The Columbia River winds its way through the U.S. states of Washington and Oregon and the Canadian province of British Columbia.

The river was once full of wild rapids and strong salmon populations.

Now, the 1,954-kilometer (1,214-mile) river is much calmer. Bridges seem to have tamed it, like saddles on horses. More importantly, a series of dams has chopped the once mighty Columbia into a series of peaceful reservoirs. Water passing through the blades of the dams generates power.

The first major artificial change to the Columbia River occurred in 1938 with the completion of the Bonneville Dam. The Bonneville Dam is actually a series of several dams. They link Oregon and Washington. Located in the Columbia River Gorge National Scenic Area, the Bonneville Dam was built for two reasons. One was to provide residents of the Pacific Northwest with electricity. The other was to make the waterway easier for boats to navigate.

Power-Producing Dams

Other dams were built along the course of the Columbia, including the huge Grand Coulee Dam in Washington. It is the largest concrete structure in the United States. Currently, there are 14 major dams on the main stem of the Columbia River.

The dams on the Columbia generate about 50 percent to 65 percent of the area's electricity. They produce that power using less coal and natural gas than other power generators. The dams also make it possible for boats to travel 750 kilometers (465 miles) up the Columbia River, from the Pacific Ocean all the way to Lewiston, Idaho.

Salmon Runs

The dams have made trouble for the river's ecosystem, especially the Columbia's salmon. Jeff Hickman is a former organizer for the Sierra Club, an environmental organization. He says the area was once very healthy. "It had the largest population of fish on the planet," Hickman says.

The Columbia was once a fast-moving waterway, but the dams broke it into a handful of reservoirs with slower currents and warmer water. Hickman says the warmer temperature puts more stress on migrating fish. It also creates a more suitable environment for predators that eat those fish.

The Columbia River Inter-Tribal Fish Commission is an organization that represents the region's Native American population. Bob Heinith is their water program coordinator. According to Heinith, the dams have destroyed fish habitats. He says dams have cut off access to upstream areas, which has destroyed about two-thirds of the overall habitat for fish.

Fish Ladders

Fish ladders were constructed at many of the dams. These allow adult salmon to bypass the dams and continue upstream to lay eggs. The fish ladders are like steps that water flows down. They create a series of shallow waterfalls. Dams are often impossible for fish to pass. The salmon are able to get upstream using these fish ladders, though.

Once the fish are born upstream, they have to head back downstream to the ocean. The Bonneville Power Administration has tried to assist the young fishes' journey downstream in a few ways. The dams' blades have been redesigned so that they are less dangerous to fish passing through. They also added a path that allows the fish to swim around the blades entirely.

A process known as spilling seems to help the fish, too. During salmon migrations, water is spilled over the dams to imitate the river's former flow. The dams generate less power, but this approach is better for the fish.

Sea Lions

Over the last few years, a new problem has emerged.

Sea lions have learned that they can travel from the Pacific Ocean up the Columbia River. At the base of Bonneville Dam, they can feast on the salmon that congregate there. To deal with the problem, the U.S. Army Corps of Engineers and the states of Washington and Oregon scare away the animals with firecrackers and rubber bullets. The states have even begun the questionable process of putting to sleep repeat offenders.

The Sierra Club notes that the Bonneville Power Administration's efforts have yielded some results. They wonder, though, if the dams are worth all the extra time and money.

"There's no doubt it's helping, but you have to weigh out the costs," Hickman says.