EDITOR’S NOTE: This story is an excerpted reprint of a 2024 series in Rural Montana magazine. You can read the full series at mtco-ops.com/rural-montana.)

Over the past 18 months, the Lower Snake River dams in southeast Washington state have been the focus of intense political attention as the industry reacted in late 2023 to word of a secret Biden administration agreement that envisioned the eventual breaching of the dams.

A subsequent public memorandum of understanding, signed by the Biden administration, environmental and tribal groups and the states of Washington and Oregon, followed. It requires decreased generation output of the dams, ostensibly to protect endangered fish. A related Department of Energy study on replacing the power and services of the dams escalated the regional and national response.

NRECA sent strongly worded letters to the Biden administration and Capitol Hill, and Matheson testified before the House Energy and Commerce Subcommittee on Energy, Climate and Grid Security warning that breaching the dams would threaten the region's power supply as demand is skyrocketing and would hurt farmers and economically disadvantaged rural communities. NRECA's grassroots network, Voices for Cooperative Power, collected nearly 20,000 signatures in opposition to the Columbia Basin Restoration Initiative. And in a letter to President Donald Trump in December, Matheson pressed Trump to reverse “the harmful plan to continuously attack, and eventually remove" the dams.

What the Trump administration does with the agreement is yet to be seen. And it would take an act of Congress to actually breach the dams. But NRECA and co-ops in the Northwest say they'll remain vigilant and continue to fight any efforts to do away with these critical resources.

“NRECA has no greater mission than fighting back against government rules and regulations that will hurt power reliability and ultimately harm co-op members," says Louis Finkel, NRECA senior vice president for Government Relations. “Preserving the Lower Snake River dams is among our top priorities."

What follows is a comprehensive look by Rural Montana magazine at the critical functions and impacts of the Lower Snake River dams on Northwest communities.

Hydropower

The Lower Snake River dams comprise Ice Harbor, Lower Monumental, Little Goose and Lower Granite. Each facility has six turbines and varies slightly in age, style and output. Combined, the four dams are capable of producing enough electricity to power all of Montana and Wyoming, according to Paul Ocker, chief of operations and maintenance for the Walla Walla District of the Army Corps of Engineers, which manages the dams.

Ocker says the mission of the dams has changed since they were built in the 1960s and '70s. Their main purpose was for navigation, and hydropower was added later. All four dams were built with fish ladders for returning adult fish, and additional passage measures for juveniles were added later.

Ocker says that in his 24 years with the Army Corps of Engineers, power has taken a back seat to fish considerations. In 2022, the Lower Snake River dams produced 6.6 million megawatt-hours of power—less than it used to be and far less than it could be.

“We are spilling a lot of water for fish migration," Ocker says.

In the past, each of the Lower Snake River dams would typically run five turbines. In spring of 2023, with low flows and a new court settlement and biological opinion dictating spillage, the dams typically ran one turbine and often at minimum generation.

“A lot of things we are doing differently are related to that biological opinion," says Rob Lustig, operation project manager at Lower Granite Dam. “Here, hydro is not king."

“Normally this time of year, we had three, four, five, even six turbines running at up to max output," Lustig says.

Prior to the settlement agreement, a biological opinion issued by the National Oceanic and Atmospheric Administration would dictate how much the dams could generate.

“We spilled excess water if there was not enough demand," Ocker says. “Now, we spill specifically for fish eight or nine months out of the year. As the Corps of Engineers, what we are required to do is balance what the people need and what the environment needs."

One key element, even with the fish passage plan, biological opinions and court settlement, is hydropower's ability to respond to a power emergency where demand outpaces supply.

“There's still the availability component. That availability is still important to the reliability of the grid," says Harold Wentworth, chief of operations for Ice Harbor. “If an emergency were to happen, we would deviate from the fish passage plan with appropriate coordination."

He says that if the Bonneville Power Administration were to call for more power, which could occur if intermittent generators such as wind or solar were to stop producing, there has to be backup power that is already spinning and ready to ramp up.

“Our projects fill that gap," Lustig says.

Ice Harbor dam is capable of producing an additional 100 MW in two to three minutes and can be at full power within eight minutes, Wentworth says. The same is true up and down the Snake River, including at Lower Granite dam.

“In six minutes," Lustig says, “we can go from not generating anything to powering a city the size of Portland."

Salmon and steelhead

Protecting adult salmon has been a consideration at the Lower Snake River dams since they were built, with a fish ladder included in each project. The ladders see thousands of fish daily during peak runs, while juveniles are bypassed around dams, and spillage and turbine use are balanced to protect young and adult fish. Thousands of fish each season are also researched and studied at the dams.

As the first dam juvenile fish encounter on the Lower Snake River and the last dam adults encounter, Lower Granite is home to more than a dozen research projects during fish runs. NOAA, Idaho Fish and Game, the Nez Perce Tribe, the United States Geological Survey and others send researchers to the dam's multiple research facilities. Adult and juvenile fish are measured, weighed and tagged in hopes of better understanding the dams' impact on their numbers and how mitigation measures are working.

Ocker with the Army Corps of Engineers says the emphasis has shifted more to juvenile fish, especially in light of the recent NOAA biological opinions and court settlement.

“It is the desire of the environmental groups and the plaintiffs to have all juvenile fish pass by a non-powerhouse route," Ocker says.

There are several ways for juvenile fish to avoid the powerhouse, including being diverted by fish screens to a bypass channel. A majority of the diverted fish are then barged downriver to avoid passing any other dam downstream.

The Army Corps of Engineers barges millions of fish each year, beginning at Lower Granite and dropping off below Bonneville Dam. Throughout the journey, fresh water from the river is pumped through the holding tank so fish can still “olfactory imprint" to the river to be able to find their way back as adults. The survival rate for barged fish is about 98%.

Two main elements of the recent settlement agreement are that spillage comes before power during the salmon runs, and that maximum spillage is based on the total dissolved gas (TDG) generated in the river as a result of the dams. Too much TDG can lead to gas bubble disease in fish and cause formation of bubbles in the fins, eyes, gills and cardiovascular system.

Another concern with fish utilizing the spillway is the pressure change it introduces. Most salmon prefer to be in the top 20 feet of the water column, but the traditional spillway gates are 53 to 57 feet below the surface. This forces fish to swim to those depths, at pressures of up to 25 pounds per square inch. Once they swim through the gate, they exit the dam down the spillway and come out in the river below, nearly instantaneously going to zero pressure.

That can have negative impacts on the fish, Lustig says. Those fish can become disoriented and rise to the top of the water column, increasing the likelihood of predation by other fish or birds, such as pelicans.

Predatory birds, except for endangered raptors, are hazed from the immediate area of the dams by water cannons, sounds of gunshots played over speakers and wires stretched across the river.

Fish that pass through the removable spillway weir (RSW) do not experience much pressure change, but that gate is much more expensive and is incapable of allowing higher flows of water through the dam in its normal configuration. During high-flow flood events, the RSW is designed to be removed until the event is over.

Ocker says that returning fish numbers have gone up and down for decades. The numbers are determined by a person sitting at a window looking into the fish ladder and physically counting them and identifying the species.

“Most fish die in the ocean," Peery says, noting that salmon population numbers can be linked to ocean temperatures and other conditions. “They tend to fluctuate."

Another concern is ocean fishing, which is essentially unregulated more than 200 miles from shore, according to Peery.

“It's a free-for-all out there. Some nations fish 12 months a year, 24/7," Peery says. “For all the efforts on the river trying to produce more salmon, a lot of that is just going out to subsidize ocean fishing."

He says some environmental groups claim that taking out the dams would increase salmon populations by 150%, but a NOAA study showed the expected improvement would be just 14% in adult returns.

Navigation

The four Lower Snake River dams may now be most known for producing clean, affordable and reliable power and for their fish-mitigation measures. But when they were built, establishing a navigable channel for shipping barges was the primary goal, and that function remains key today.

The dams serve the most inland seaport in the Pacific Northwest allowing ocean access, the Port of Lewiston in Idaho. Without the system of dams and locks, the river would not be navigable for barges and ships. Ocker says the dams help maintain a 14-foot deep navigation channel on the Lower Snake River.

“We truly have a global impact," Ocker says.

A majority of the lockages performed at the dams are for barges, though recreational lockages are also common. In recent years, cruise ships have become popular on the Snake River as well.

The locks allow boats and barges to safely navigate the 400-foot change in water elevation from the first of the four dams to the last. Each lock is 666 feet long and 86 feet wide and holds about 43 million gallons of water.

A barge traveling downstream pulls into the lock, the doors close behind it, and water is spilled out of the lock until the water level matches the downstream level, at which point the doors open and the barge continues its journey. When traveling upstream, the process works in reverse. Times vary by lock style, but the process typically takes less than 20 minutes.

Agriculture and recreation

The Snake River dams play a vital role in recreation and environmental stewardship in the Northwest and have important impacts on irrigated farmland.

“Whenever you build a dam, you have a bunch of associated missions that go along with that," says Chad Rhynard, chief of the technical support branch for the Army Corps of Engineers' Walla Walla District. He says the Corps oversees Habitat Management Units (HMUs), lands preserved specifically for recapturing native habitats.

“We have a lot of cultural significance along our shorelines," he says. “It's where your grandfather took you fishing for years growing up. ... We're trying to manage native landscapes the best we can."

He says that the dams present unique recreational opportunities, with areas upstream of each dam looking more like a lake, while downstream areas have more of a river feel. In addition to the parks and campgrounds, the HMUs the Corps manages are valuable for recreation and wildlife.

“Without the dams, those opportunities would be lost," says Brandon Frazier, assistant natural resource manager for the Army Corps of Engineers. “A lot of those riparian areas would be dry."

Agricultural irrigation is not one of the core missions for the Lower Snake River dams, but they still play a vital role for regional farmland.

Ocker says there are about 48,000 acres of irrigated lands as a result of Ice Harbor Dam. Apples, cherries, grapes, wheat, canola, mint and more are all aided by irrigation.

A 2022 report, “Lower Snake River Dams: Benefit Replacement Report," notes that the combined production value of irrigated land along the Snake River in 2021 was estimated to be almost $328 million.

The report also states that if Ice Harbor Dam were ever to be breached, the cost estimates for mitigating impacted irrigation from wells and surface water combined would range from $188 million to $787 million. The additional annual maintenance cost would be another $7.4 million. Over 50 years, these annual maintenance costs equate to an additional $218 million, the report states.

Related Content

• Infographic: The Lower Snake River Dams