The Columbia River is currently 71 degrees Fahrenheit (21.7 degrees Celsius). That’s 3 degrees Fahrenheit (1.7 degrees Celsius) above levels that are safe for salmon and other cold water-loving animals. Climate change made the heat wave in the region more intense, but other human activities are also behind the salmon’s suffering. Dams up and down the Columbia and Snake Rivers have also left water dangerously hot for the fish. Undammed rivers tend to stay cooler thanks to rapidly moving and churning water. Dammed rivers, though, suffer from stagnant water trapped in reservoirs with large surface areas and stagnant water that can warm more rapidly. Unfortunately, this summer has seen low water levels and freakishly hot air temperatures combine with deleterious impacts in the Columbia River basin.
The watershed hosts numerous salmon and steelhead runs, including at least a half dozen that are endangered or threatened by too-hot rivers. The fish are also important to the livelihoods and traditions of Indigenous tribes throughout the region. Just last year, Washington and Oregon asserted their rights under the Clean Water Act to have waterways free of temperature pollution. Those rights mean the federal government—which operates dams on the Columbia and Snake Rivers—would need to keep temperatures from getting too warm. Columbia Riverkeeper and other groups have also sued over issues around the river, which is what led the Environmental Protection Agency to set a temperature threshold in the first place.
“It’s an ongoing problem,“’ Johnson said. “When you get these really hot cycles, it just kind of pushes the whole system over this threshold.”
But this isn’t solely a problem in one river basin. A similar scenario is also unfolding on the Sacramento River in California, where officials expect “nearly all” juvenile salmon could die this summer due to extreme heat and low water flow tied to reservoir management. State officials also undertook an audacious plan to truck 17 million salmon hatchlings from the Central Valley to sea rather than leave them to navigate the hot, low waterways. Nor is the issue solely relegated to salmon; an estimated 1 billion sea creatures were cooked alive in the Pacific Northwest heat wave alone.
“As we see river temperatures warm, fish might have less access to those types of habitats that they would be seeking out,” Alison Colotelo, a fisheries biologist at Pacific Northwest National Laboratory, told Oregon Public Broadcasting at the start of the heat wave last month. “That’s the risk, is that everything is warming up, and they’re not going to find those nice, cool places where they can hang out and do their thing.”
These problems aren’t going away either. Climate change will keep cranking up temperatures and increasing the odds of drought. A study released just this week showed that “record-shattering extremes” could become up to seven times more likely in the next three decades alone while other research has shown the West is in its worst drought in at least 1,200 years. Even other factors tied to climate change like large, destructive wildfires could create issues for salmon by burning down trees that normally keep streams cool. (They could also dump pollution into waterways, compounding an already compounded problem.) What that means is that water managers will need to figure out how to adapt the current system we already have to buy time and start building a new one at the same time.
Right now, Johnson said, the government could lower reservoir levels so that there’s less surface area to heat up. But that would impede other uses, such as hydropower or providing grain barge access. Longer-term, the government could also rip out the dams so that cold water flows freely, something Johnson said would help the fish thrive again.
“If they don’t get the Snake River back,” Johnson said, referring to the salmon, “they’re going to go extinct. They can’t handle the impacts of the dams and climate change together.