Fish face a ‘triple threat’ in the Columbia River: Rising temperatures, stagnant water and toxic algae
By Henry Brannan, Columbian Murrow News Fellow
Published: July 11, 2025, 6:10am
Environmental group Save Our Wild Salmon released its first Columbia River Hot Water Report of the year Wednesday, as water temperatures throughout the basin this year have already surpassed the key 68-degree threshold for salmon health.
The report compiles water-temperature data with a summary of research to highlight the challenges that endangered salmon and steelhead face throughout the Columbia Basin. Its first installment this year comes as Washington is in drought, the already-low snowpack is quickly melting and once-rare toxic algae blooms have already started up for the season.
“The initial signs are another year, like previous years, where we’re going to have extended hot-water episodes in the reservoirs that have been created by the lower Columbia and the Lower Snake River dams,” said Joseph Bogaard, executive director of the group.
Bogaard has been in the role for about a dozen years and at the organization for about three decades. During that time, he’s seen the problem of increasingly warm water worsen.
“Salmon and steelhead and other native fishes in the Columbia Basin today are facing a sort of triple threat that is heat, stagnant waters and toxic algal blooms,” he said.
But the issue is much older than the 10-year-old Hot Water Report. The Great River of the West warmed about 4 degrees between 1853 and 2018, a 2023 study found. The research also noted that the number of days when water temperatures surpassed 68 degrees increased about 12-fold to 60 each year.
That 68-degree threshold is crucial for salmon survival, said Doug Hatch, a scientist who has worked at the Columbia River Inter-Tribal Fishing Commission for 35 years. He was not involved in the report.
“The basic thing to remember is that they’re coldwater fish, salmon,” he said. “If it’s below 68 degrees, it’s not optimal — something closer to 50 degrees would be optimal temperature — but they can survive up to maybe about 72.”
Water temperatures in the 70s have caused salmon to die in recent years.
The Army Corps of Engineers, which runs most of the federal dam system, said it is taking action with other federal agencies to try to reduce temperatures in the Columbia River system. Regional spokesman Tom Conning cited their work cooling fish ladder water temperatures and releasing cold water from Dworshak Dam in Idaho between July and August.
“It’s helpful to remember that historical water temperatures in the Columbia and Snake rivers, before major development of dams, frequently exceeded modern state and federal temperature standards,” he added.
But the hot water’s impacts extend far beyond just hurting salmon. Clark County Public Health officials issued a warning that algae growth in the Columbia killed two dogs last year.
Over the past five years, the Washington State Department of Ecology has given nearly $1 million in grant money to municipalities to battle blooms in lakes around the state.
The warmer conditions also favor fish species such as northern pikeminnow, which harm the river’s ecology and cost the government millions of dollars in creative population-management schemes like fish bounty programs.
Over the course of the 20th century, the federal government built the hydropower system. It transformed the river from a natural system revolving around massive, ice-cold spring runoff into a finely tuned series of controlled reservoirs enabling billions of dollars in power to be generated and goods to be moved each year.
The 2023 study found those dams were a key cause of the Columbia’s 4-degree warming, and broader government research has found that’s true for most dams.
Other drivers of that warming include dwindling snowpacks and hotter air temperatures — both caused by climate change. Human-made causes, such as water withdrawals for farm irrigation and spawning habitat destruction, also compounded the problem, the study said.
The warmer temperatures extend throughout the basin — a problem that both Hatch and Bogaard said complicated the challenge salmon face.
The most recent Hot Water Report shows water in all four of the lower Columbia reservoirs has already crossed 68 degrees this year. And half of the four Snake River dams crossed that same threshold, with the other two not far behind.
Last year, the reports show, temperatures routinely crossed 70 degrees and often surpassed 72 degrees behind most of the eight dams that salmon must cross before accessing the hundreds of miles of pristine spawning grounds on the Snake River.
The hot temperatures on the lower Columbia slow down fish, draining their reserves even before they face four more dams on the lower Snake.
Columbia Basin salmon and steelhead returns were between 10 million and 18 million fish before the hydropower system. Recently, they’ve numbered about 2.3 million.
Wild fish, in particular, have suffered. Most wild Columbia Basin salmon and steelhead runs are less than 5 percent of their pre-1850s levels, a 2022 National Oceanic and Atmospheric Administration report found.
Currently, 13 Columbia Basin runs are under Endangered Species Act protections.
For Bogaard, the purpose of the Hot Water Report is explaining the extent of the crisis salmon face and highlighting solutions that government research has found will increase their survival, like removing the Lower Snake River dams.
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“Humans in recent decades have pushed them beyond their limits of resilience,” he said about the fish. “They’re able to endure spikes and short-term episodes of warm water, hot water. But they need to get relief, and they need to have refuges in this river system that allow them to recover.”
But that seems unlikely, at least in the near future, with the Trump administration gutting salmon recovery programs across the basin and ending the most viable path to an unobstructed Lower Snake River last month.
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