Sockeye 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 71.10°F on August 24. Both juvenile and adult salmon continue to experience water temperatures well above the 68°F 'harm threshold' for over 50 days. For Issue 9, we discuss this summer's adult returns for Snake River sockeye salmon. Unfortunately, hot water has prevented almost an entire generation of critically endangered Snake River sockeye from reaching their spawning grounds in Idaho. This year, just 24 natural-origin sockeye have been able to navigate through the lower Snake River dams and up to Idaho’s Stanley Basin to spawn. Sockeye salmon are nowhere near their recovery goals. Delisting from the Endangered Species Act requires an annual return of 2,500 natural-origin adult sockeye. For the Columbia Basin Partnership, 15,750 natural annual spawners are needed to meet the partnership's "medium" range abundance goals.
Restoring a free-flowing Snake River by removing its four dams (and replacing their services) is essential to provide cold, clean, healthy water for salmon and steelhead, to protect and recover these once-highly prolific fish from extinction, to uphold our nation's treaty commitments to Tribes, and to help feed critically endangered Southern Residents and other fish and wildlife species.
View the past Hot Water Report issues here: Hot Water Reports - Compiled
The Hot Water Report is a joint project of the Save Our wild Salmon Coalition, American Rivers, Association of Northwest Steelheaders, Columbia Riverkeeper, Earthjustice, Endangered Species Coalition, Environment Oregon, Idaho Conservation League, Idaho Rivers United, Natural Resources Defense Council, National Wildlife Federation, Northwest Sportfishing Industry Association, Orca Network, Sierra Club, Snake River Waterkeeper, Wild Orca and Wild Steelhead Coalition.
II. READING THE DATA - Water Temperatures in the Lower Snake and Columbia Rivers
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 (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 dissolved oxygen), and in the worst case - death.
The four reservoirs on the lower Snake River are large, stagnant pools that absorb enormous amounts of solar radiation that 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.
Discussion of data:
Since April, temperatures in the lower Snake River and the lower Columbia River reservoirs have steadily increased. As Figure 1 shows, the reservoir behind the Ice Harbor Dam had the highest daily average temperature of 70.77°F on August 30 and August 31. The Lower Monumental reservoir had the second highest daily average temperature of 70.53°F on August 25.
As Figure 2 shows, the reservoir behind the John Day Dam registered the highest average temperature of 72.32°F on August 25. Both juvenile and adult salmon continue to experience water temperatures well above the 68°F 'harm threshold' for over 50 days.
Below, we present the weekly high water temperatures for each reservoir on the lower Snake and Columbia rivers for August 24 - August 31.
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 hourly water temperature data is collected from USACE with current available data. Graphs and tables were assembled by SOS Staff.
III. WEEKLY HIGH WATER TEMPERATURES: August 24 - August 31
This week, on the lower Snake River, the reservoir behind the Ice Harbor Dam registered the highest water temperature at 71.10°F on August 24, and the Lower Monumental Dam registered the second highest temperature at 70.92°F on August 25.
This week, on the lower Columbia River, the John Day reservoir registered the highest water temperature at 73.04°F on August 27.
IV. Hot water kills most Snake River sockeye. Again.
By Miles Johnson, Legal Director for Columbia Riverkeeper.
What began as a promising run of endangered Snake River sockeye has ended in disaster. Again. This year, roughly 80% of the adult Snake River sockeye died prematurely in the reservoirs of the lower Columbia and lower Snake rivers. Hot water in these reservoirs prevented almost an entire generation of critically endangered fish from reaching their spawning gravels in Idaho—violating the Endangered Species Act and dealing another blow to the Shoshone-Bannock Tribes’ long-running effort to recover this unique and culturally important species.
Sadly, mass die-offs of endangered Snake River sockeye caused by hot water in the lower Columbia and Snake reservoirs are now common. In 2015, 96% of Snake River sockeye succumbed to hot water in the reservoirs. In 2021, 70% died when the rivers became too hot. Even in “good” years, hot water in the reservoirs kills a quarter of the breeding population of this endangered species.
Sockeye salmon with lesions dying from hot water in the Columbia-Snake River Basin ©Conrad Gowell
This dire situation underscores the need to improve the freshwater habitat that Columbia and Snake river salmon and steelhead depend on. Especially for Snake River fish that must pass eight dams and reservoirs to reach the ocean—and then those same eight dams and reservoirs to return to their natal streams to spawn—the federal hydro-system is the single largest source of mortality. Roughly half of all juvenile Snake River sockeye do not survive their downstream migration through the eight dams. Adult Snake River sockeye are often killed at similar or greater rates upon their return.
Sockeye salmon need cool water to survive, but they migrate upstream during the middle of the summer when reservoir temperatures begin to rise. As shown above and in previous Hot Water Reports, the Columbia and lower Snake reservoirs now routinely top 70°F for much of the summer. That’s a problem because adult salmon have difficulty migrating upstream when water temperatures approach 68°F. Migration stops altogether when water temperatures reach 72 to 73°F. Salmon that have stopped or slowed their migration, and languish for days or weeks in warm water, begin dying from stress and disease. Warm main-stem rivers that are dominated by reservoirs—like the Columbia and lower Snake—are especially dangerous to adult sockeye.
Given the risks from hot water, it’s no wonder that the National Marine Fisheries Service recently said that Snake River sockeye salmon are “at a high risk of extinction.” This year, just 24 wild sockeye were able to navigate through the lower Snake River dams and up to Idaho’s Stanley Basin to spawn. To get off the Endangered Species List, wild sockeye numbers would need to reach 2,500 wild adult fish. And the Columbia Basin Partnership has set a “medium” abundance goal of 15,750 wild spawners. Without big improvements in water quality, federal scientists predict that adult Snake River sockeye survival will further decline by 80% in coming years, likely resulting in extinction.
Un-damming the lower Snake River would not solve every water temperature problem in the Columbia River Basin. But un-damming the lower Snake would keep this 140-mile section of river cool enough for endangered sockeye, as well as reduce the cumulative stress that many sockeye succumb to upstream of the lower Snake.
V. 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
For our people to survive, we need salmon. Without salmon, there can be no Salmon People. We have a sacred relationship with – and obligation to – the salmon populations that call Nch’í Wána (Columbia River) home.
For nearly 100 years, Columbia and Snake River dams have been built and then operated – to this day and every day – on tribal homelands. The dams became a foundation of the modern Northwest economy. But that has come at an unjust price for Tribal Nations. Our peoples’ homes were flooded, our sacred sites destroyed, and the value of our lands and waters continues to be extracted in a manner that negatively impacts our natural resources. Salmon, our First Food, have been decimated.
Despite decades of dedicated restoration effort, salmon populations in the Columbia River Basin are on the brink of extinction.
This point of no return threatens salmon themselves, and our way of life. It violates the treaties our Nations hold with the United States.
This status quo is untenable. To avoid extinction, we must act now.
We urgently need a comprehensive Columbia Basin Restoration Initiative that restores salmon and other native fish populations to healthy and abundant levels; honors federal commitments to Tribal Nations; and delivers affordable, clean power.
Three key actions are necessary now to restore fish to healthy and harvestable levels for all.
First, fully fund habitat restoration work throughout the Columbia River Basin.
Second, replace the benefits of the four lower Snake River dams to enable breaching to restore the migration corridor to the best remaining salmon habitat in the lower United States.
Third, salmon must be returned to their native habitat in the upper Columbia River.
All three actions are “essential” to salmon recovery, as the National Oceanic and Atmospheric Administration has confirmed.
Gerald Lewis is Chairman of the Tribal Council of Yakama Nation.
Kat Brigham is Chair of the board of trustees of the Confederated Tribes of the Umatilla Indian Reservation.
Jonathan W. Smith, Sr. is Chairman of the Tribal Council of the Confederated Tribes of the Warm Springs Reservation of Oregon.
Shannon F. Wheeler is Chairman of the Tribal Executive Committee of the Nez Perce Tribe.