Hydroelectric dams in the Northwest provide some of the cleanest and most reliable electricity in the country. There’s a lot to know about this time-tested technology that has powered homes and businesses for generations.
Most of the power Northwest electric cooperatives and public power utilities buy from Bonneville Power Administration comes from hydroelectric dams.
“[Hydropower] is the foundation of our affordable energy resources,” says Clark Mather, executive director of Northwest RiverPartners, a nonprofit representing Northwest community-owned electric utilities.
Eight dams in the lower Snake and Columbia rivers—especially the four lower Snake River dams—have been the subject of much debate in recent years.
Let’s explore the myths and facts surrounding these power generation systems.
Myth: Hydropower dams in the lower Snake and Columbia rivers are aging and will soon require major investments to maintain.
Fact: The lower Snake and Columbia river dams receive consistent maintenance and investment like any other piece of infrastructure, according to the U.S. Army Corps of Engineers’ Northwestern Division, which operates locks, dams and hydropower facilities along the Columbia River.
“The main components of these structures have held up extremely well,” says Tom Conning, U.S. Army Corps of Engineers’ Northwestern Division public affairs specialist. “However, other items—controls, turbines, etc.—wear out over time, just like parts for a car. We are constantly making improvements that help us balance the various needs that each dam supports.”
Another misconception, he says, is that dams have 50-year lifespans. Dams last far longer than 50 years because they are continually maintained and updated.
The four lower Snake River dams provide some of the lowest cost electricity generation in the federal system, Bonneville Power Administration Senior Spokesperson Doug Johnson says. While major investments in these four dams eventually will be needed, the timing and priority are influenced by asset condition and risk. Current forecasts identify major equipment replacement in the mid-to-late 2030s, BPA says.
Myth: Most hydroelectric power generated in the Northwest is sold to California.
Fact: Most of BPA’s power is sold to Pacific Northwest utilities, Doug says. BPA has designated more than 6,900 megawatts of federal generation to the approximately 140 consumer-owned utilities in the Northwest that it is statutorily obligated to serve. When BPA has surplus electricity, it must first offer it to other utilities in the Pacific Northwest.
BPA sells surplus generation to California and other parts of the Western Interconnection, the electric grid that covers 11 Western states, two Canadian provinces and a portion of Baja California, Mexico.
Buying power from and selling power to California is mutually beneficial, Clark says. It enables states to rely on each other in times of extreme demand—such as during heat waves or cold spells—that could otherwise cause energy shortages.
Myth: The system of locks on the Columbia and Snake rivers is only important to wheat farmers, who could
use railroads or trucks instead.
Fact: It’s true the Columbia and Snake rivers are the largest wheat export gateways in the United States. But the
360-mile inland navigation system through locks at eight dams from Portland, Oregon, to Lewiston, Idaho, is vital to many businesses in the region and is an efficient form of transport.
Last year, barges moved more than 7.3 million tons of cargo through the rivers’ lock system, says Pacific Northwest Waterways Association Executive Director Neil Maunu.
In addition to wheat, barges move renewable diesel, logs, wood chips, finished paper products, corn, soy, gravel, wind energy components, salmon, scrap steel, jet fuel, gasoline, containers, solid waste and other goods.
The average four-barge tow—one boat pushing four barges—can haul more than 14,000 tons of wheat. The same job would require 538 semi-trucks. In 2020, it would have taken 42,160 rail cars or 162,153 semi-trucks to move the cargo that was barged on the Snake River alone.
Barge transportation is a relatively low source of greenhouse gas emissions per mile-ton of freight compared to using trucks or trains, according to a 2020 environmental impact statement on Columbia River System operations. Without using barges, transportation-related emissions for wheat would increase by up to 53%.
Myth: The Columbia and Snake River dams block salmon from migrating upstream and downstream.
Fact: Each individual federal dam within the Columbia and lower Snake River system has effective upstream and downstream fish passage systems, Tom says.
Since the dams were built, the agency has significantly improved downstream migration for juvenile fish, often by spilling water—and young salmon—over the tops of the dams.
Adult passage, meanwhile, is quite high. The U.S. Army Corps built the four lower Columbia and the four lower Snake River dams with fish ladders to help salmon and steelhead safely and effectively migrate upstream.
Improvements continue to be made, including keeping water in the fish ladders cool and enhancing juvenile fish passage.
In 2024, almost 1.8 million adult salmon and steelhead passed Bonneville Dam—the first Columbia River dam encountered in their upstream migration. This is the highest total return in nine years, and the fourth highest since the dam was built in 1938.
After passing Bonneville Dam, some fish are caught by anglers, eaten by predators or travel into tributaries. Many others continue their journeys upstream.
In 2024, more than 530,000 salmon and steelhead passed nine dams on the mainstem Columbia River, and more than 209,000 passed eight dams to reach tributaries, spawning areas or hatcheries where they produce offspring for future generations.
Myth: The lower Snake River dams can be replaced by wind and solar power without significant costs to energy consumers.
Fact: Hydropower is an always-available energy source. Replacing all of the generation with other renewable energy sources would raise costs and lower reliability.
Wind and solar energy are intermittent sources of generation. They don’t produce power when the wind isn’t blowing or the sun isn’t shining. On top of the cost of building new wind and solar generation to replace existing power sources is the cost of additional backup generation.
Benton County PUD General Manager Rick Dunn, who writes about the clean energy transition on Substack, says wind and solar generation rely on large amounts of minerals, such as copper. Large-scale mining activities are needed to support the growth in wind and solar, he says.
Energy and Environmental Economics, an energy consulting firm, found that replacing the four lower Snake River dams with a combination of wind, solar, battery storage and one emerging technology—such as longer lasting batteries—would increase BPA’s wholesale power rates 8% to 18%, or $100 to $230 a year per end-use ratepayer. If the energy produced by the dams was replaced with energy from just wind, solar and battery storage, the increase would be 34% to 65%, or $450 to $850 a year per end-use ratepayer.
Replacement resources—if they include one new technology—could cost $11.2 billion to $19.6 billion. Those costs increase to between $42 billion and $77 billion if no new combustion generation resources are used.
Hydropower generation is a major benefit to people who live in the Northwest. Dams bring many other benefits to the region, including flood control, irrigation water, river transportation and recreation.
By understanding the facts, energy consumers remain informed about the systems in place to maintain, improve and protect the region’s renewable and reliable energy resources.
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