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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 federal 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.

Many once-abundant anadromous fish populations - fish that hatch in freshwater, go to sea, and return to freshwater to spawn - in 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.

This week, on the lower Snake River, the reservoir behind the Ice Harbor Dam registered the highest water temperature at 72.36°F on August 5. Both juvenile and adult salmon have experienced water temperatures above the 68°F “harm” threshold for over a month this summer. In Issue 6, Miles Johnson, Legal Director for Columbia Riverkeeper, uncovers the critical role of the Clean Water Act in addressing dams’ hot water pollution, also known as heat pollution, to protect endangered salmon and steelhead from extinction. This issue provides an in-depth review of how federal agencies such as the U. S. Army Corps of Engineers and the Bonneville Power Administration have purposely delayed the implementation of the Clean Water Act’s requirements to address heat pollution for over two decades.

The four federal dams and their hot water reservoirs on the lower Snake River continue to be main obstacle to salmon and steelhead recovery. We urgently need federal agencies—especially the Army Corps of Engineers and Bonneville Power Administration—to actively support comprehensive regional solutions that include the removal of the lower Snake River dams and replacement of their services in order to restore a healthier, cooler and resilient lower Snake River, uphold our nation's promises to Tribes and sustain salmon populations in perpetuity.

The Hot Water Report is a joint project of the Save Our wild Salmon Coalition, American RiversAssociation 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 - Water Temperatures in the Lower Snake and Columbia Rivers

Figure 1. Lower Snake River Water Temperatures - 2023 Daily Average and 10-year Average. Click on the image to view the graph.

Introduction to the data:
The daily average temperature at the four reservoir forebays (measured with sensors stationed at various depths below the reservoir surface, immediately upstream from the dam) in the lower Snake River (shown above) and the lower Columbia River (shown 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 dissolved oxygen), and in the worst case - death.

Reservoirs are large, stagnant pools that absorb enormous amounts of solar radiation, and cause the water to warm. These waters inundate and destroy diverse micro-habitats that healthy rivers support, including cold-water refuges that salmon and steelhead rely upon during their migration. 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 create warmer waters, which results in lower survival and reduced reproductive success for salmon and steelhead.

LCR daily avg. temps 88Figure 2. Lower Columbia River Water Temperatures - 2023 Daily Average and 10-year Average. 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. As Figure 1 shows, this week, the reservoir behind the Ice Harbor Dam had the highest average temperature of 71.97°F from August 6. Lower Monumental Dam's reservoir had the second highest average temperature of 71.09°F on August 6.

As Figure 2 shows, this week the reservoirs behind The Dalles and John Day dams registered the highest average temperature of 71.60°F.

Both juvenile and adult salmon have now experienced water temperatures consistently above the 68°F “harm” threshold for more than a month.

Below, we present the weekly high water temperatures for each reservoir on the lower Snake and Columbia rivers for August 3 - August 8.

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.


This week, on the lower Snake River, the reservoir behind the Ice Harbor Dam registered the highest water temperature at 72.36°F on August 5, and the Lower Monumental Dam registered the second highest temperature at 71.20°F on August 6.

LCR high temps 88This week, on the lower Columbia River, The Dalles Dam reservoir registered the highest water temperature at 72.32°F on August 8.

IV. Hot water vs. the Clean Water Act
by Miles Johnson, Columbia Riverkeeper, Legal Director

The Clean Water Act is our nation's flagship law for protecting healthy streams, rivers, and lakes. Enacted when some of our nation’s waterways were so contaminated that they actually caught fire, the Clean Water Act’s common-sense goal is to ensure that rivers and lakes remain clean enough to support fishing, swimming, and (after appropriate treatment) drinking. Although significant threats to water quality obviously remain, the Clean Water Act has proven to be one of our nation’s most effective—and most popular—environmental laws.

All of this prompts the question: Does the Clean Water Act contain the tools and authorities to address hot water pollution caused by dams on the Lower Snake and Columbia rivers? In theory, the answer is yes. Columbia Riverkeeper and others are working hard to translate that theory into action to protect endangered salmon and steelhead from the dams’ heat pollution.

Here is a quick tour of the legal landscape: The Clean Water Act defines heat as a pollutant. The states of Oregon and Washington long ago recognized that the Columbia and Lower Snake rivers have too much heat pollution to safely support salmon and steelhead. After litigation by Columbia Riverkeeper and others in 2021, the U.S. Environmental Protection Agency (EPA) issued a heat pollution budget (called a Total Maximum Daily Load analysis or TMDL) for these rivers. EPA’s heat pollution budget identified the dams as the largest sources of heat pollution and calculated each dam’s heat pollution limit.1 New Clean Water Act discharge permits for the dams (issued because of recent litigation by Columbia Riverkeeper) made EPA’s heat pollution limits enforceable and required the Army Corps to develop plans to reduce its dams’ heat pollution.

If the Clean Water Act applies to heat pollution, why are we just beginning to regulate heat pollution from these dams? Unfortunately, the federal agencies that operate the dams and sell the electricity have long sought to obscure, and avoid responsibility for, their dams’ heat pollution. Nearly twenty years ago, the Army Corps prevailed upon EPA to bury a draft of the heat pollution TMDL. When EPA took up the draft TMDL again several years later, the Army Corps asked EPA to pretend that the temperature impacts of the dams were part of the natural river system and beyond the reach of the Clean Water Act. Rebuffed, and concerned that EPA would issue a TMDL limiting heat pollution from the dams, the Army Corps pressured Oregon to eliminate salmon and steelhead as Clean Water Act-protected uses of the Columbia River2 (an invitation Former Oregon Governor Kulongoski pointedly refused). After EPA finally issued the heat pollution TMDL, the Army Corps unsuccessfully appealed a decision by the Washington Department of Ecology that made the TMDL’s heat pollution limits legally enforceable.3 In short, the Army Corps and other federal dam agencies like Bonneville Power Administration have purposely delayed the implementation of the Clean Water Act’s basic requirements for over two decades. Meanwhile, Snake River salmon and steelhead moved steadily towards extinction.

Sockeye salmon with lesions dying Conrad GowellSockeye salmon with lesions dying from hot water in the Columbia-Snake River Basin ©Conrad Gowell

What will happen next? Despite the Army Corps’ prolonged resistance, new Clean Water Act discharge permits require the Army Corps to create and implement plans to meet the TMDL’s heat pollution reduction targets for each dam. The plans must evaluate actions such as drawing down (lowering the level of) reservoirs during hot months to reduce heat pollution. Indeed, the Army Corps has submitted the outline of its plans for the lower Snake River dams; they identify operating the reservoirs below the Minimum Operating Pool level as one of the Army Corps’ “Future Measures/Strategies” to address the dams’ heat pollution. (Note: The Minimum Operating Pool (MOP) is the reservoir level where barges can use the river. Operating below MOP would also significantly decrease power generation.)  

Refining and implementing these studies will take several years. If the Army Corps’ past reluctance to comply with the Clean Water Act is any guide, Columbia Riverkeeper and others will need to remain engaged to ensure outcomes that actually benefit salmon and steelhead. However, if the Army Corps doesn’t make and implement water quality attainment plans and meet the TMDL’s heat pollution limits, the Army Corps will continue to be vulnerable to Clean Water Act enforcement lawsuits. The Washington Department of Ecology could also revoke the Army Corps’ Clean Water Act certifications, which would cast into doubt the Army Corps’ legal authority to continue operating the dams.


The bottom line remains: Wild salmon and steelhead who return to the Snake River Basin are struggling for survival. Hot water continues to be a major driver of fish mortality. The federal agencies—especially the Army Corps of Engineers and Bonneville Power Administration—persistently seek to mislead, obfuscate, delay, and deny. Today, they are part of the problem when we need them to be part of the solution. Their bad behavior is driving up salmon recovery costs and underscores the urgent need for the Biden Administration to deliver a comprehensive regional solution that includes the removal of the lower Snake River dams and replacement of their services—as quickly as humanly possible!

View the past Hot Water Report issues here: Hot Water Reports - Compiled

1. U.S. EPA, Columbia and Lower Snake River Temperature TMDL, pp. 55–59 (Aug. 13, 2021) (Columns E and F in Tables 6-6 through 6-10 show the heat pollution caused by the four Lower Snake River dams individually and cumulatively during the summer and fall.).
2. See, e.g., Letter from Army Corps, Bureau of Reclamation, and EPA to Oregon Department of Environmental Quality encouraging Use Attainability Analyses for the Columbia and Snake Rivers (May 9, 2005).
3. See, e.g., Army Corps, Notice of Appeal to the Washington Pollution Control Hearings Board re Ecology Order No. 18146 Granting Water Quality Certification for the Bonneville Project (June 8, 2020).

 V. Snake River sockeye run sputters - an article by Eric Barker, Lewiston Tribune

“Strong early numbers at Bonneville Dam haven’t led to a lot of fish making it to Lower Granite Dam. The promising start to the Snake River sockeye run appears to have melted away as the adult fish progressed upstream.

Sockeye that return to Redfish, Pettit and Alturas lakes in the shadow of Idaho’s Sawtooth Mountains are the most imperiled salmon run in the Columbia River basin and listed as endangered by the federal government. But in mid-July, fisheries managers at the Idaho Department of Fish and Game were hopeful at the number of Idaho-bound sockeye detected at Bonneville Dam, the first in a series of dams salmon and steelhead from the Columbia and Snake rivers must pass on their way home. They estimated 4,351 had navigated past the dam, a number that would be the most since 2012.

Even so, there already were signs that those fish faced tough conditions. Flows in the Columbia and Snake were dropping and water temperatures were already above seasonal norms at federal dams on the two rivers.

On average, 40% to 70% of adult Snake River sockeye counted at Bonneville Dam make it to Lower Granite Dam on the Snake River. Known as conversion, the rate varies based on river conditions.

In mid-July, Eric Johnson, a sockeye specialist with the Idaho Department of Fish and Game, predicted survival would be in the 40% range this year. Fast forward two weeks and the Bonneville-to-Granite conversion rate is only at 20%. That compares to a conversion rate of 66% in 2022.

'It’s definitely lower than average and lower than we would have hoped for,' Johnson said. 'We are not completely through the run. I expect that it will probably improve a little bit but I’m not expecting it’s going to improve too much.'”

Read the full article here.

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