WASHINGTON — When President Dwight Eisenhower signed the Columbia River Treaty with Canada as one of his last official acts in January of 1961, global warming did not rank as a public concern.

Fifty-two years later, it's a far different story: Scientific models predict that rising temperatures will reduce the snowpack and glacier mass in nearby mountains, resulting in less water during seasonal runoffs for the 1,243-mile-long Columbia River, the longest in the Pacific Northwest.

The treaty created a massive system of dams for flood control and electricity for the Northwest, but changing weather now might mean fewer fish and might damage the river's ability to feed the turbines that have produced billions of dollars' worth of hydropower for the two nations.

Consequently, environmentalists want climate change to take center stage as U.S. and Canadian officials try to decide whether to extend or change the treaty.

Either party may end the agreement on Sept. 16, 2024, with a 10-year notice, which has both sides scrambling to figure out what to do by next year.

The treaty came as a response to a 1948 flood that, Katrina-like, destroyed the small city of Vanport, Ore. Critics say the pact has been a force of destruction for the environment, killing off many endangered species. Thirteen different stocks of Columbia River salmon and steelhead are on the list of threatened and endangered species, while dozens more are extinct.

Indian tribes are particularly unhappy, saying the dams made it impossible for salmon to navigate the river, once home to the largest salmon runs in the world. And they're upset that they weren't allowed to participate in the original treaty talks.

"I'm pretty sure the tribes would universally say it's been pretty bad," said Paul Lumley, the executive director of the Columbia River Inter-Tribal Fish Commission in Portland, Ore., and a member of the Yakama Nation in central Washington state. "It changed the way the river flowed and impacted salmon passage, and it was just a pretty bad deal for the tribes. And the tribes were completely ignored — that's a true statement."

This time around, Lumley said, tribes are making sure their voices are heard: "We've fought hard to have a seat at the table." But even though tribes have been unable to take full advantage of the fishing rights promised to them in treaties with the U.S. government, he said tribes weren't "angling for compensation" as part of the treaty talks.

Rachael Paschal Osborn, an attorney with the Center for Environmental Law and Policy in Spokane, said historical records made it clear that planners knew the dams would hurt salmon but decided to proceed anyway.

"It has done incredible damage to the ecosystem," she said, adding that allowing salmon to once again pass through the Columbia should be a key focus of the talks. She also said officials must decide what to do about tribal villages and graveyards that were inundated by reservoirs and might be uncovered in the event of a major drawdown.

"It's an important issue. It's a cultural issue," Osborn said.

Congress set the stage for the treaty by passing the Flood Control Act of 1950 two years after the monster 20-day flood hammered Vanport, a city of 18,000 near Portland. The Grand Coulee Dam had been built in Washington state in 1941, but the flood made it clear that the dam wasn't enough to stop flooding on the wild Columbia. So more dams were built.

After the treaty was ratified in 1964, a flurry of construction followed.

For starters, the United States paid Canada $64 million for 60 years of flood protection, helping to build three new major dams.

A group of U.S. utilities agreed to give $254 million to Canada as a fixed payment for half the electricity produced downstream during the first 30 years of the agreement.

In 1994, the United States began paying a yearly amount that fluctuates based on market prices, and those payments now range from $250 million to $300 million per year, according to the Bonneville Power Administration, which harnesses the river's energy and oversees the treaty for the U.S. along with the Army Corps of Engineers.

The Columbia River begins as a small stream in the mountains of Canada before entering Lake Roosevelt at the U.S.-Canadian border, then making its way through 11 dams and reservoirs before discharging into the Pacific Ocean near Astoria, Ore.

The entire river basin is home to 274 hydroelectric dams, making the Columbia one of the most hydroelectrically developed rivers in the world.

The Bonneville Power Administration has been happy with the results.

"This Columbia River Treaty has been a model of international water relations, and it has worked very well for both sides," said Michael Hansen, a spokesman for the power administration.

With the river already so developed, Osborn said, there's little choice but to extend the treaty so that the two nations continue to coordinate on how to operate the dams. She said there was plenty of "pre-positioning" going on in the Northwest, with various agencies trying to figure out ways to get more water from the Columbia before any new restrictions take effect. The river is a prime source of water for farmers in Washington state.

Osborn said that if environmental issues didn't receive top billing during the new treaty talks, they should at least receive equal treatment with hydropower and flood control.

"I mean, let's face it: Flood control is necessarily always going to be a priority under the treaty," Osborn said.

Rob Hotakainen covers Washington state from McClatchy's Washington, D.C., bureau. Reach him at rhotakainen@mcclatchydc.com.