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SOS Blog

Save Our Wild Salmon

HWR Banner sockeye salmon with lesions image by Conrad GowellSockeye salmon with lesions dying from hot water in the Columbia-Snake River Basin ©Conrad Gowell


Welcome to the 2023 Hot Water Report: Warming Waters in the lower Snake and Columbia rivers.

During the summer, this weekly report provides an update on real-time water temperatures in the lower Snake and Columbia river reservoirs via graphs and analyses, a summary of the highest weekly water temperatures at the forebay/reservoir of each dam, and a monthly status of adult returns for different salmon and steelhead populations as they make their way back to their natal spawning grounds. We’ll report first-hand from scientists, Tribal members, fishing guides, advocates, and other experts about the challenges facing these rivers - and our opportunities to improve and restore them - in order to recover healthy, resilient fish populations and the benefits they deliver to Northwest communities, other fish and wildlife populations (including the critically endangered Southern Resident orca), and ecosystems.

The once-abundant anadromous fish populations of the Columbia-Snake River Basin are on the brink of extinction today due primarily to harms caused by federal dams and their warming reservoirs. The Columbia-Snake federal hydro-system harms and kills both juvenile and adult fish in multiple ways, including by elevating water temperatures in the summer months in their large, stagnant reservoirs. These cold-water fish begin to suffer harmful effects when water temperatures exceed 68° Fahrenheit.

Today, harmful hot water episodes above 68°F in the lower Snake and Columbia rivers are increasing in duration, frequency, and intensity. Our anthropogenically changing climate is worsening these harmful impacts on salmon survival and increasing the urgency to take action to maintain cool water temperatures - or we will lose these species forever. Recovering abundant salmon populations by restoring a free-flowing lower Snake River through dam removal is a once-in-a-lifetime opportunity for the Northwest and nation; and our only feasible option to address hot water temperatures created by the four lower Snake River dams.

A restored, healthy, and resilient lower Snake River is necessary to uphold our nation's promises to Tribes and sustain salmon populations in perpetuity. Dam removal will reconnect the Northwest’s most emblematic fish to over 5,500 miles of pristine, cold-water river and streams in Idaho, Oregon, and Washington.

The Hot Water Report is a joint project of the Save Our wild Salmon Coalition, Association of Northwest SteelheadersColumbia RiverkeeperEarthjusticeEndangered Species CoalitionEnvironment OregonIdaho Conservation League, Idaho Rivers United, Natural Resources Defense Council, National Wildlife FederationNorthwest Sportfishing Industry AssociationOrca NetworkSierra Club, Snake River Waterkeeper, Wild Orca and Wild Steelhead Coalition.

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

Click on the image to view the graph. 

Introduction: The daily average temperature at the four reservoir forebays (immediately upstream from the dam) in the lower Snake River (above) and the lower Columbia River (below) for 2023 is represented with solid lines and the 10-year average (2013 - 2023) temperatures with dashed lines of the same color. The dotted line across the graph represents the 68°F “harm threshold” for adult and juvenile fish.

The longer and the higher these temperatures rise above 68°F, the greater the harm, including: migration disruption, increased metabolism, increased susceptibility to disease, reduced reproductive potential (by reducing egg viability), suffocation (warm water carries less oxygen), and in worst case - death.

Reservoirs are large, slow-moving pools which absorb enormous amounts of solar radiation, causing warm waters. These waters inundate and destroy diverse micro-habitats that healthy rivers support, including cold-water refuges that salmon and steelhead rely upon during summer migrations. Without these vital pockets of cold water, salmonids cannot rest and recover on their journeys – adults moving upstream to spawn and juveniles moving downstream to the ocean. Rising temperatures and reductions in snowpack in recent decades due to climate change have resulted in warmer waters, which results in lower survival and reduced reproductive success for salmon and steelhead. The lower Snake River dams exacerbate these already warmed waters, creating conditions that harm these fish.

Click on the image to view the graph. 

Discussion of data: Since April, temperatures in the lower Snake River and the lower Columbia River reservoirs have steadily increased. Water temperatures in June this year are considerably higher than 10-year average. This week, the reservoir behind the Lower Granite Dam had the highest recorded average temperature of 68.63°F on July 5. Similarly, Little Goose reservoir had the second highest recorded average temperature of 68.49°F on July 5. 

On the lower Columbia River, the reservoir behind the John Day dam had the highest recorded average temperature of 69.98°F on July 5. Both juvenile and adult salmon are now experiencing water temperatures above the 68°F in several of the stagnant reservoirs they migrate through. 

Below, we present the highest temperatures for each reservoir on the lower Snake and Columbia rivers for June 28 - July 5.


On the lower Snake River, the reservoir behind the Lower Granite Dam registered the highest water temperature at 68.67°F on July 4, and the Little Goose reservoir had the second highest temperature at 68.49°F on July 5. On the lower Columbia River, the John Day reservoir registered the highest water temperature at 70.88°F on July 5.

A note on the data: The 2023 lower Snake River and lower Columbia River water temperature data presented in the Hot Water Report are collected from the Columbia River DART program by Columbia Basin Research, University of Washington, using data courtesy of the U.S. Army Corps of Engineers (USACE). The 10-year average water temperature data is courtesy of the Fish Passage Center. There is no data available for the Lower Monumental 10-year average water temperature, and McNary reservoir water temperature data is collected from USACE with current available data. Graphs and tables were assembled by SOS Staff.

IV. Salmon and Steelhead’s Role in NW Biodiversity

For millennia, wild Snake and Columbia River salmon and steelhead have delivered vast cultural, economic, nutritional, and ecological benefits to the people, fish, and wildlife of the Northwest. Prior to the dam construction, the pristine, clear, cold waters of the Snake River Basin were home to millions of adult salmon and steelhead.1 Each year, they would return from the Pacific Ocean, swimming against the current in search of their natal spawning gravels, and deliver many millions of pounds of high-quality marine-derived nutrients to the landscape and wildlife of the Northwest.

Before the dams - when these rivers flowed freely - juvenile salmon and steelhead took as few as five days to complete their migration to the ocean. Today, however, the dams and reservoirs have stilled the current, and salmon now require a month or more to reach the ocean.2 Wild fish return as adults at just 1-3 percent of historic levels. Many of the Columbia-Snake River Basin salmon runs have been locally extirpated. Thirteen populations, including all four Snake River populations, are listed as threatened or endangered under the Endangered Species Act and remain at risk for extinction.

Salmon Ecology

Art Imitates Life ©Amy Gulick/

The ecological significance of salmon is magnificently multifaceted. Salmon and steelhead are a critical nutrient link between oceans, rivers, streams, forests, and wildlife. Salmon runs function as enormous pumps that provide vast amounts of marine nutrients from the ocean to river systems.3 Over 137 species benefit from and utilize the ocean-origin nutrients that salmon and steelhead deliver.4 Because of their vast ecological impact, salmon are considered a keystone, connector, and indicator species. In other words, salmon have unique and substantial effects on their own and neighboring environments such that no other species can replace its particular ecological role. When keystone species are removed, the entire ecosystem typically collapses.

The state of salmon populations reflect the overall health of the ecosystem as a whole. When salmon populations are in peril, it indicates that the entire ecosystem is unhealthy and/or under stress.

Due to the elevated water temperatures in the stagnant reservoirs and other harms caused by the lower Snake River dams, salmon runs have been in steep decline for several decades. These population declines have dramatically reduced the amount of vital nutrients transferred annually from the ocean to freshwater ecosystems, and surrounding riparian habitat. Restoring wild salmon and steelhead will strengthen this ancient connection between saltwater, freshwater, and watersheds and help to restore former productivity, and increase the overall biodiversity ecosystem across the basin and in Northwest coastal waters.

Interdependence between people, rivers, and salmon

Scaffold fishing at Celilo Joe Palmer fishing from a hanging scaffold on Standing Island. Aug 1952. ©Columbia River Inter-Tribal Fish Commission/Raymond Mathen

Salmon are not only ecologically significant – they are also profoundly fundamental to Northwest Tribes’ spiritual and cultural identity, economic prosperity, and food system sovereignty since time immemorial.5

“The importance of the first salmon ceremony has to do with the celebration of life, of the salmon as subsistence, meaning that the Indians depend upon the salmon for their living. And the annual celebration is just that – it’s an appreciation that the salmon are coming back. It is again the natural law; the cycle of life. It’s the way things are and if there was no water, there would be no salmon, there would be no cycle, no food. And the Indian people respect it accordingly.” —Antone Minthorn, Umatilla6

Since time immemorial, Northwest Tribes have stewarded and harvested salmon in the Snake River Basin. Recently, the Affiliated Tribes of Northwest Indians and the National Congress of American Indians passed resolutions calling for the removal of the lower Snake River dams and “actions that will be needed for salmon and river restoration in the Columbia Basin: to support salmon, steelhead, lamprey, and native fish, within their complete ecosystems – from the orca in the ocean and Puget Sound to the nutrients salmon supply to the furthest inland streams – and to support the Northwest [Tribal] people who have lived with these species in mutual dependence since time immemorial.”7

Salmon and steelhead migration tells the tale of an exceptional species, yet their significance is not merely a story of ecological awe. These fish also exemplify the reciprocal relationships between people and planet. At this moment, we have an urgent opportunity to restore ecosystem health across the basin and recover salmon and steelhead to abundance by removing the four lower Snake River dams and replacing the dams’ services. For additional information, please visit

1. Columbia River Inter-Tribal Fish Commission: Columbia River Fish Species. 
2. Spokesman-Review: Environmentalists, politicians clash over...hearing to defend Snake River dams (June 28, 2023)
3. Wild Salmon Center: Why protect Salmon
4. The National Wildlife Federation: Chinook Salmon.
5,6. Columbia River Inter-Tribal Fish Commission: Tribal Salmon Culture. 
7. Affiliated Tribes of Northwest Indians (ATNI): Resolutions # 2022 - 23 Supporting and thanking all the Leaders who have Heard the ATNI Tribes’ Voices, and Especially the Biden-Harris Administration, and Senator Murray and Governor Inslee, for Steps they are taking toward Salmon and River Restoration in the Pacific Northwest, and toward Long-Ignored Tribal Justice for our Peoples and Homelands 


1. The Seattle Times: As the West’s dam removal movement presses on, could the Lower Snake be next? (June 14, 2023)

2. Seattle Times Opinion: Salmon restoration is a matter of ecological, cultural survival by Sen. Claudia Kauffman D-Kent (June 14, 2023)

3. Spokesman-Review Guest Opinion: Four Tribal chairs: We need a Columbia Basin Initiative for salmon, tribes and energy by Gerald Lewis, Kat Brigham, Jonathan W. Smith, Sr. and Shannon F. Wheeler (June 4, 2023)

4. Everett Herald Opinion: Sen. Cantwell should join effort to retire Snake dams (May 26, 2023)

5. Public News Service: Historic Step Forward for Snake River Dam Replacement in WA Budget (May 18, 2023)

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