More than 100 years ago, Idaho settlers realized they could take water from the Snake River and pump it across their land to grow crops. Before long, the federal government started building dams that slowed down the river enough to store water for irrigators in giant lakes. Congress even created a government agency to help pioneers settle the desert West and gave it lots of money. Today, the river passes more than a dozen major dams, including four between Pasco and Lewiston. Besides providing irrigation water, the dams turn the power of falling water into electricity that lights homes for hundreds of miles around.
Some dams do another important job for people who live in the Snake's wide valley.
They control floods by storing water and releasing it slowly. In the spring, the Snake can be so full of water that it's fast and very dangerous. Because of that, early explorers called it the Mad River. Dams also make lakes where thousands of migrating birds stop for a rest on their long flights. But there is a problem with dams - and some people want to take out the four on the lower Snake River to make life easier for fish.