Dams = Hot Water Crisis on the Columbia

Catastrophic. Devastating. These are just some of the words scientists are using to describe the crisis unfolding on the Columbia. Dams are the main culprit causing the salmon crisis. Salmon need cool water to survive. Dams heat up the river by decreasing river flow and creating huge, stagnant reservoirs that soak up the sun. Compounding the dam problem, this year’s low snowpack coupled with hot water temperatures are straining already imperiled salmon runs. News reports from across the region paint a sobering picture: salmon runs struggle to cope with the harsh realities of dams, poor water management, and climate change.

Dead sockeye salmon, White Salmon River on July 28, 2015.

Highlights of recent news reports include:

  • Scientists estimate that more than 277,000 sockeye, about 55 percent of the total run, returning from the ocean to spawn died in the Columbia and Snake rivers due to warm water temperatures in 2015.  For the Endangered Snake River run of sockeye salmon, the toll was much worse: 99% of these fish died between Bonneville Dam and their spawning grounds in central Idaho.
  • River temperatures across the Northwest are entering—and in some rivers have already reached—lethal territory for salmon. Fish become stressed once river temperatures reach the 60s. Lethal effects set in once temperatures exceed the low 70s.
  • Last summer, the Columbia’s temperature at Bonneville Dam exceeded 72 degrees. That marks the hottest temperature since at least 1950. According to the U.S. Fish and Wildlife Service, this is the third summer in a row where water temperatures are higher than ever.
  • In July alone, more than 100 Chinook salmon died in the Middle Fork John Day River when temperatures there exceeded 70 degrees. Biologists also report dead fish in Oregon’s Willamette and Deschutes rivers.

Study Suggests Solutions to the Hot Water Crisis
This summer’s crisis begs the question: Has anybody studied why the Columbia is too warm and what we can do? Turns out, the U.S. Environmental Protection Agency (EPA) launched a major project to tackle hot water in the Columbia in the late 1990s and early 2000s. But the effort broke down. Stakeholders, including the federal agencies that operate dams and regulate water diversions, balked at the harsh realities of changing the status quo to protect cold water for salmon.

While EPA’s work did not prompt any actions to reduce water temperatures, the effort did culminate in a significant study, released in 2003, examining the root causes of elevated water temperatures in the Columbia and Snake rivers. The agency came to three core conclusions:

  • During the summer and early fall, the Columbia and Snake rivers are often too warm for healthy migrating salmon.
  • The rivers historically got too warm for healthy migrating salmon at certain times, but humans have significantly increased the intensity and duration of temperature problems.
  • Dams significantly impact temperature in the rivers; tributaries have a minor impact; point sources (i.e., factories, sanitary treatment plants) have only localized impacts.

EPA’s modeling suggests that the Columbia and Snake rivers warm up at approximately the same rate in the spring as they would without dams. But here’s the catch: the dams cause the rivers to remain warmer than natural during the late summer and fall, thereby increasing the number of days each year that the rivers are too warm for healthy salmon migration.

Dams are not created equal when it comes to temperature impacts. According to EPA’s study, the lower four Snake River dams—Lower Granite, Ice Harbor, Little Goose, and Lower Monumental—have a major impact on temperature. Together, these four dams can raise the Snake River’s temperature by two to four degrees Fahrenheit. That’s a stunning impact on water temperature.

On the mainstem Columbia, Grand Coulee Dam is by far the biggest temperature driver, capable of raising the water temperature by more than 11 degrees Fahrenheit.

Bottomline: EPA’s study suggests the need for major changes to the Columbia Basin hydroelectric system to protect endangered salmon runs.

Learn More
Columbia Riverkeeper is working with partners across the region to restore strong salmon runs on the Columbia. From working with river communities to protect the Columbia from dirty fossil fuel projects to suing the federal government to change dam operations that kill endangered salmon, we are working on multiple fronts to tackle the problem. When it comes to recovering the Columbia’s iconic salmon, defeat is not an option.

Are you seeing dead fish on the Columbia? If so, please email us photos noting location of fish to info(at)columbiariverkeeper.org. Please include your contact information in case we have questions.


AP, Half of Columbia River sockeye salmon dying due to hot water, July 27, 2015
Seattle Times, Snowpack drought has salmon dying in overheated waters, July 25, 2015
OPB, NW fish survival tested by warm waters and low stream flows, July 22, 2015

Columbia/Snake Rivers Preliminary Draft Temperature TMDL at 30 (July 2003) (stating that the maximum impact of Lower Granite, Little Goose, Lower Monumental, and Ice Harbor are 2.08° Celsius, 2.18°, 1.31°, and 1.20° Celsius, respectively).

Columbia/Snake Rivers Preliminary Draft Temperature TMDL at 30 (July 2003) (stating that Grand Coulee Dam’s maximum effect on temperature is 6.23° Celsius, which is equivalent to approximately 12° Celsius).