High Water Temps Killing Fish in the Columbia River
by Cole Goodwin
High water temperatures are killing fish in the Columbia River Gorge this month.
Several entities, including Columbia Riverkeeper said that water in the Columbia and Snake Rivers had become “superheated” due to a combination of climate change, heatwave events, and overheating problems related to stagnant dam reservoirs.
Temperatures in the Columbia River currently exceed 71 degrees Fahrenheit.
This was the read out today, July 29, taken from the US Geological Survey website.
The optimal temperature for salmon and fish to thrive sits between 44 and 67 degrees F.
"Sockeye are dying right now because the Columbia and Snake rivers are too hot,” said Brett VandenHeuvel, Executive Director, Columbia Riverkeeper. “I’m hopeful this tragedy will inspire our elected leaders to take action to restore our rivers before it is too late."
Sockeye salmon with lesions, Little White Salmon River, July 16th, 2021 photo by Conrad Gowell.
Migrating Salmon Hiding Out in Cold Water Refuges
Columbia River Inter-Tribal Fishing Commission said that the rise in river temperatures had created a dire situation for the Sockeye salmon in particular and that many fish were hiding out in cold water refuge areas.
“The water is colder at the mouth of the White Salmon River, so many of the fish are currently taking refuge there,” said Jeremy FiveCrows spokesperson for Columbia Inter-Tribal Fish Commission.
Restoration efforts of salmon’s traditional spawning streams might prove fruitless if Columbia River temperatures continue on an upward trend, FiveCrows said. If water temperatures increase many salmon may not continue on their journey upstream to spawn and reproduce.
According to Columbia Riverkeeper “Adult salmon have difficulty migrating upstream when water temperatures approach 68 °F. Migration stops altogether when water temperatures reach 72 to 73 °F. Salmon that have stopped or slowed their migration, and languish for days or weeks in warm water, begin dying from stress and disease.”
“ “CRITFC is dismayed by the conditions that fish are encountering in the Columbia River. The tribes and others have been raising the alarm that the region must address the many threats salmon face; threats that are increasing in both number and severity as climate impacts grow,” said Aja DeCoteau, Interim Executive Director of Columbia River Inter-Tribal Fish Commission.
“Even in good water years, salmon struggle to migrate up and down this heavily altered river system. This is not what these salmon are evolved for and they are hanging by a thread. The low flow from the drought and high water temperatures from extreme heat events is too much for these fish to bear. The region must use everything we have in our dam operations toolbox to do what we can to lower river temperatures and increase flow. It is also imperative we explore all options available to address the impacts of climate change; impacts that are exacerbated by the reservoir system humans created. The region needs to do this now to ensure future generations can enjoy salmon. Listen to what the fish are telling us,” said DeCoteau.
Rising River Temperatures Threaten Aquatic Life
Trends show that the Columbia River has been experiencing an upward trend in water temperature.
“Water temperatures passed into the stressful zone on June 27th, nearly one month earlier than average,” said Jeremy FiveCrows spokesperson for Columbia Inter-Tribal Fish Commission.
Higher temperatures mean less oxygen in the water and a better growing environment for fungal infections in fish that can grow into large lesions and eventually kill the fish. Columbia RiverKeeper released a video showing several fish in the Little White Salmon River suffering from heat stress-related lesions earlier this week.
CCC News also took video of a fish in Mill Creek in The Dalles, suffering from heat related lesions during the June heatwave.
The lesions seen in both videos is a result of saprolegnia mould.
“Saprolegnia mould shows as a white or grey patch on salmon. It grows faster at higher temperatures, up to 25C (77F). It tends to affect injured or stressed fish. It can lead to mass mortality,” said David Denning, Professor of Fungal and Infectious Diseases at The University of Manchester. “The role of temperature shifts in salmon survival is not well worked out, and other factors such as extensive use of antibiotics in salmon hatcheries may increase fungal disease.”
An image showing a dead fish with heat related lesions floating in Mill Creek in The Dalles, OR.
Water that is too hot is generally dangerous for many types of aquatic life. High water temperatures within the 75-80 range can cause many aquatic organisms, including fish, to suffocate, because, again, there is not enough oxygen in the water.
Fish are cold-blooded organisms, and the temperature of their environment has a dramatic impact on their thermoregulation, behavior, and health. Adult fish generally have a higher heat tolerance than younger fish, although both are still sensitive to rising water temperatures. Of the many fish in the Columbia River region, salmon and trout, in particular, prefer colder waters.
“Imagine the heat that we’re feeling. They’re feeling it ten times worse in that river,” said Don Sampson of the Northwest Tribal Salmon Alliance, “They’re suffocating. They’re weakened.”
Sampson said that the sockeye salmon are currently returning from the ocean where they’ve spent a few years building up their strength so that they can return to their natal streams to spawn.
Unfortunately, sockeye salmon are more sensitive to heat fluctuations than other kinds of salmon such as Chinook.
“One bright spot for this year compared to 2015 is that the heat came a little bit later,” said FiveCrows. “Sockeye are very susceptible to the heat. The Chinook have a lot more thermal tolerance, but the sockeye is not as capable of handling it. Ninety percent of the sockeye destined for Idaho died in the Columbia River in 2015.”
A graph from Columbia River Inter-Tribal Fish Commission showing rising water temperature trends in the Columbia River Gorge. Source.
Sockeye Salmon Nearing Quasi-Extinction
Forty-two percent of the sockeye salmon have already passed the quasi-extinction threshold. Meaning that forty-two percent of streams saw fewer than fifty adult salmon return to their natal streams to spawn. And a study by the Nez Pearce tribe scientists predicts that seventy-seven percent of sockeye will reach their quasi-extinction threshold four years from now in 2025.
A graph comparing this years Bonneville Dam fish counts with last years counts and a ten year average. Source.
“The reservoirs these dams create are just stagnant cesspools that are heating up and killing them,” said Sampson. “We’re in a salmon crisis, and it’s time for Congress to act.”
“We are losing so much more than a fish,” said Giulia Good Stefani, a senior attorney with NRDC. “Salmon support a way of life for both native and non-native rural communities from the coast to the Northern Rockies. The reservoirs behind the four lower Snake River dams are reaching deadly temperatures, and the time to take action, both ecologically and politically, is right now.”
Vigil Planned for Sockeye Salmon
Columbia Riverkeeper will be hosting a vigil for the sockeye salmon currently suffering and dying from hot water on Friday, July 30th, from 12 p.m to 1 p.m at the Little White Salmon National Fish Hatchery in Cook, Washington.
Sign Up here to join in person or to participate in the vigil online.
Working to Lower River Temperature
Earlier this week the U.S. Army Corps of Engineers started releases of 43 degrees F water from the large reservoir behind Dworshak Dam in Northern Idaho to try and cool temperatures in the Snake River.
“Dworshak Dam is kind of like the refrigerator of the system,” said FiveCrows.
“Water managers have been closely working with regional partners to explore the effects of numerous alternatives to support extending the cold water releases from Dworshak Dam as far into the summer as possible," said Matt Rabe, Public Affairs Director at the Army Corps of Engineers.
Dworshak Dam in Northern Idaho, 40 miles North of Lewiston, Idaho.
“It's much too early to say we are "out of the woods" yet, but with current temps and actively moving sockeye combined with IDF&G transporting adults now, the situation is not nearly as dire as it was about this time in July in 2015. We will continue to take this developing situation one day at a time and continue our close coordination with NOAA and the other Action Agencies regarding operations at our dams for fish,” said Rabe.
While this may be good for the Snake River, water managers said that Dworshak Dam water releases are not likely to influence water temperatures in the Columbia River.
Army Corps of Engineers Officials said that they have not altered their operations due to the heat and that The Dalles Dam does not have Dworshak Dam’s same ability to control temperature by spilling water as the reservoir behind it is not high enough or deep enough for there to be significant temperature differences in different levels of the water reserve. Other dams have in the past altered their summer spills in an effort to lower river temperatures.
