Dams: One Structure, Many Benefits

Managing Flood Risk & Protecting Communities

During years with rapid snowmelt or extreme rains, river flows can damage and even destroy surrounding areas. An example of that destructive power is the Vanport Flood of 1948. The Columbia River rose to more than 23 feet above flood stage, and the levees failed. The flood killed at least 15 people, destroyed the homes of 18,000 residents, and wiped out the then-second largest city in Oregon.

The Vanport Flood spurred development of flood control at Columbia River Basin dams, with a levee system holding back water and releasing it over time. Dams can store up to 40 million acre-feet of water in reservoirs—big artificial lakes.

Engineers operating the dams control how much water gets past the structures using outlets such as hydroelectric generators or spillways. To ensure adequate storage space, engineers draw down reservoirs by letting more water pass through the dams in the winter. This allows large amounts of rain and spring runoff to refill reservoirs.

Irrigating Farmland & Hydrating The Basin’s Bounties

Harnessing river water for growing Northwest crops began more than 200 years ago,  with large-scale irrigation projects taking shape by the mid-1800s. Northwest farmers depend on dams to channel water through a system of pipes, tunnels and canals to irrigate fields that flourish with fruits, vegetables, and large crops of hay and grain that feed the world.

6% of the Columbia River Basin’s yearly runoff is used to irrigate more than 5 million acres of Northwest farmland, mostly in southern Idaho, eastern Washington and eastern Oregon.

Enabling Safe Travel Along Aquatic Super-Highways

Eight federal dams with a series of reservoirs and navigation locks make it easy and safer for vessels moving upstream or downstream. Locks are gated passageways that work much like elevators. They fill up or drain water through valves to lift or lower watercraft. Without the dams, the river would be a series of turbulent rapids and navigation would be more difficult and hazardous.

Barges transport more than 50 million tons of cargo each year between the Pacific Ocean and Lewiston, Idaho, including 60% of the nation’s wheat exports. Using rivers for shipping is highly fuel-efficient. One barge carrying 3,500 pounds of cargo on the river replaces 134 trucks on the road. A towboat pushing four barges that carry 14,000 pounds removes 538 trucks from the road.

Providing Places to Play & Educational Opportunities

The areas behind and around Columbia River Basin dams are popular public sites for all sorts of fun activities. Visitors use reservoirs to enjoy water-based activities, ranging from boating and fishing to windsurfing and kiteboarding. The land near the dams also offers recreational space for camping, hiking, horseback riding, and wildlife viewing.

Some dams—such as Bonneville, The Dalles, and Grand Coulee—offer visitor centers where guests can learn about dam operations, take tours and visit fish viewing windows.

Fueling the Northwest With Clean, Carbon-Free Electricity

Hydropower is a renewable energy resource created by the energy of falling water. Gravity forces water to flow through specially equipped dams to produce carbon-free and inexpensive electricity that fuels the Northwest with nearly 90% of its renewable energy.

In 2020, the 31 Federal Columbia River Power System dams in the Pacific Northwest generated 7,482 average annual megawatts. At full capacity, they can generate up to 22,442 megawatts—enough to power up to 10 Seattle-sized cities.

Because dams do not produce carbon emissions when generating electricity, the abundance of hydropower makes the region’s power system the cleanest in the United States and prevents 50 million metric tons of carbon emissions from entering the atmosphere.