Day and night, five turbines hum at the base of Libby Dam. Spun by water from its reservoir, Lake Koocanusa, each one can generate 120 megawatts of power — enough for 87,600 homes.

The dam, run by the U.S. Army Corps of Engineers, is one of four envisioned by the Columbia River Treaty, a 1964 agreement between the United States and Canada. Under this pact, the two nations have tamed the river’s floods and supplied the West with hydropower.

But these gains are now up for debate. The United States and Canada plan to start re-negotiating the treaty this year. Both sides support the treaty in principle, but are at odds over some details. One of these is the power generated at dams like Libby.

“The Columbia River system is operated as one system,” explained Greg Hoffman, Libby’s fishery biologist. The United States and Canada have built dams along the river and its tributaries, which drain a cross-border region the size of France, since the 19th century. After a 1948 flood devastated the town of Vanport, Oregon, the two countries sought ways to better manage the waterways.

These discussions culminated in the Columbia River Treaty of 1964. Canada agreed to build three dams in British Columbia, together able to store 15.5 million acre-feet of water. This step provided 60 years of guaranteed flood control for the United States, which paid Canada $64.4 million.

The treaty also permitted the United States to build Libby Dam across the Kootenai River, which eventually joins the Columbia. The 7.6-million-ton structure can hold back more than 5.8 million acre-feet of water.

These dams flooded valleys and displaced residents on both sides of the border, but also boosted the region’s energy supply. Hydropower now provides more than half of the Northwest’s energy, and regional energy rates are among the lowest in the nation.

Now, the pact guiding this system is set to change. In 2024, six decades after ratification, either signatory will have the right to cancel most of the treaty with 10 years’ notice.

Last December, the State Department announced plans to begin talks on the topic this year (a starting date is still being determined, according to a State Department spokesperson). Both the United States and Canada have voiced their desire to modernize the treaty. But the challenges of this task are becoming clear.

The negotiators will face a region greatly changed since 1964. New infrastructure has been built on both sides of the border, and concerns about ecological health and Native American rights have become part of the policy-making process.

One way or another, most of these issues lead back to electricity.

By regulating water flows, the treaty’s three Canadian dams made existing American dams downriver, in Washington and Oregon, more productive. The United States and Canada agreed to split this added production evenly.

Canada’s share is known as the “Canadian Entitlement,” and is between 1,100 and 1,400 megawatts of generation capacity, worth $120 to $300 million, each year. The Bonneville Power Administration, which retails the dams’ electricity, delivers it to British Columbia through a link between the grids.

Both countries want to change the way this delivery is calculated. And both are citing new developments along the rivers to bolster their cases.

The Treaty’s U.S. Entity, composed of Bonneville and the Army Corps, wants the downstream benefits, and therefore the Entitlement, pared down. A main reason is that, in recent years, a subtle distinction in the treaty has yawned wider.

The agreement defines the treaty dams’ benefits as their added “hydroelectric power capable of being generated in the United States of America.” However, new environmental safeguards have the United States producing below that capability.

In the 1990s, 12 species of Columbia salmon and steelhead were listed as endangered or threatened, requiring federal agencies to protect them. This effort includes periodically opening dams’ spillways, sending fish over the turbines and toward the ocean.

From a power-generation standpoint, that’s wasted water. “We’re not burning it through the turbines and we’re not producing electricity,” explained treaty expert Barbara Cosens, a professor at the University of Idaho College of Law.

In 16 years at Libby, Hoffman has seen these measures in action. “Oftentimes, we’d experience a month of minimum flows” through the turbines, “so it’s a pretty big impact on power generation.”

But this drop isn’t factored into the Entitlement. “What the U.S. would like is [for] the Canadian Entitlement to be based on what we actually end up producing after we actually made all those adjustments to the operation of the system,” Cosens told the Daily Inter Lake.

Fish protection isn’t the only post-1964 shift. Both nations have since added hydropower capacity as well.

The treaty allowed, but did not require, the United States to build Libby Dam. Dedicated in 1975, it spun out $138 million worth of electricity last year, according to its natural resource specialist, Jake Williams.

The treaty stated that Libby benefits would “accrue to the country in which they occur.” Some of those benefits are north of the border. Below the dam, the Kootenai River makes a U-turn and returns to Canada, joining other tributaries and flowing through turbines also added after the treaty ratification.

State Rep. Mike Cuffe, R-Eureka, thinks it’s time to account for those changes.

“One way would be to say [that] we provide flood protection and the ability to generate power right here at Kootenay Canal,” he said, pointing to that station, whose name comes from the river’s Canadian spelling, on a map.

“Maybe British Columbia should pay us a check for flood protection [and] power generation, the same basic idea why the treaty was formed,” he told the Inter Lake.

The province sees things differently. In an email, the B.C. Ministry of Energy, Mines and Petroleum Resources acknowledged that “the benefits of Libby coordination to Canada are reduced flooding at Kootenay Lake and improved power generation on the Kootenay River,” but also noted that “each country retains the benefits of this coordination.”

And while America seeks a slimmer Canadian Entitlement, based on actual power generation rather than capability, British Columbia plans to raise additional factors — including ecological ones — in the coming talks.

“Over the last number of years,” the ministry stated, “the value of the treaty beyond power and flood control has been recognized by more and more U.S. agencies, industry sectors and stakeholders.”

“When we reach out to Americans, we hear how the operation of Canadian treaty reservoirs benefit navigation, salmon population recovery efforts, recreation and water supply ... We have conducted an evaluation of those benefits and this will be discussed at the negotiating table with the U.S.”

As the negotiations approach, the University of Idaho’s Cosens sees international legal norms favoring the American stance, but doesn’t believe an outcome can be predicted.

But whatever that outcome is, it’s likely to affect Flathead Valley residents.

The Bonneville Power Administration, which provides the Canadian Entitlement, is also the sole provider of electricity to the Flathead Electric Cooperative, according to its general manager, Mark Johnson.

He’s closely watching what happens next. “We believe that the resources that are going to Canada exceed the benefits that we’re getting on the Columbia River system,.” he said. “It is important to renegotiate the treaty to make sure that ... we’re paying a fair price for them.”

Flathead Electric belongs to a regional association called the Columbia River Treaty Power Group. On its website, the group argues that “the U.S. currently overpays Canada about 70-90 percent for downstream power benefits from Canadian storage,” an overpayment passed on to ratepayers.

But even the current Entitlement is a small fraction of the Northwest’s power supply.

Last year Bonneville, a federal agency that receives all its funding from power sales, reported $2.98 billion in operating expenses. High estimates of the Canadian Entitlement’s value come in at $300 million.

Citing those numbers, Arne Olson, a senior partner at E3 Energy + Environmental Economics, said that “at most this might be a 10 percent increase or decrease to the [Bonneville] rates that they charge to their utility customers.” Those rates, he continued, are only part of a consumer’s bill.

But even if the dollars-and-cents stake for residents is small, the Canadian Entitlement holds major importance for those running Northwest Montana’s dams and power lines. It’s their measure for an even sharing of benefits as the Columbia River Treaty awaits a 21st century update.

“It’s just a question of fairness,” Johnson said. “The ratepayers in the Northwest fund the Canadian Entitlement.”

“There’s a value for everything, and the fair value is what we want to pay.”

U.S. Columbia River Treaty Negotiator Jill Smail will host a Town Hall on Wednesday, April 25. She and other government representatives will review the upcoming negotiations and their plans for engaging the region, and take questions.

The event will take place at the Historic Davenport Hotel in Spokane from 5-7 p.m. Pacific Time. Those unable to attend in person may participate via phone by calling 1-866-340-4886 and entering the passcode 372778087#. Questions may be sent in advance to ColumbiaRiverTreaty@state.gov.

Reporter Patrick Reilly can be reached at preilly@dailyinterlake.com, or at 758-4407.