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SOS Blog

Save Our Wild Salmon

Hot Water Report 1


Welcome to Save Our wild Salmon’s Hot Water Report 2021. During the summer, this weekly report is providing updates on real-time water temperatures in the lower Snake and Columbia river reservoirs via graphs and analyses, reports on the highest weekly water temperature at the forebay/reservoir of each dam, and the status of adult returns for different salmon and steelhead populations as they make their way back to their natal spawning grounds. We’ll share information from scientists, fishers, guides, advocates, and other experts about the challenges facing the Columbia and Snake rivers - and opportunities we have to restore healthy rivers and to recover abundant fish populations and the many benefits they deliver to the Northwest’s culture, economy, and ecology.

The once-abundant anadromous native fish populations that call the Columbia-Snake River Basin home are struggling to survive primarily due to multiple harmful effects caused by the system of federal dams and their reservoirs. The federal hydro-system creates conditions that harm and kill both juvenile and adult fish, including by elevating water temperatures in large, stagnant reservoirs, especially in the summer months. As cold water species, salmon and steelhead begin to suffer harmful effects when water temperatures exceed 68° Fahrenheit. The longer and higher temperatures rise above 68°F, the greater the harm, including disruption in their migration, increased metabolism, increased susceptibility to disease, reduced fecundity or reproductive potential (by reducing egg viability), suffocation, and in the worst case - death.

These harmful hot water episodes above 68 degrees in the Columbia and Snake rivers are increasing in duration, frequency, and intensity. Our changing climate is making an already bad situation for the Northwest’s emblematic fish worse. Our region and nation must take urgent action to cool these waters or we will lose these species forever. Restoring a freely flowing lower Snake River by removing its four federal dams is our best and very likely only option for lowering water temperatures in this 140-mile stretch of river in southeast Washington State. Restoring the Snake River is one essential part of what must be a larger regional strategy to protect and rebuild healthy, abundant salmon and steelhead populations in order to benefit other fish and wildlife populations, including critically endangered Southern Resident orcas, to honor tribal rights, and to ensure prosperous communities across the Northwest.

Will you be on the river this summer? Do you have a story or photo you would like to share? Please send them to Martha Campos

The Hot Water Report is a joint project of the Save Our wild Salmon Coalition, Washington Sierra Club, Columbia Riverkeeper, Idaho Rivers United, National Wildlife Federation, Snake River Waterkeeper, Northwest Steelheaders, Defenders of Wildlife, and Endangered Species Coalition.

II. READING THE DATA - Lower Snake and Columbia River Temperatures


The daily mean temperature at the four reservoir forebays (immediately upstream from the dam) in the lower Snake River (above) and the lower Columbia River (below) for 2021 is represented with solid lines and their 10-year average (2011-2021) temperatures with dashed lines of the same color. The dotted horizontal line across the graph represents the 68°F “harm threshold” for adult and juvenile fish. Salmon and steelhead begin to suffer harmful effects when water temperatures exceed 68° Fahrenheit. The longer temperatures remain above 68°F and the higher the temperatures rise above 68°F, the more severe the effects.

Water temperatures remain high - and harmful - to salmon and steelhead in the lower Snake and lower Columbia River reservoirs: On the lower Snake River, the Ice Harbor, Little Goose and Lower Monumental reservoirs remain well above the threshold (68 degrees) this week. The Ice Harbor Dam reservoir has consistently maintained mean temperatures above 71°F, and with a high mean temperature of 71.96°F on July 22 and July 23. The Lower Monumental Dam had high mean temperatures of 70.52°F on July 22 and July 23.

On the lower Columbia River reservoirs, current temperatures remain above the 10-year averages for this time of the year, and all reservoirs register temperatures above 69°F. On July 25, 2021, The Dalles Dam reservoir had the highest mean temperature of 71.96°F. This week, the John Day Dam reservoir had the second highest mean temperature of 71.42°F.

A note on the lower Snake River Water Temperature Graph: The mean water temperature data from these reports comes from the USGS Current Conditions for Washington State and the 10-year average water temperature data comes from the Fish Passage Center. USGS began recording water temperatures at Ice Harbor and Lower Monumental on June 16, 2021, Little Goose on June 19, 2021, and Lower Granite on June 18, 2021. Although we are not able to compare spring water temperatures to summer water temperatures, we can see June temperatures rising above the 10-year average and all water temperatures in the lower Snake River are above 60°F.


On the lower Snake River this week, the reservoir behind Ice Harbor Dam registered the highest temperature at 72.50°F - significantly warmer than what coldwater fish require. Lower Monumental Dam reservoir had the second highest temperature at 71.24°F.

On the lower Columbia River, all reservoirs registered high temperatures above 70°F for multiple days. The Dalles Dam had the highest temperature this week at 72.32°F, followed closely by the Bonneville Dam with a high temperature of 72.14°F.

Temperature data included in these reports come from the USGS Current Conditions for Washington State and the Fish Passage Center. Graphs and tables were assembled by SOS Staff.


two sockeye lesions SMALLHeat-stressed sockeye salmon returning to the Columbia and Snake rivers are dying this summer. Columbia Riverkeeper released heartbreaking video footage and images that show sockeye with large, open lesions and fungus. Sockeye are especially sensitive to water temperatures above 68 degrees; hot waters make them highly susceptible to fungus growth on their skin and to open wounds.1

Columbia Riverkeeper captured this video on July 16 in the Little White Salmon River - a tributary to the lower Columbia River. Waters in the lower Columbia River currently exceed 71 degrees Fahrenheit - hotter than the legal (and biological) limit of 68°F, which scientists have identified as critical for protecting salmon.

You can listen to Umatilla Tribal member Don Sampson talk about what this means for salmon in this video.

Sockeye salmon spawn in mountain lakes above the Snake and upper Columbia rivers.2 However, due to the current high water temperatures, sockeye are taking refuge in small, cooler tributaries like the Little White Salmon, delaying their natural upstream migration.3 The Little White Salmon River does not support sockeye spawning, and scientists believe it is highly likely that they will die from disease and heat stress before they are able to reproduce.2

Columbia Basin fish are increasingly in crisis today - thirteen distinct populations are at risk of extinction today. Snake River sockeye are on the federal Endangered Species list and among the most imperiled.
The elevated water temperatures caused by the federal reservoirs and made worse by a changing climate must be addressed, or we will lose these fish.

The four lower Snake River dams kill significant numbers of juvenile (smolts) and adult fish, as the dam’s reservoirs create large, stagnant pools that absorb heat from the sun, reaching lethal temperatures for salmon. These bodies of water inundate and destroy diverse micro-habitats that healthy rivers support, including cold-water refuges that salmon and steelhead rely upon during their migration in the summer months. When available, pockets of cold water can enable adult (moving upstream) and juvenile fish (moving downstream) to rest and recover before continuing their migration. Unfortunately, rising temperatures and reductions in snowpack in recent decades due to climate change are contributing to lower survival and reproductive success for already endangered salmon and steelhead.

The lower Snake and Columbia River dams have disrupted the salmon’s life cycle in various ways, including driving water temperatures past 68°F in the summer for weeks at a time. Hot water temperature affects salmon behavior, reproduction, and survival (adult salmon have difficulty migrating upstream when water temperatures exceed 68°F).4 Migration stops altogether when water temperatures reach 72 to 73°F.4 Salmon that have stopped or slowed their migration, and languish for days or weeks in warm water, often die from the associated stress and disease (see Issue 1 for more information). On the lower Snake River last week, the reservoir behind Ice Harbor Dam registered the highest temperature at 73.22°F. This week, the Ice Harbor Dam is still well above 68 degrees - with a high temperature of 72.50°F. Similarly, on the lower Columbia River, the Dalles Dam had a high temperature last week and this week at 72.32°F. Salmon are a keystone species, and their loss sends a ripple effect to other species and the ecosystem as a whole. Restoring the lower Snake River is our nation’s very best salmon and river restoration opportunity, and it is our only feasible option for addressing dangerously high water temperatures. River restoration will also help address other problems created for fish by the dams. It will, for example, significantly reduce predator populations and, by increasing current velocity, significantly decrease juvenile salmon migration times to the estuary. All things considered, bypassing the lower Snake River dams is an essential ingredient to protect salmon and steelhead from extinction and to rebuild their populations and the many benefits they provide for the people and ecosystems of the Pacific Northwest and nationwide.

1. The Guardian: Salmon nearly roasted alive in Pacific noth-west heatwave captured on video (July 27, 2021)
2. Columbia Riverkeeper: Salmon Dying from Hot Water in Columbia River (July 27, 2021)
3. NOAA Fisheries: 2015 Adult Sockeye Salmon Passage Report, p. 25 (2016)
4. Columbia Riverkeeper: Hot Water: Dammed rivers and climate change create lethal conditions for key species (July 27, 2021)


Why are the fish dying at the mouth of the Little White Salmon River?
These fish are adult sockeye salmon that just returned from the ocean. Right now, they should be migrating much further up the Columbia River to spawn in mountain lakes in the Okanogan, Yakima, and Snake river systems. Snake River sockeye are on the federal Endangered Species list and dangerously close to extinction.

Map of the Columbia River Basin. Purple oval shows the mouth of the Little White Salmon River. Red stars show major sockeye spawning areas. Black dashes show large hydroelectric dams. >>

Why are sockeye there? Is it natural?
Because the Columbia River is too hot, these sockeye are taking refuge in small, cold tributaries like the Little White Salmon River instead of completing their natural upstream migration.1 The Little White Salmon River does not support sockeye spawning, and sockeye are only seen here when Columbia gets too hot.

Why is the Columbia River too hot?
Dams on the Columbia and Lower Snake Rivers create large, stagnant reservoirs that soak up the sun’s energy, making the water too hot for salmon.2 Climate change is making this bad situation even worse.3

Will these sockeye eventually go upstream to spawn?
No. They will very likely die in the Little White Salmon River of disease and heat stress, without spawning.4

Is this a one-time, freak occurrence?
No. In 2015, when roughly 250,000 sockeye died in the Columbia and Snake rivers because of hot water, sockeye also sought refuge and died in the Little White Salmon River and nearby tributaries.5 Scientists predict that fish kills like this will become more common as dams and climate change continue to warm the rivers and likely cause the extinction of Snake River sockeye6—unless we address how the dams warm the Columbia and Snake rivers.

Why do these fish look like they have mold on them?
The fuzzy-looking white patches on these sockeye are likely a fungal infection that attacks salmon stressed by hot water.7

How many sockeye will die of warm water this year?
It’s too soon to tell. Here’s what we know: Right now, tens of thousands of sockeye remain in the dangerously warm Columbia and Lower Snake rivers. As the rivers get even hotter in August and September, many of these fish may perish.

FAQ References:
1. See NOAA Fisheries, 2015 Adult Sockeye Salmon Passage Report, p. 25 (2016).
2. U.S. EPA, Temperature Total Maximum Daily Load for the Columbia and Lower Snake Rivers, pp. 47–50 (May 18, 2020) (Columns E and F in Tables 6-6 through 6-9 show the heat pollution caused by dams individually and cumulatively during the summer and fall.).
3. Id. at 70 (explaining that climate change has already caused water temperature increases of 1 to 2 °C in the Columbia and Snake rivers).
4. See U.S. EPA, Columbia River Cold Water Refuges Plan, p. 34 (2021) (explaining that sockeye do not successfully use cold water refuges).
5. See Note 1, supra.
6. Crozier et al., Snake River sockeye and Chinook salmon in a changing climate: Implications for upstream migration survival during recent extreme and future climates, 15 PLoS ONE 9, p.2 (2020) (modeling survival probability of Snake River sockeye assuming water temperatures resulting from dams and future climate conditions).
7. See Note 1, supra.


 Martha Bio picMartha Campos is the Hot Water Report Coordinator with Save Our wild Salmon this summer while she resides on Kizh/Tongva ancestral lands in California. Martha holds a BA from the University of California, Davis in Native American Studies (and two minors: Environmental Policy, Analysis, and Planning and Climate Science and Policy) and is a queer, non-binary person of color with ancestral roots in Mexico.

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