When salmon and steelhead don't get the cold water they need, it costs them more energy to survive. Their reproductive success can be diminished and they become more vulnerable to disease.
“And in the worst case, when water temperatures get too high, it can lead to death,” says Joseph Bogaard, executive director of the Seattle-based nonprofit Save Our wild Salmon Coalition.
That’s what happened in the hot summer of 2015, when temperatures all over the Northwest spiked and about 250,000 adult sockeye died in the Columbia River Basin.
Many scientists refer to that year as a dress rehearsal for climate change. Bogaard says that's why they started highlighting the issue with their weekly "Hot Water Reports," which track the temperatures in all eight reservoirs of the Lower Snake and Columbia Rivers, using the federal government's own data on the dams in that system.
The clear trend is rising water temperatures and falling returns of endangered salmon. Bogaard says the water temperatures routinely rise above 68 degrees.
“Hot water – outside of the ‘comfort zone,’ if you will, of cold water fish like salmon and steelhead – is now routine in the Lower Columbia and Lower Snake River reservoirs, for weeks and often months at a time in the summer months,” Bogaard said.
Bogaard says that 2015 dress rehearsal scientists refer to will only get worse.
“Those kinds of conditions are unusual, but they’re becoming more common and they’re going to become more frequent as we move forward.”
He says the Environmental Protection Agency has a model showing dam removal and restoration of the rivers would bring the temperatures down on all but a few days a year. But after 20 years of planning, no federal agencies have taken that advice. Conservation groups sued and last October, a judge ordered the EPA to take action, citing the hot water as a violation of the Clean Water Act. That decision is on appeal. Oral arguments take place in Seattle' s 9th Circuit on Aug. 26.
Advocates say dam removal is the only real option to keep endangered fish from going extinct. Many communities near the dams disagree and are concerned about economic impacts if they're taken down.
Save Our Wild Salmon is pressing the governors and members of congress from Washington, Oregon and Idaho to find ways to take action.