be critical to fish that have evolved to transform themselves for life in saltwater at a particular time or stage of development. Slower migration to the sea also exposes young salmon to more predators. By slowing down water and creating large lakes, dams can also cause the water temperature in the river to rise, which can be fatal to fish. The way dams are managed sometimes creates conditions where there isn't enough water in the river to support fish, and, at other times, so much water is released at such high velocity that it sweeps fish out of the river before they are ready.