Welcome to the Hot Water Report 2024: Warming Waters in the Lower Snake and Columbia Rivers.
I. EXECUTIVE SUMMARY
- Since the completion of the dams on the lower Snake River, salmon and steelhead have returned annually far below the recovery goals necessary to remove them from the protections of the Endangered Species Act and to achieve healthy and abundant levels.
- This week, on the lower Snake River, three reservoirs have registered high temperatures above the 68°F “harm” threshold. The reservoir behind the Little Goose Dam registered the highest water temperature of 69.53°F on July 9.
- Given the current returns for wild Snake River Spring/Summer Chinook, steelhead, and sockeye, these fish have reached quasi-extinction thresholds – a critical threshold signaling they are nearing extinction, and without effective near-term intervention, many may not persist.
II. INTRODUCTION
The once-abundant anadromous fish populations of the Columbia-Snake River Basin are on the brink of extinction today due primarily to harm 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 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, three reservoirs have registered high temperatures above the 68°F “harm” threshold. The reservoir behind the Little Goose Dam registered the highest water temperature of 69.53°F on July 9. In Issue 3, we’ll explore historical and 2023 wild Snake River salmon and steelhead returns and compare recent returns to established recovery goals – the annual adult returns deemed necessary to recover these populations and remove them from the Endangered Species Act list and achieve healthy and abundant levels.
Since the four lower Snake River dams were built over 60 years ago, Snake River salmon and steelhead returns have declined and remained far below the recovery goals necessary to sustain them over time and to remove them from the Endangered Species Act list and to achieve healthy and abundant levels. Without immediate and meaningful conservation actions, many scientists anticipate we will lose these fish forever.
During the summer, the Hot Water Report will provide real-time water temperatures in the lower Snake and Columbia river reservoirs, with updates and reports from scientists, Tribal members, fishing guides, and other experts about the challenges facing these rivers and our opportunities to recover healthy, resilient fish populations and the benefits they deliver to Northwest communities, and other fish and wildlife populations.
View the Hot Water Report issues at wildsalmon.org/HWR
III. READING THE DATA - LOWER SNAKE AND COLUMBIA RIVER TEMPERATURES
INTRODUCTION TO THE WATER TEMPERATURE DATA:
- Throughout this summer, the Hot Water Report will provide, on a weekly basis, an update on real-time water temperatures in the lower Snake and Columbia River reservoirs.
- The daily average and high water temperature data at the four reservoir forebays are measured with sensors stationed at various depths below the reservoir surface, immediately upstream from the dams in the lower Snake River and the lower Columbia River for 2024.
- Average Water Temperature Graphs: Daily average temperatures are represented with solid lines and the 10-year average (2014 - 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.
- Weekly High Water Temperature Tables: This table outlines the highest water temperatures reported for each reservoir during the week and how many days water temperatures have exceeded 68°F.
- 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.
IV. DISCUSSION OF DATA - LOWER SNAKE AND COLUMBIA RIVER TEMPERATURES
LOWER SNAKE RIVER AVERAGE TEMPERATURES: 7/3 - 7/10
- Lower Snake River Water Temperatures: this week, the reservoir behind the Lower Monumental reservoir reached a high average water temperature of 68.30°F on July 10.
- The Little Goose Dam reached an average water temperature of 68.28°F on July 9 and has reached over their 10-year average of 67.40°F. The Ice Harbor reservoir reached an average temperature of 68.03°F on July 10. While average temperatures in the Lower Granite reservoir have not reached 68°F due to the US Army Corps of Engineers releasing cold water from the Dworshak Reservoir in the Clearwater River (see more info below), we expect these temperatures will rise considerably in these reservoirs in the upcoming weeks.
WEEKLY HIGH TEMPERATURES IN THE LOWER SNAKE RIVER: 7/3 - 7/10
- This week, on the lower Snake River, three reservoirs have registered high temperatures above the 68°F “harm” threshold. The reservoir behind the Little Goose Dam registered the highest water temperature of 69.53°F on July 9.
- Both Ice Harbor and the Lower Monumental Dam reservoirs registered the second highest water temperature of 68.72°F on July 10.
As air temperatures are increasing to near 100°F, the US Army Corps of Engineers announced their mitigation effort to release cold water from the Dworshak Reservoir in the Clearwater River (a tributary to the lower Snake River) to lower water temperatures and aid salmon migration in the lower Snake River. However, the benefits of this cold water infusion are limited. The presence of the dams prevents this cold water from entering the three downstream reservoirs. With a free-flowing lower Snake River, the additional benefit of cold waters released from the Dworshak reservoir will extend down the lower Snake River to its confluence with the Columbia River.
LOWER COLUMBIA RIVER AVERAGE TEMPERATURES: 7/3 - 7/10
- Lower Columbia River Water Temperatures: this week, three reservoirs on the lower Columbia River reached water temperatures above the 68°F “harm” threshold. The reservoir behind the John Day Dam had a high average temperature of 69.62°F on July 9, exceeding its 10-year average temperature of 68.10°F.
- The Bonneville Dam reservoir reached a high average temperature of 69.08°F on July 9 and reached above its 10-year average temperature of 68°F. The Dalles reservoir reached a high water temperature of 68.54°F. The reservoir behind the McNary Dam has not yet reached the 68°F threshold.
WEEKLY HIGH TEMPERATURES IN THE LOWER COLUMBIA RIVER: 7/3 - 7/10
- On the lower Columbia River, the John Day reservoir registered the highest water temperature at 70.70°F. The lower Columbia River water temperatures exceeding 68°F imperils salmon and steelhead as they migrate through the stagnant reservoirs created by federal dams to reach the ocean and again on their journey back upstream as adults.
Data Sources: The 2024 lower Snake River and lower Columbia River water temperature data presented in the Hot Water Report are collected from the USGS, 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. Lower Monumental 10-year average water temperatures are unavailable. Graphs and tables are assembled by SOS Staff.
V. Restoring Healthy and Abundant Snake River Wild Salmon & Steelhead
The Snake River's anadromous fish populations have been on a steady downward trajectory for decades. These salmon and steelhead face multiple obstacles, including increasingly hot water in the summer months in both the lower Snake and Columbia river reservoirs. Below, we present background information on the status of native fish returns, including (1) wild/natural Snake River sockeye (2) wild Snake River Spring/Summer Chinook, (3) wild steelhead. We will also look at how the historical and 2023 adult returns compare to established recovery goals – the annual adult fish returns deemed necessary to recover these populations to abundance and remove them from the Endangered Species Act list.
In summary - since the four lower Snake River dams were built, over 60 years ago, Snake River salmon and steelhead populations have steadily declined. Long before the dams were constructed, scientists projected the lower Snake River dams would devastate the last remaining robust wild salmon and steelhead population returning to the basin. Over the past several decades, these fish have returned annually far below the recovery goals necessary to remove them from the protections of the Endangered Species Act. Without immediate and meaningful conservation actions, scientists predict these populations will continue their decline toward extinction.
A. What Are Wild Salmon and Steelhead Returns?
The size and condition of a given population of salmon or steelhead are typically measured by the number of adult fish that return from the ocean to their upriver spawning grounds each year. The most straightforward method to measure the size of a salmon run is to count the fish as they swim upstream.
Snake River salmon and steelhead runs are counted at Lower Granite Dam, the last impediment on the river before the fish enter thousands of miles of tributary spawning and rearing habitat in central Idaho, Oregon, and Washington. Salmon returns have been counted on the lower Snake River since Ice Harbor Dam was first completed in 1962. This dataset of 60+ years, coupled with informed estimates of run sizes before the dams were constructed, provides valuable insight into the precipitous declines wild salmon and steelhead have experienced in the last 4-5 decades.
B. Historical Context
Historical data for the Columbia and Snake rivers indicate that 10-16 million wild adult salmon and steelhead entered the Columbia River Basin to spawn annually, with 2-6 million more utilizing the Snake River watershed.1 The health of these populations has plummeted over time from historic levels that were once in the hundreds of thousands or millions, depending on the particular population.
Any enthusiasm today about a modest uptick in adult returns in a given year is a symptom of what scientists call “the shifting baseline syndrome,” where the perception of what constitutes a healthy population is based only on very recent reference points. These benchmarks today are extraordinarily low due to steep, long-term population declines. The result is that our collective perception of what constitutes a healthy salmon return continually shifts downward. Put simply, since the completion of the dams on the lower Snake River, nearly half of Snake River salmon and steelhead populations have reached quasi-extinction thresholds – a critical threshold signaling they are nearing extinction, and without immediate or near-term intervention, many may not persist, according to Nez Perce Tribe fishery scientists.
C. Recovery Goals for Healthy, Abundant, and Harvestable Salmon and Steelhead Populations
Recovery goals for wild Snake River salmon and steelhead have been set to reflect the healthy runs that returned to Idaho in the 1950s – before the dams were constructed. These goals represent self-sustaining, harvestable populations that scientists have determined the currently available, high-quality habitat in the Snake River Basin can support.
In 2020, the Columbia Basin Partnership - a diverse group of 31 Columbia Basin stakeholders and sovereigns, including Columbia Basin Tribes; representatives of the four Columbia Basin states (Washington, Oregon, Idaho, and Montana); ports, hydropower interests and public power entities; irrigators; transportation representatives; commercial and recreational fishers and conservationists convened by NOAA - released a set of recovery goals and common vision for the Basin and its salmon and steelhead to ensure that healthy runs of salmon and steelhead thrive into the future.
The Partnership unanimously defined “recovery” to mean healthy, abundant, and harvestable naturally reproducing populations of salmon and steelhead. To achieve cultural and economic stability provided by healthy salmon and steelhead stocks, many more naturally produced fish are needed to meet the recovery goals established by the Partnership – roughly five times the number needed to lift Endangered Species Act protections.2
Restoring the lower Snake River through dam removal is our most significant river and salmon restoration opportunity anywhere in the nation today. A restored, healthy and resilient lower Snake River is necessary to uphold our nation's promises to Tribes and restore healthy and abundant salmon and steelhead for future generations by reconnecting this emblematic fish to 5,500 miles of pristine, protected river and streams in Idaho, Oregon, and Washington.
D. Current Status of Wild Snake River Salmon and Steelhead Returns
(1) Snake River Sockeye:
- Endangered Species Act Status: Endangered (listed in 1991)
- Historical Annual Return: Over 84,000
- Recovery Goal: 9,000 wild adults per year to the Stanley Basin
- 2023 Wild Returns: 31 wild/natural-origin sockeye returned to the Stanley Basin
Analysis: Historic runs to Idaho’s high mountain lakes used to be over 84,000+ sockeye per year, but they have severely declined over the years. In 1991, the Shoshone-Bannock Tribes successfully petitioned the federal government to list the run under the Endangered Species Act - making Snake River Sockeye the first ESA-listed salmonid in the Columbia Basin. According to the Idaho Fish and Game, in 1991, only four adult sockeye returned to the Sawtooth Basin. 23 sockeye returned between 1991-99, including two years when no sockeye returned.3
Snake River Sockeye have greater exposure to higher temperatures because they migrate in the summer when temperatures are hottest. In 2021, only 4 wild adult sockeye salmon survived and reached their spawning grounds in the Stanley Basin in central Idaho, after struggling past eight dams and warm, stagnant reservoirs.
In 2023, the Washington and Oregon Department of Fishery and Wildlife jointly reported a total Snake River Sockeye entering the Columbia was 1,999. Only 31 wild/natural Snake River Sockeye actually reached the Sawtooth Valley lakes (a unique and irreplaceable spawning ground for Snake River Sockeye).
Due to heat stress from hot water temperatures in the reservoirs of the lower Columbia and Snake rivers in 2023, 91% of the returning adult Snake River Sockeye that entered the mouth of the Columbia River died before spawning. Fishery scientists are predicting a similar decline of sockeye returns this year as a result of low returns entering the Columbia River and hot water temperatures in the lower Columbia and Snake Rivers.
At the beginning of July 2024, Oregon and Washington fisheries managers closed recreational fishing for all Columbia Basin sockeye in order to eliminate fishing impacts and protect ESA-listed Snake River Sockeye. The extremely depleted Snake River Sockeye are constraining important, valuable fishing opportunities in the lower Columbia River this summer where they are mixed with other, considerably more robust salmon populations that are running upstream at the same time. Snake River Sockeye are mixing in the lower Columbia River with a surprisingly robust return of adult sockeye swimming up the Columbia River to the Okanagon and Wenatchee Rivers. The initial pre-season forecast for these sockeye was 407,100, but was recently doubled by fisheries managers. In sharp contrast, the predicted return of Snake River Sockeye this year to the mouth of the Columbia River is just 3,800. Very few of these fish will survive to reach their spawning gravels high in the Stanley Basin of central Idaho.
(2) Snake River Spring/Summer Chinook:
- Endangered Species Act Status: Threatened (listed in 1992)
- Historical Annual Return: Over 1.5 million
- Recovery Goal: Escapement of 138,000 wild adults per year
- 2023 Wild Returns: 8,028
- Analysis: Spring/Summer Chinook were once the Pacific Northwest’s most widely distributed and abundant salmon, numbering in the millions. In the past five years, wild Snake River Spring/Summer Chinook numbers averaged less than half of their total return when the fish were first listed under the ESA in 1992. Snake River Spring/Summer Chinook remain far from the recovery goal (a minimum of 127K annually), and the population remains in long-term decline and at risk of extinction.4
(3) Snake River Steelhead:
- Endangered Species Act Status: Threatened (listed in 1997)
- Historical Annual Return: An estimated 600,000
- Recovery Goal: Escapement of 112,500 wild adults per year
- 2022/23 Returns: 13,631
- Analysis: The Snake River and its tributaries produced 55 percent of summer steelhead in the entire Columbia River Basin.5 However, today, wild steelhead are returning well below their recovery goal.
Given the current returns for wild Snake River Spring/Summer Chinook, steelhead, and sockeye, these fish are much closer to extinction than recovery. Each year, salmon and steelhead are returning far, far below their historical and recovery levels.
The four federal dams and their reservoirs on the lower Snake River continue to be the main obstacle to recovery. The rising temperatures caused by these stagnant reservoirs 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.
Restoring this historic salmon river is essential for protecting these fish from extinction and rebuilding the many benefits they provide for the people of the Northwest and our nation.
Data Sources for the Idaho Rivers United’s ‘Snake River Wild Salmon Returns’ report: Fish Passage Center, Idaho Department of Fish and Game, and the Columbian Basin Partnership. Idaho Rivers United staff assembled the tables and graphs.
References:
1. Orca Action Month: Exploring the History of Salmon in the Columbia and Snake River Systems
2. Trout Unlimited: What does salmon and steelhead “recovery” mean and who decides?
3, 5. The Salmon Community’s View: The status of wild salmon and steelhead populations in the Columbia and Snake River Basin
4. Spokesman-Review: Helen Neville: The need to breach the Lower Snake River dams: A look at 2022 fish returns
The Hot Water Report is a joint project of the Save Our wild Salmon Coalition, Association of Northwest Steelheaders, Columbia Riverkeeper, Earthjustice, Endangered Species Coalition, Idaho Conservation League, Idaho Rivers United, National Wildlife Federation, Natural Resources Defense Council, Northwest Sportfishing Industry Association, Orca Network, Sierra Club, Snake River Waterkeeper, and Wild Steelhead Coalition.
View previous Hot Water Report issues at wildsalmon.org/HWR