Restoring the Lower Snake River

Restoring the Lower Snake River

HWR Banner sockeye salmon with lesions image by Conrad Gowell Sockeye salmon with lesions dying from hot water in the Columbia-Snake River Basin © Conrad Gowell
Welcome to the Hot Water Report 2024: Warming Waters in the Lower Snake and Columbia Rivers.

I. EXECUTIVE SUMMARY

Historically, the three Southern Resident orca pods – J, K, and L pods – have fed on an abundance of large, fatty Chinook salmon.
Southern Resident orcas are listed as endangered in both the U.S. (listed in 2005) and Canada (listed in 2003). The lack of Chinook salmon is the single greatest threat to the survival of the Southern Resident orcas. Only 74 individual orcas survive today (according to the Center for Whale Research’s annual census of the Southern Resident population completed in January 2024).
Snake River Spring/Summer Chinook and Snake River Fall Chinook as well as many Columbia-Basin salmon runs are ranked in the top 10 Priority Chinook stocks for orca recovery.
Research conducted by Orca Behavior Institute, shows how abundant food sources are key to healthy orca populations. Similar to Bigg’s orcas recovery, with enough food, Southern Residents would be able to overcome threats, live healthier lives with their pods, and grow in population size.
Scientists agree that recovering Chinook salmon is essential for the recovery of Southern Residents. Key actions to help achieve abundant salmon include removing the four lower Snake River dams to restore Snake River salmon runs, restoring salmon habitats across the Columbia-Snake River Basin, and protecting marine habitats in order to increase Southern Residents’ ability to reproduce and increase their survival rate.

II. INTRODUCTION

Mollie Brown Breaking the Surface 2024 Breaking the Surface, 2024 © Mollie Brown

Before the lower Snake River dams were built, the pristine, clear, cold waters of the Snake River Basin were home to millions of adult salmon and steelhead, along with sturgeon, lamprey eel, and other native fishes. The once-abundant anadromous fish populations in the Columbia-Snake River Basin (fish that hatch in freshwater, go to sea, and return to freshwater to spawn) are struggling to survive today primarily due to harms caused by the federal dams and their warming 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 in the summer months. These cold-water fish begin to suffer harmful effects when water temperatures exceed 68° Fahrenheit.

Columbia-Snake River Basin salmon and steelhead populations are rapidly declining, and Southern Residents are also facing extinction due to a lack of their main food source–Chinook salmon. Only 74 individual orcas survive today. In Issue 11, we will report on Southern Resident orcas and the urgency to restore the lower Snake River through dam removal to bring salmon back to abundance along with restoring salmon habitats across the Columbia-Snake River Basin, and protecting marine habitats in order to protect Southern Residents from extinction.

During the summer, our Hot Water Report provides 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, 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.
Hot water temperature effects to salmon: The longer and the higher water temperatures rise above 68°F "harm" threshold, the greater the harm to salmon, 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.
Data collection: 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. The water temperatures are taken on the hour. Hourly temperatures are used to find the highest temperatures reached in each reservoir, and hourly temperature measurements are used to find the daily average temperatures.
Average Water Temperature Graphs (below): Daily average temperatures are represented with solid lines, and the 10-year average (2014 - 2023) temperatures are 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 (below): This table outlines the highest water temperatures reported for each reservoir during the week and how many days water temperatures have exceeded 68°F.

IV. DISCUSSION OF DATA - LOWER SNAKE AND COLUMBIA RIVER TEMPERATURES

LOWER SNAKE RIVER WATER TEMPERATURES: 8/30 - 9/7

Lower Snake River Water Temperatures - 2024 Daily Average and 10-year Average. Click on the image to view the graph and click here to view the PDF version with separate graphs for each reservoir.

Lower Snake River - 2024 Daily Average and 10-year Average.

Lower Snake River Water Temperatures: this week, the Ice Harbor Dam's reservoir experienced a high average water temperature of 69.49°F on August 30.
The Lower Monumental Dam's reservoir registered a high average temperature of 68.30°F on September 5.
The Little Goose Dam’s reservoir registered an average temperature of 67.94°F on August 30.
The Lower Granite Dam's reservoir registered an average of 67.38°F. Lower Granite Dam’s reservoir’s average and high daily temperatures registered below 66°F due to the US Army Corps of Engineers’ continued cold water release effort from the reservoir behind Dworshak Dam’s Reservoir in the Clearwater River, a tributary to 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 in south-central Washington State.

WEEKLY HIGH TEMPERATURES IN THE LOWER SNAKE RIVER: 8/30 - 9/7

Many of the lower Columbia and Snake river reservoirs continue to reach above the 68°F “harm” threshold, for over 60 days.
The Ice Harbor Dam's reservoir registered the highest temperature of 69.62°F on August 30.
Lower Monumental Dam’s reservoir registered a high water temperature of 68.45°F on September 5.
The Little Goose Dam's reservoir reached the highest water temperature of 68.56°F on September 5.
The Lower Granite Dam's reservoir registered a high water temperature of 67.91°F.
Water temperatures in the Lower Monumental Dam’s reservoir has exceeded 68°F for 61 days, Ice Harbor Dam's reservoir has exceeded 68°F for 60 days, and Little Goose Dam's reservoirs have exceeded 68°F for 56 days.

LOWER COLUMBIA RIVER WATER TEMPERATURES: 8/30 - 9/7

Lower Columbia River - 2024 Daily Average and 10-year Average.

Lower Columbia River Water Temperatures - 2024 Daily Average and 10-year Average. Click on the image to view the graph and click here to view the PDF version with separate graphs for each reservoir.

Lower Columbia River Water Temperatures: this week, all four reservoirs on the lower Columbia River exceeded 68°F.
The reservoir behind John Day Dam had a high average temperature of 70.34°F on September 7. The reservoir behind The Dalles Dam reached an average temperature of 69.98°F on September 6 and 7.

WEEKLY HIGH TEMPERATURES IN THE LOWER COLUMBIA RIVER: 8/30 - 9/7

This week, on the lower Columbia River, the John Day Dam’s reservoir reached the highest temperature at 70.88°F.
Bonneville Dam reservoir has spent 64 consecutive days above 68°F, and both The Dalles Dam and John Day Dam reservoirs registered above 68°F for 63 days.

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. Critically endangered Southern Resident orcas need more Chinook salmon

K25 with a salmon © Monika Wieland Shields

Highly social and intelligent Southern Resident orcas have roamed the coastal waters of the Pacific Northwest and have held cultural and spiritual significance for Northwest Tribes since time immemorial. The three Southern Resident orca pods – J, K, and L– have historically fed on an abundance of large, fatty Chinook salmon. However, today, Columbia-Snake River Basin Chinook salmon populations are rapidly declining, and Southern Residents are also facing extinction due to a lack of food. Only 74 individual orcas survive today (according to the Center for Whale Research’s annual census of the Southern Resident population completed in January 2024).

Scientists agree there is an urgent need to remove the four lower Snake River dams to restore Snake River salmon runs, restore salmon habitats across the Columbia-Snake River Basin, and protect marine habitats in order to increase Southern Residents’ ability to reproduce and increase their survival rate.

Who are the Southern Residents orcas?

The three Southern Resident orca pods, known as J, K, and L pods, are a genetically and culturally distinct population unlike other orca communities found within the Pacific Northwest. Southern Residents communicate using their own exclusive dialect, typically traveling in large, extended family groups led by matriarchs, and stay in these extended family groups their entire lives. Historically, Southern Residents traveled, foraged, and socialized throughout the inland waters of the Salish Sea from late spring through late summer feeding on Chinook salmon.¹

Columbia-Snake River Basin salmon importance to Southern Resident orcas

L84 with a salmon Sept. 29 2011. Photo by Dave Ellifrit of the Center for Whale Research

Southern Residents are the original fishers of the Pacific Northwest waters, co-evolving over millennia with their preferred prey, Chinook salmon. Chinook salmon are the primary food source for the endangered Southern Residents, accounting for 50%-100% of their diet depending on the season. The Columbia-Snake River Basin and the Fraser River are the two most important sources of salmon for these orcas, where Columbia-Snake River Basin Chinook salmon account for more than half of the Chinook consumed by the orcas during the winter while they’re in coastal water.²

Southern Resident orcas are listed as endangered in both the U.S. (listed in 2005) and Canada (listed in 2003). The lack of Chinook salmon is the single greatest threat to the survival of the Southern Resident orcas. In 2016, the National Oceanic and Atmospheric Administration (NOAA) identified Southern Resident orcas as one of eight species most likely to go extinct in the near future unless immediate action is taken.

Data from the Center for Whale Research has shown that Southern Resident mortality is correlated with coast-wide Chinook salmon abundance. Drone research from SR3 has shown that Southern Residents are sometimes visibly thin, and a study from the U.W. Conservation Canine program discovered a 69% miscarriage rate primarily due to lack of food. This research indicates that restoring salmon for Southern Residents should be our top priority.

In 2018, NOAA Fisheries and Washington Department of Fish and Wildlife (WDFW) developed a list of Chinook salmon stocks identified as important to Southern Residents’ survival and required priority actions to increase critical prey for these orcas. Snake River Spring/Summer Chinook and Snake River Fall Chinook, as well as many Columbia-Basin salmon runs, are ranked in the top 10 Priority Chinook stocks for orca recovery.

Despite years of recovery efforts to restore Southern Residents and salmon, they both teeter on the brink of extinction. As fewer salmon return to the ocean, these iconic orcas are starving, and their population has declined to a record low – only 74 individuals are alive today – 25 in J Pod, 15 in K Pod, and 34 in L Pod (according to the Center for Whale Research’s annual census of the Southern Resident population completed in January 2024).

Hope for Southern Residents informed by Bigg’s orcas' recovery journey

The Southern Residents and Bigg’s orcas frequent the same waters in the Salish Sea and along the Pacific Coast. They are still considered the same species but are different ecotypes, meaning they are two distinct types of orcas that differ in size, appearance, pod structure, diet, behavior, culture, acoustics, and genetics.^3,4

As much as they are different, Bigg’s orcas and Southern Residents encounter the same threats, including pollution, noise and disturbances, and both have a history of being captured for display, which all have impacted their population.

Both Bigg’s orcas (listed as threatened in Canada) and Southern Residents experience the same threats; however, Bigg’s are thriving, overcoming threats, and increasing in population size. Why?

Research conducted by Orca Behavior Institute shows how abundant food sources are key to healthy orca populations, and with enough food, they are able to overcome threats and live healthier lives.

The Southern Residents have a very long history and knowledge of foraging for salmon in the Salish Sea and along the Pacific Coast, where Columbia-Snake River Basin Chinook salmon account for more than half of the Chinook provide Southern Residents’ winter diet.⁵

Since the decline of Chinook salmon, each of the Southern Resident pods have shifted their presence along their historical foraging range based on Chinook salmon runs.^6,7 According to Orca Behavior Institute data with reports from Pacific Whale Watch Association, Orca Network, and other sighting groups and community scientists, there was a 24% decline in Southern Resident sightings in 2023 compared to 2022, with a particularly noticeable drop in the summer and fall. 20 years ago, the Southern Residents were spending an average of more than 80 days in the Salish Sea in the months of June through August. For 2019-2023, that average has dropped to just 20 days.

For Southern Residents, the lack of salmon is by far the single greatest threat to their survival. For example, in the context of encountering pollution, when Southern Residents are not getting enough to eat, they are more susceptible to metabolizing their fat stores, releasing pollutants that circulate through their body, which makes them immune compromised.⁸With the pollutants and lack of food in their bodies, it makes it harder to forage for food, and overall their quality of life declines.

In contrast, Bigg's absorb more toxins because the food (seals and seal lions) they eat are higher in the food web, but they are still healthier because they get enough to eat and therefore don't need to metabolize fat stores. Bigg’s population size continues to double due to finding enough food, and have been increasingly using the Salish Sea over the last 30 years, as shown in the annual Bigg’s sighting map above, where a total of 1413 sightings of Bigg’s were seen in 2023.

Contrasting the Bigg’s and Southern Resident maps shows us that when we restore Chinook salmon for Southern Residents, they can live healthier longer lives and thrive similar to Bigg’s orcas, despite other threats they encounter.

Restoring a free-flowing lower Snake River to recover Southern Resident orcas and salmon

Britt Freda Tahlequahs Respair J35 and J57 Tahlequah's Respair J35 and J57 © Britt Freda

Since time immemorial, Southern Residents have a deep interconnected relationship with salmon, in which salmon has heavily influenced Southern Residents’ culture, communication, and genetics.

However, today, orcas are finding less and less salmon in their traditional and historical foraging areas, causing Southern Residents significant stress about finding enough food for their pod and often becoming visibly thin. Their mortality is linked to not having enough Chinook salmon as well as not having enough strength to overcome other threats that they face.

Scientists have identified that Snake River salmon are among the priority Chinook salmon that are essential to the recovery of Southern Residents. It is critical for Southern Residents to feed on salmon throughout their entire foraging range and also throughout the entire year, especially in the winter and early spring when orcas move toward the mouth of the Columbia Basin.

Scientists agree that recovering Chinook salmon is essential for the recovery of Southern Residents. Key actions to help achieve abundant salmon include removing the four lower Snake River dams to restore Snake River salmon runs, restoring salmon habitats across the Columbia-Snake River Basin, and protecting marine habitats in order to increase Southern Residents’ ability to reproduce and increase their survival rate.

References:
1.Orca Action Month: Orca Facts
2, 5. Hanson MB, Emmons CK, Ford MJ, Everett M, Parsons K, Park LK, et al. (2021) Endangered predators and endangered prey: Seasonal diet of Southern Resident killer whales. PLoS ONE 16(3): e0247031. https://doi.org/10.1371/journal.pone.0247031
3. Whale and Dolphin Conservation: Meet the different types of orcas
4. Orca Conservancy: The killer whales of the Pacific Northwest
7. Shields MW. 2023. 2018–2022 Southern Resident killer whale presence in the Salish Sea: continued shifts in habitat usage. PeerJ 11:e15635 https://doi.org/10.7717/peerj.15635
8. Wild Orca (2022) Hot Water Report: Interview with Dr. Deborah Giles - Science and Research Director at Wild Orca

The Hot Water Report is a 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

I. EXECUTIVE SUMMARY

Returning adult Snake River salmon and steelhead are struggling today to migrate through harmful/potentially lethal water temperatures in the lower Snake and Columbia rivers. As of August 29, many of the reservoirs have approached over 50 days above 68°F “harm” threshold.
The four federal dams and their hot water reservoirs on the lower Snake River continue to be a major driver of salmon and steelhead mortality and heat pollution on the lower Snake River.
For decades, federal agencies have long resisted any meaningful action to reduce the dams’ water temperature pollution. Columbia Riverkeeper and many others have used science and the Clean Water Act to increase pressure on the U.S. Army Corps of Engineers (Corps) to reduce heat pollution caused by the lower Snake River dams.
Despite the Corps’ attempts to ignore potential solutions that keep the lower Snake River dams and reservoirs from warming to levels that kill endangered salmon, the Washington Department of Ecology recently used its Clean Water Act authority to require the Corps to study all possible ways to cool the lower Snake River.

II. INTRODUCTION

'Columbia Meets The Pacific' 40x60 © Rachel Teannalach

In Issue 10, 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 and enable their recovery. 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 decades. Now, directed by the Department of Ecology, the U.S. Army Corps of Engineers must put forward a new plan that examines all possible ways to cool the lower Snake River and reduce heat pollution.

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.
Hot water temperature effects to salmon: The longer and the higher water temperatures rise above 68°F "harm" threshold, the greater the harm to salmon, 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.
Data collection: 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. The water temperatures are taken on the hour. Hourly temperatures are used to find the highest temperatures reached in each reservoir, and hourly temperature measurements are used to find the daily average temperatures.
Average Water Temperature Graphs (below): Daily average temperatures are represented with solid lines, and the 10-year average (2014 - 2023) temperatures are 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 (below): This table outlines the highest water temperatures reported for each reservoir during the week and how many days water temperatures have exceeded 68°F.

IV. DISCUSSION OF DATA - LOWER SNAKE AND COLUMBIA RIVER TEMPERATURES

LOWER SNAKE RIVER WATER TEMPERATURES: 8/24 - 8/29

Lower Snake River - 2024 Daily Average and 10-year Average.

Lower Snake River Water Temperatures: this week, the Ice Harbor Dam's reservoir experienced a high average water temperature of 70.64°F on August 24.
The Lower Monumental Dam's reservoir registered a high average temperature of 69.42°F on August 24.
The Little Goose Dam’s reservoir registered 68.52°F on August 26.
The Lower Granite reservoir registered a high average of 67.31°F. Lower Granite Dam’s reservoir’s average and high daily temperatures registered below 67°F due to the US Army Corps of Engineers’ continued cold water release effort from the reservoir behind Dworshak Dam. Unfortunately, these cold water releases do not significantly cool/benefit the three downstream reservoirs on the lower Snake River.

WEEKLY HIGH TEMPERATURES IN THE LOWER SNAKE RIVER: 8/24 - 8/29

Many of the lower Columbia and Snake river reservoirs continue to reach above the 68°F “harm” threshold, for over 50 days.
The Ice Harbor Dam's reservoir registered the highest temperature of 70.77°F on August 24.
Lower Monumental Dam’s reservoir registered a high water temperature of 69.58°F on August 24.
The Little Goose Dam's reservoir reached the highest water temperature of 68.85°F on August 26. The Lower Granite Dam's reservoir registered a high water temperature of 68.18°F.
Water temperatures in the Ice Harbor Dam reservoir have exceeded 68°F for 51 consecutive days. Lower Monumental Dam’s reservoir have exceeded 68°F for 53 days and Little Goose Dams’ reservoirs have exceeded 68°F for 52 days.

LOWER COLUMBIA RIVER WATER TEMPERATURES: 8/24 - 8/29

Lower Columbia River - 2024 Daily Average and 10-year Average.

Lower Columbia River Water Temperatures - 2024 Daily Average and 10-year Average. Click on the image to view the graph and click here to view the PDF version with separate graphs for each reservoir

Lower Columbia River Water Temperatures: this week, all four reservoirs on the lower Columbia River exceeded 68°F.
The reservoir behind John Day Dam had a high average temperature of 69.98°F on August 29. The reservoir behind The Dalles Dam reached an average temperature of 69.80°F on August 27.

WEEKLY HIGH TEMPERATURES IN THE LOWER COLUMBIA RIVER: 8/24 - 8/29

This week, on the lower Columbia River, John Day Dam's reservoir reached the highest temperature at 70.52°F.
Bonneville Dam reservoir has spent 55 consecutive days above 68°F and both The Dalles Dam and John Day Dam reservoirs registered above 68°F for 54 days.

V. Progress for Cold Water
How the Clean Water Act is forcing the Army Corps to get serious about reducing heat pollution from the Lower Snake River reservoirs

By Miles Johnson, Legal Director for Columbia Riverkeeper

'Snake River at Lewiston' 36x48 © Rachel Teannalach

Good news for fish and fans of cold water: the Washington Department of Ecology recently used its Clean Water Act authority to require the Army Corps to study all possible ways to cool the lower Snake River!

The Clean Water Act is America’s flagship law protecting healthy streams, rivers, and lakes. Enacted when some of our nations’ 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 caused by dams on the lower Snake and Columbia rivers? In theory, the answer is yes, but federal agencies have long resisted any meaningful action to reduce the dams’ temperature pollution. So for the last decade, Columbia Riverkeeper and many others have used science and the Clean Water Act to increase pressure on the U.S. Army Corps of Engineers (Corps) to reduce the lower Snake River dams’ hot water pollution, also known as heat pollution.

Ecology’s recent decision is another important step toward that goal! Here’s a quick history of this issue:

2014: Columbia Riverkeeper sues the Corps for discharging oil and heat pollution into the lower Snake River without Clean Water Act Permits.
2015: 96% of adult endangered Snake River sockeye salmon die because of hot water in the lower Snake and Columbia rivers. Major temperature-related fish kills occur in the summers of 2013, 2021, and 2023.
2016: Columbia Riverkeeper and allies sue under the Clean Water Act to require EPA to create a pollution budget (called a Total Maximum Daily Load analysis, or TMDL) for heat pollution in the Columbia and lower Snake rivers.
2017: Columbia Riverkeeper uses computer modeling to show that, without the dams, the lower Snake River would be cool enough for salmon to migrate safely.
2019: Ninth Circuit Court of Appeals orders EPA to write a temperature specific Total Maximum Daily Load (TMDL) for the Lower Snake and Columbia Rivers.
2021: EPA releases a final temperature TMDL for the lower Snake and Columbia rivers. It identifies the dams and reservoirs as major sources of heat pollution, and sets numeric temperature reduction targets for each dam.
2022: As a result of Columbia Riverkeeper’s 2014 suit against the Corps, EPA finally issues Clean Water Act discharge permits for the Corps’ Lower Snake River dams. These permits require the Corps to make a plan (called a Water Quality Attainment Plan) to achieve the temperature reductions mandated by the TMDL.
April 2024: The Army Corps submits a Water Quality Attainment Plan for the lower Snake River reservoirs that does not propose any meaningful changes to meet the temperature limits.
March 2024: Columbia Riverkeeper and others submit comments to Ecology opposing the Corps’ inadequate temperature plan.
June 2024: Ecology formally rejects the Corps’ proposed plan and directs the Corps to put forward a new plan that examines all possible ways to cool the lower Snake River.

What’s next? The Corps must study ways to keep the dams and reservoirs from warming the lower Snake River to levels that kill endangered salmon. Despite the Corps’ attempts to ignore potential solutions—like drawing down reservoirs for part or all of the year—Ecology made clear that nothing is off the table when it comes to studying what could be done to keep the lower Snake River cool.

The Corps has until September 1, 2024, to submit a detailed new plan or explain to Ecology the Corps’ procedure for producing a new plan in cooperation with Ecology, EPA, Tribes, and others.

We are making steady progress, and we remain hopeful, but we still have a long road ahead. Studying and implementing ways to keep the river cool will take several years, and we fully expect the Corps to continue resisting meaningful actions that benefit salmon and steelhead. Nevertheless, we remain dedicated to delivering on the Clean Water Act’s promise of clean, healthy waterways with abundant fisheries resources.

Stay tuned for updated information and opportunities to advocate for a healthy river!

View previous Hot Water Report issues at wildsalmon.org/HWR

I. EXECUTIVE SUMMARY

Toxic algal blooms have re-emerged on the lower Snake River. Whitman County Public Health and the Washington State Toxic Algae Monitoring Program confirmed that the toxic algal bloom in the river tested positive for microcystins, which is a liver toxin harmful to people and the river ecosystem and lethal to pets.
For over 40 days, the lower Snake River has experienced hot water temperatures in which many of the reservoirs have continuously registered high temperatures between 70 - 72°F, well over the 68°F “harm threshold” –the biological and legal limit– set to protect migrating salmon and steelhead.
The warm water and stagnant reservoirs that toxic algal blooms thrive in are also harmful to salmon and steelhead. Toxic algal blooms are a health risk to people, pets, and the river; and significantly reduce what are already quite limited recreational and fishing opportunities on the lower Snake River.
Toxic algae is an additional stressor on already unhealthy and warming waters in the lower Snake River. By cooling down water temperatures and re-establishing currents, lower Snake River dam removal would reduce/eliminate toxic algal blooms, help restore a healthy river ecosystem that people can enjoy, and protect salmon and steelhead from extinction.

II. INTRODUCTION

Toxic algal blooms in the lower Snake River, October 2023 © LightHawk's pilot Dr. Judy Parrish

Before the lower Snake River dams were built, the pristine, clear, cold waters of the Snake River Basin were home to millions of adult salmon and steelhead, along with sturgeon, lamprey eel, and other native fishes. The once-abundant anadromous fish populations in the Columbia-Snake River Basin are struggling to survive today primarily due to harms caused by the 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 in the summer months. These cold-water fish begin to suffer harmful effects when water temperatures exceed 68° Fahrenheit.

In Issue 9, we report on toxic algal blooms recently found on the lower Snake River and tested positive for a liver toxin that is harmful to people and the river ecosystem and lethal to pets. These ‘blooms’ are visible across approximately 50 miles in two lower Snake reservoirs, and are expected to persist and expand in the months ahead.

During the summer, our Hot Water Report provides 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, 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. Confirmed: Toxic Algal Blooms Re-emerge on the Lower Snake River

Toxic algal bloom at Central Ferry on the Snake River, 2023 © Whitman County Public Health

Water samples taken in the lower Snake River on August 12 and August 16 tested positive for toxic algae with microcystins, a liver toxin that harms people and the river ecosystem and is lethal to pets. Whitman County Public Health collected a toxic algal bloom sample in the Lower Granite Dam’s reservoir near a popular recreational spot, Granite Point. The toxic algal bloom has been spotted in different areas covering a roughly 50-mile stretch of river between Nisqually John Landing in the Lower Granite Dam’s reservoir and Little Goose Dam.

Toxic algal blooms thrive in warm, nutrient-rich water

Cyanobacteria, a type of algae, occur naturally in freshwater environments and are vital to the function of aquatic ecosystems.¹ However, while cyanobacteria can be good, too much cyanobacteria in the water is dangerous. Excessive growth of this single-cell organism can lead to “blooms” that may cause serious harm to freshwater habitats and human and animal health, earning them the name “harmful algal blooms,” also referred to as toxic algal blooms.²

According to the Whitman County Public Health, some environmental factors that contribute to these algal blooms include: sunny days, warm water temperatures, still water conditions (or slow-moving stagnant water), and an influx of nutrients (namely nitrogen and phosphorous) that enters a waterbody via runoff or other sources. The combination of these conditions are most likely to materialize in late summer and early fall, when water and air temperatures are often at their highest (and precipitation and snowpack at their lowest).

Warm, slow-moving/stagnant, and nutrient-rich waters create ideal conditions to generate toxic algal blooms. For over 40 days, the lower Snake River has experienced hot water temperatures in which many of the reservoirs have continuously registered high temperatures between 70 - 72°F, over the 68°F “harm threshold” –the biological and legal limit– set to protect migrating salmon and steelhead. The water in the lower Snake River is already dangerously hot for salmon throughout every summer, and now it is providing conditions for toxic algae - causing the river to become unsafe and hazardous for people and pets.

On the lower Snake River, toxic algal blooms have occurred for the second year in a row, with a couple of instances in previous years. A large toxic algal bloom happened between September 2023 - January 2024, where the blooms were found in Granite Point, Wawawai Landing, Central Ferry, and Wawawai County Park. This year, toxic algal blooms have been found earlier - in mid-August - between Nisqually John Landing in the Lower Granite Reservoir and Little Goose Dam.

Impacts of toxic algal blooms on human health, pets, and aquatic life

823 toxic algal bloom samples by Whitman County Public Health Toxic algal bloom samples © Whitman County Public Health

When toxic algal blooms form, they usually appear as blue-green scum, foam, froth, or a paint-like slick on the water body’s surface.³ Under the right set of conditions (including factors like light intensity, nutrient loads, and water temperature and salinity), these cyanobacterial blooms can become toxic, producing byproducts known as cyanotoxins.⁴ Cyanobacteria can produce many cyanotoxins, such as microcystins, which were found on the lower Snake River in 2023 and now again this year in mid-August.

Microcystins are very stable and can withstand environmental forces (such as sunlight or temperature variations) without breaking down, which means this toxin can last up to several months under these “favorable” conditions.⁵ Microcystins are a group of toxins that can harm the liver and are commonly responsible for human and animal poisonings, and habitat degradation such as:

Impacts on human health: Direct exposure to water contaminated by Microcystin (via drinking, swimming, boating, fishing, or other activities that may lead to contact or accidental consumption) can cause these short-term health effects: headache, sore throat, vomiting, nausea, diarrhea, pneumonia, lethargy, skin rash, muscle cramping, and muscle twitching.^6,7 Long-term exposure effects include tumor development, liver failure, and decreased sperm count and motility.⁸

Impacts on domestic animals (primarily dogs): Direct exposure to water contaminated by Microcystin (via drinking, swimming, or licking fur that has been exposed) can cause these health effects in dogs and livestock: vomiting, diarrhea, weakness, pale gums, excessive drooling, paralysis, difficulty breathing, lethargy, skin rash, muscle cramping, muscle twitching, seizures, and sudden death from cyanotoxin poisoning.^9,10

Impacts associated with habitat degradation caused by algal blooms: Significant increases in algae harm water quality, food resources, and habitats, and decrease the oxygen that fish and other aquatic life need to survive – particularly upon the death of blooms when decomposing algae absorb large quantities of oxygen. This oxygen depletion can lead to injury and death in fish, especially resident species. Algal blooms also block sunlight that submerged aquatic vegetation needed to survive (and produce oxygen via photosynthesis), another way blooms deplete oxygen in freshwater systems.¹¹

Restoring a free-flowing and cold lower Snake River to protect communities, ecosystems, and salmon

© Neil Ever Osborne

The lower Snake River dams create reservoirs with warm slackwater that is harmful or lethal for salmon throughout the summer. And now things are getting worse: these same reservoirs are now becoming a breeding ground for toxic algal blooms, adding yet a new threat to endangered native fish and communities along the lower Snake River.

A sick lower Snake River, where toxic algal blooms are a regular occurrence, increases the pressures on threatened and endangered salmon and steelhead. Already under stress as they migrate through the dams’ warm reservoirs, these coldwater fish must now also contend with toxic algal bloom-driven oxygen depletion and changes in pH – at the same time that the reservoirs are at their hottest.

Removing the four lower Snake River dams will once again allow cool waters to flow freely and support healthy salmon populations. It will also mean far fewer toxic algal blooms and a healthier Snake River overall – one that benefits fish, people, communities, watersheds, and cultures.

Resources:

Toxic Algal Bloom Factsheet by Whitman County Public Health

References:
1,2, 4,6,8 Harmful Algal Blooms (HABs) in Water Bodies, U.S. Environmental Protection Agency; webpage accessed on April 23, 2024.
3, 5, Toxic Algae Blooms, Benton-Franklin Health District; webpage accessed on April 25, 2024.
7,9 Toxic Algal Blooms website by Whitman County Public Health
10. CDC: For Veterinarians: Harmful Algal Bloom-Associated Illnesses
11. Nutrient Pollution: Dead Zones and Harmful Algal Blooms, U.S. Environmental Protection Agency; webpage accessed on April 28, 2024.

IV. 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.
Data collection: 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. The water temperatures are taken on the hour. Hourly temperatures are used to find the highest temperatures reached in each reservoir, and hourly temperature measurements are used to find the daily average temperatures.
Average Water Temperature Graphs (below): Daily average temperatures are represented with solid lines, and the 10-year average (2014 - 2023) temperatures are 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 (below): This table outlines the highest water temperatures reported for each reservoir during the week and how many days water temperatures have exceeded 68°F.
Hot water temperature effects to salmon: The longer and the higher water temperatures rise above 68°F, the greater the harm to salmon, 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.

V. DISCUSSION OF DATA - LOWER SNAKE AND COLUMBIA RIVER TEMPERATURES

LOWER SNAKE RIVER WATER TEMPERATURES: 8/17 - 8/23

Lower Snake River - 2024 Daily Average and 10-year Average.

Lower Snake River Water Temperatures - 2024 Daily Average and 10-year Average. Click on the image to view the graph and click here to view the PDF version with separate graphs for each reservoir.

Lower Snake River Water Temperatures: this week, the Ice Harbor Dam's reservoir reached a high average water temperature of 71.00°F on August 22.
The Lower Monumental Dam's reservoir registered a high average temperature of 70.71°F on August 18.
The Little Goose Dam’s reservoir registered 70.48°F on August 17.
The Lower Granite reservoir registered a high average of 67.37°F. Lower Granite Dam’s reservoir’s average and high daily temperatures registered below 67°F due to the US Army Corps of Engineers’ continued cold water release effort from the reservoir behind Dworshak Dam. However, these cold water releases do not significantly cool/benefit the three downstream reservoirs on the lower Snake River.

WEEKLY HIGH TEMPERATURES IN THE LOWER SNAKE RIVER: 8/17 - 8/23

The lower Columbia and Snake river reservoirs continue to reach above the 68°F “harm” threshold. This week, many of the reservoirs’ temperatures ranged between 70°F - 71°F.
The Little Goose Dam's reservoir reached the highest water temperature of 71.73°F on August 17. Lower Monumental Dam’s reservoir registered a high water temperature of 71.31°F on August 17.
The Ice Harbor Dam's reservoir registered a high temperature of 71.26°F.
The Lower Granite Dam's reservoir registered a high water temperature of 68.29°F.
Water temperatures in the Ice Harbor Dam reservoir have exceeded 68°F for 45 consecutive days, and ranged between 70°F - 72°F for 42 consecutive days. Both the Lower Monumental and Little Goose Dams’ reservoirs have exceeded 68°F for 47 days.

LOWER COLUMBIA RIVER WATER TEMPERATURES: 8/17 - 8/23

Lower Columbia River - 2024 Daily Average and 10-year Average.

Lower Columbia River Water Temperatures: this week, all four reservoirs on the lower Columbia River exceeded 68°F.
The reservoir behind The Dalles Dam had a high average temperature of 71.24°F on August 17 and 18. The reservoir behind John Day Dam reached an average temperature of 71.06°F on August 17.

WEEKLY HIGH TEMPERATURES IN THE LOWER COLUMBIA RIVER: 8/17 - 8/23

On the lower Columbia River, John Day Dam reservoir registered the highest temperature at 72.14°F on August 17. The Dalles Dam reservoir reached the second highest temperature at 71.60°F on August 17 and August 18.
Bonneville Dam reservoir has spent 49 consecutive days above 68°F and both The Dalles Dam and John Day Dam reservoirs registered above 68°F for 48 days.

View previous Hot Water Report issues at wildsalmon.org/HWR

I. EXECUTIVE SUMMARY

For over a month, the lower Columbia and Snake River reservoirs have experienced temperatures above the 68°F “harm” threshold; many of the reservoir waters are between 70°F and 72°F.
Populations of wild Snake River spring/summer Chinook, steelhead, and sockeye all remain listed under the Endangered Species Act and at continued risk of extinction.
As of August 15, only 4 natural-origin Snake River sockeye have successfully migrated past eight dams and their hot reservoirs on the lower Columbia and Snake rivers and returned to their spawning grounds in Stanley Basin in Central Idaho.
The science is clear: in its report published in Sept. 2022, NOAA states that restoring Snake River salmon and steelhead to healthy and abundant levels would require restoration of the Lower Snake River and its migration corridor by breaching the four Lower Snake River dams as part of a comprehensive suite of actions for the Basin.

II. INTRODUCTION

Dave McCoy Salmon Leaping Salmon Leaping © Dave McCoy

The once-abundant anadromous fish populations in the Columbia-Snake River Basin are struggling to survive today primarily due to multiple harms caused by the 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 in the summer months. These cold-water fish begin to suffer harmful effects when water temperatures exceed 68° Fahrenheit.

In Issue 8, Idaho Rivers United reports on the current status of adult wild Snake River Spring/Summer Chinook, steelhead, and sockeye. Despite decades of effort and many billions of dollars in recovery spending, these fish remain on the edge of extinction. Wild fish return as adults today at just 0.1-2% of historic levels - far, far below their historic and recovery levels.

During the summer, SOS’ Hot Water Report provides 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, 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.
Data collection: 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. The water temperatures are taken on the hour. Hourly temperatures are used to find the highest temperatures reached in each reservoir, and hourly temperature measurements are used to find the daily average temperatures.
Average Water Temperature Graphs (below): Daily average temperatures are represented with solid lines, and the 10-year average (2014 - 2023) temperatures are 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 (below): This table outlines the highest water temperatures reported for each reservoir during the week and how many days water temperatures have exceeded 68°F.
Hot water temperature effects to salmon: The longer and the higher water temperatures rise above 68°F, the greater the harm to salmon, 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 WATER TEMPERATURES: 8/8 - 8/16

Lower Snake River - 2024 Daily Average and 10-year Average.

Lower Snake River Water Temperatures: this week, the Ice Harbor Dam's reservoir reached a high average water temperature of 72.01°F on August 10.
The Lower Monumental Dam's reservoir registered a high average temperature of 71.11°F on August 8.
On August 9, the Little Goose reservoir registered 70.89°F, and the Lower Granite reservoir registered a high average of 70.26°F.

WEEKLY HIGH TEMPERATURES IN THE LOWER SNAKE RIVER: 8/8 - 8/16

For over a month, the lower Columbia and Snake river reservoirs have exceeded the 68°F “harm” threshold and many of the reservoirs’ temperatures have ranged between 70°F - 72°F.
The Ice Harbor Dam's reservoir reached the highest water temperature of 72.50°F on August 10.
This week, Lower Monumental Dam’s reservoir registered a high water temperature of 71.37°F and the Little Goose Dam's reservoir registered a high temperature of 71.38°F.
The Lower Granite Dam's reservoir registered a high water temperature of 71.24°F.
Water temperatures in the Ice Harbor Dam reservoir have exceeded 68°F for 38 consecutive days, and ranged between 70°F - 72°F for 35 consecutive days. Both the Lower Monumental Dam’s and Little Goose Dam’s reservoirs have exceeded 68°F for 40 days.

LOWER COLUMBIA RIVER WATER TEMPERATURES: 8/8 - 8/16

Lower Columbia River - 2024 Daily Average and 10-year Average.

Lower Columbia River Water Temperatures: this week, all four reservoirs on the lower Columbia River exceeded 68°F.
The reservoir behind The Dalles Dam had a high average temperature of 71.96°F on August 10 and 11. This week. the reservoir behind Bonneville Dam and John Day Dam both reached an average temperature of 71.60°F.

WEEKLY HIGH TEMPERATURES IN THE LOWER COLUMBIA RIVER: 8/8 - 8/16

On the lower Columbia River, the John Day Dam reservoir registered the highest temperature at 72.50°F on August 8 and August 9. The Dalles Dam reservoir reached the second highest temperature at 72.32°F on August 10 and August 11.
The Bonneville Dam reservoir has spent 42 consecutive days above 68°F and both The Dalles Dam and John Day Dam reservoirs registered above 68°F for 41 days.

V. Current Status of Wild Adult Snake River Salmonids Returns (Numbers as of 8/12/24)

A report by Idaho Rivers United

“Salmon runs have plummeted since the signing of the treaties and reservation executive orders that would protect the Tribes’ harvest rights.[...] wild-origin returns of salmon to the Snake Basin are 0.1-2% of their historical abundance, with many populations at or below a quasi-extinction threshold.” — Historic and Ongoing Impacts of Federal Dams on the Columbia River Basin Tribes, Dept. of Interior

SNAKE RIVER SPRING/SUMMER CHINOOK

SNAKE RIVER STEELHEAD (as of: 8/12/24)

SNAKE RIVER SOCKEYE

Current Status of Wild Snake River Salmonids

Populations of wild Snake River spring/summer Chinook, steelhead, and sockeye all remain listed under the Endangered Species Act, and on a long-term trajectory towards extinction.

NOAA Fisheries’ 2022 report Rebuilding Interior Columbia Basin Salmon and Steelhead outlines the actions necessary to achieve regionally agreed upon mid-range goals for salmonid abundance by 2050. These goals were developed by a diverse group of sovereigns and stakeholders within the Columbia Basin Partnership effort, convened by NOAA’s Marine Fisheries Advisory Committee (MAFAC) in 2017.

The high-range abundance goals reflect “healthy and harvestable” levels of wild salmonids returning to currently accessible habitat in the Snake Basin and are displayed in the compiled data above. The mid-range goals are a halfway point between the low-range, ESA-delisting targets of abundance necessary to ensure long-term survival of the species, and high-range goals.

It is important to note that the high-range goals for Snake River salmonids do not reflect historical abundance, but are based on 1950s spawning escapements. Since then, the still-accessible Snake Basin river habitat of Central Idaho and Eastern Oregon has remained pristine and in places seen improvements in quality and connectivity via restoration activities. As a result, there are thousands of miles of high-quality, cold-water spawning and rearing habitat capable of supporting “healthy and harvestable” salmonid abundances now and into a warmer future.

The premier example of this habitat is the Middle Fork of the Salmon River in central Idaho. It possesses high-quality habitat that supports 100% wild, genetically-diverse salmon runs with unique, locally adapted populations and high resilience to disturbances. If Snake River salmon should be doing well anywhere, it is here. However, every Middle Fork population is non-viable and at high risk of extinction due to low abundance and low productivity. Population graphs of salmon in the Middle Fork mirror those of Snake River salmon in general. This fact underscores that the problem is out of Basin - in the downstream migration corridor.

The Columbia Basin Restoration Initiative (CBRI) document, crafted by the Six Sovereigns, envisions how a comprehensive solution to recovering Columbia Basin salmonid populations will occur. In the case of Snake River salmonids it references NOAA’s findings and says this:

“The NOAA Rebuilding Report concludes that achieving the “highest and only reasonable certainty” of restoring Snake River salmon and steelhead to healthy and abundant levels would require restoration of the Lower Snake River and its migration corridor by breaching the four Lower Snake River dams as part of a comprehensive suite of actions for the Basin. The Rebuilding Report found that breaching is an essential “centerpiece” action for Snake River stocks. Current and projected fish status (as described in the NOAA Rebuilding Report) clarifies that implementation of this centerpiece action is urgent, but implementation can be sequenced appropriately to secure continuity of services provided by the dams if necessary investments are expedited.”

Lower Snake River dam breaching and maximum spill over the remaining four lower Columbia River dams was modeled by the Fish Passage Center (FPC). The FPC found that this would result in 4 times higher smolt-to-adult returns (SARs) and return abundances compared to current population levels.

Sockeye Impacted by Hot Water

Sockeye Neil Ever Osborne Sockeye salmon © Neil Ever Osborne

Hot July and August water temperatures in the lower Snake River reservoirs have created significant problems for Snake River sockeye. It resulted, for example, in approximately 18% of returning adult Snake River sockeye that were detected downstream at the Bonneville Dam failing to return to the Snake and instead straying into the cooler upstream waters of the mainstem Columbia River above McNary Dam. Some level of straying is normal - it’s an adaptive behavior that contributes to salmon’s astonishing resilience and productivity - but a normal year would see stray rates in the range of 2-3%. Unfortunately, despite the slight but encouraging uptick in Snake River sockeye that entered the mouth of the Columbia River this spring/summer, too many aren’t actually returning to the Snake River as they seek cooler waters elsewhere in the Columbia. And few adult sockeye have been detected passing Lower Granite Dam - the last dam on the lower Snake River before crossing the border into Idaho.

These conditions, combined with the fragile status of endangered Snake River sockeye, motivated Idaho Department of Fish and Game (IDFG) to initiate an emergency "Trap and Haul” operation at Lower Granite Dam. Through July, a total of 255 sockeye salmon were trapped at the dam and transported to the Eagle Fish Hatchery. Through genetic stock identification, biologists will determine how many Columbia River sockeye strays are included in that total. This is an important strategy this year to help boost the survival of this critically endangered population, but it is in no way an effective long-term strategy for sustaining, much less restoring it.

As of this writing, just 4 natural-origin sockeye have returned to the Stanley Basin in Central Idaho. Sockeye and other cold water salmonids can handle some hot water—especially in rivers like the Salmon River where cooler tributaries provide refuge during their upriver migration. But the cumulative impact of hot reservoirs in the lower Columbia and the lower Snake must be addressed as quickly as possible to reduce water temperatures and reduce the overall exposure time for these fish to waters above 68°F.

The Hot Water Report is a 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

HWR Banner sockeye salmon with lesions image by Conrad Gowell
Welcome to the Hot Water Report 2024: Warming Waters in the Lower Snake and Columbia Rivers.

I. EXECUTIVE SUMMARY

Salmon and steelhead are migrating in hot water temperatures over the 68°F “harm” threshold. As of August 4, many of the reservoirs have approached over 30 days above 68°F.
On August 5, the Lower Granite Dam reservoir reached the highest water temperature of 72.52°F —more than 4 degrees above the 68°F “harm” threshold, the legal and biological limit identified to protect salmon.
Climate change conditions—deeper droughts, hotter summer peaks, lower flows—all threaten the lower Snake River dams’ reliability, leading to less power when the region needs it.
Diversifying our energy portfolio with wind, solar, and battery storage among other technologies allows us to replace the limited energy production of the lower Snake River dams and ensure we have access to affordable clean energy year-round.
New, clean, and affordable energy sources can—and will—replace the energy provided by the four lower Snake River dams and by replacing the dams, we can provide migrating salmon and steelhead a free-flowing cold river to reach healthy and abundant levels.

II. INTRODUCTION

Monumental I Ice Harbor Rachel Teannalach Monumental I: Ice Harbor 2022, oil on canvas, 48" x 48" © Rachel Teannalach

The once-abundant anadromous fish populations in the Columbia-Snake River Basin are struggling to survive today primarily due to multiple harms caused by the 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 in the summer months. These cold-water fish begin to suffer harmful effects when water temperatures exceed 68° Fahrenheit.

In Issue 7, we will review the most common misconception that the lower Snake River dams are a reliable source of energy production during the summer and winter. However, climate change threatens to make hydropower more volatile, less abundant, and becoming less relevant to the Northwest energy landscape.

During the summer, the Hot Water Report provides 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, 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.
Data collection: 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. The water temperatures are taken on the hour. Hourly temperatures are used to find the highest temperatures reached in each reservoir, and hourly temperature measurements are used to find the daily average temperatures.
Average Water Temperature Graphs (below): Daily average temperatures are represented with solid lines, and the 10-year average (2014 - 2023) temperatures are 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 (below): This table outlines the highest water temperatures reported for each reservoir during the week and how many days water temperatures have exceeded 68°F.
Hot water temperature effects to salmon: The longer and the higher water temperatures rise above 68°F, the greater the harm to salmon, 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 WATER TEMPERATURES: 8/1 - 8/7

Lower Snake River - 2024 Daily Average and 10-year Average.

Lower Snake River Water Temperatures: this week, the Ice Harbor Dam reservoir reached a high average water temperature of 71.52°F on August 5.
The Lower Monumental reservoir registered a high average temperature of 70.46°F and the Little Goose reservoir registered 70.95°F on August 5.
The Lower Granite reservoir registered a high average of 70.39°F on August 6.

WEEKLY HIGH TEMPERATURES IN THE LOWER SNAKE RIVER: 8/1 - 8/7

On the lower Snake River, all four reservoirs continue to register temperatures above the 68°F “harm” threshold. As of August 6, many of the reservoirs have approached 30 days over the 68°F “harm” threshold. The Lower Monumental and Little Goose reservoirs reached 31 days above 68°F. The Ice Harbor Dam reservoir reached 29 consecutive days above 68°F and 26 consecutive days above 70°F.
The Lower Granite Dam reservoir reached the highest water temperature of 72.52°F on August 5. Since August 1, the reservoir behind the Lower Granite Dam has experienced significantly high water temperatures compared to the previous week due to the temporary change of cold water releases from Dworshak Reservoir to conserve water and allow the Army Corps to complete dam power maintenance. This week, hot water temperatures in the lower Granite Dam reservoir reached between 68.09°F - 72.52°F.
This week, the Little Goose Dam reservoir registered a high water temperature of 71.82°F, the Ice Harbor Dam reservoir registered a high water temperature of 71.73°F, and the Lower Monumental Dam reservoir registered a high water temperature of 70.83°F.

LOWER COLUMBIA RIVER WATER TEMPERATURES: 8/1 - 8/7

Lower Columbia River - 2024 Daily Average and 10-year Average.

Lower Columbia River Water Temperatures: this week, all four reservoirs on the lower Columbia River reached water temperatures above 68°F.
The reservoir behind the Bonneville Dam had a high average temperature of 71.78°F on August 3. The reservoir behind The Dalles Dam reached an average temperature of 71.42°F on August 2.

WEEKLY HIGH TEMPERATURES IN THE LOWER COLUMBIA RIVER: 8/1 - 8/7

On the lower Columbia River, the Bonneville Dam reservoir registered the highest water temperature at 72.14°F on August 2. The Dalles Dam reservoir reached the second highest water temperature at 71.96°F on August 2.
The Bonneville Dam reservoir reached 33 consecutive days above 68°F and both The Dalles Dam and John Day Dam reservoirs registered above 68°F for 32 days.

V. Lower Snake River dams’ energy reliability in the face of climate change

On the lower Snake River, we are currently experiencing over 30 days above the 68°F “harm” threshold, with many of the reservoirs reaching water temperatures between 70°F - 72°F. The lower Snake River dams and their reservoirs are creating hot waters that are lethal to salmon and steelhead, leading to a significant decline in their survival. Since the construction of the four lower Snake River dams over 60 years ago, Snake River salmon and steelhead populations have been steadily declining toward extinction. The warming waters, exacerbated by rising temperatures and reductions in snowpack due to climate change, are worsening the conditions for these fish.

Defenders of the status quo often depict the lower Snake River dams as a reliable source of energy production during the summer and winter. However, climate change threatens to make hydropower more volatile, less abundant, and becoming less relevant to the Northwest energy landscape.

How does climate change impact the lower Snake River dams’ energy reliability?

The energy production from the lower Snake River dams (LSRDs) are increasingly variable and annual power production varies unpredictably from year-to-year due to climate change-impacted water conditions and fluctuating seasonal energy generation.

Climate changes affect air temperatures, precipitation, snowpack, and wind patterns in the Pacific Northwest, it brings an increase in land and river heat waves, droughts, and variations in river flow patterns. The increased drought and reduced snowpack constrain the power and capacity functions of the dams.

The dams have a combined “nameplate” capacity of 3443 megawatts, but they do not actually produce remotely that much power. In a year with high water flows, the dams will produce 1136 average megawatts (to give a sense of scale, Seattle City Light supplies customers in the city and some suburbs with 1063 average megawatts). But, in a low water year, the lower Snake dams will generate only 583 average megawatts – about half as much (51.3%) as in a wet year with lots of snow. The median annual generation of the lower Snake dams is just 782 average megawatts.

Then there’s seasonal variability. Water in the rivers does not flow in the same volume throughout the year, so neither does energy production. All over the Northwest and, indeed, the whole West, hydropower production peaks in late spring and early summer, as winter snows melt and rivers rise. Over the ten years from 2014 through 2023, the LSRD produced an output of 1428 average megawatts in May, but just 404 average megawatts in August. Most of the power generation from the LSRDs occurs when the rest of our energy resources are also producing significant output.

The above figures are from the Bonneville Power Administration’s 2024 “White Book”, their annual summary of loads and resources. They are based on records from the previous thirty years of stream flows. But with climate change, the future will not be like the past. In fact, Bonneville has acknowledged that. Until 2022, they based their estimate of hydropower resources on a ninety-year stream flow record. Recognizing that what happened in the 1930s was increasingly irrelevant to today’s conditions, the agency switched to the thirty-year record.

As Bonneville explained, “…over the last several decades increasing temperatures throughout the Columbia River Basin …have contributed to increased average winter and early spring flows, with average peak spring runoff now appearing several days earlier, along with decreased summer flows. The best available climate change science… indicates that in the coming decade, these trends will likely continue. Temperatures in the Columbia River Basin are expected to continue to increase. The region is also expected to experience wetter winters, longer summer dry periods, declining snowpack, higher average fall and winter flows, earlier peak spring runoff, and longer periods of low summer flows.”

But, of course, the next thirty years are not going to be like the previous thirty either. The most recent events are most relevant. Climate change conditions— deeper droughts, hotter summer peaks, lower flows — all threaten the lower Snake River dams’ reliability, leading to less power when the region needs it. The New York Times recently reported, “In the United States, hydropower generation fell 6 percent last year. The decline was mostly attributed to high temperatures having melted snow too quickly in the Northwest, leading to huge water loss that curbed energy production in hydropower plants.”

Diversifying our energy portfolio with wind, solar, and battery storage among other technologies allows us to replace the limited energy production of the lower Snake River dams and ensure we have access to affordable clean energy year-round.

Lower Snake River dams during summer and winter energy demands

In a report, Addressing the Lower Snake River Dams’ Peaking Capacity, the NW Energy Coalition, outlines the limitation of the lower Snake River dams as climate change worsens and its several emblematic consequences the Northwest is heading by keeping the dams in place.

Summer peaking demand in the Northwest often occurs as a heat wave forces residents to turn up air conditioning, most commonly in late summer. Figure 1 shows that late summer has the lowest generation, due to little precipitation and low river flows. Climate change will only exacerbate late summer’s low generation as drought reduces precipitation and river flow. However, late summer is also forecasted to have increasing energy demand in our region, as climate change drives longer and more frequent heat waves across the region. With the effects of climate change, we can expect LSR dam energy generation to become less valuable.

Winter peaking demand in the Northwest most commonly occurs when residents turn up their heating systems. Winter cold snaps in the Northwest are likely to occur in December or January. In Figure 1, the generation profile exceeds the peaking capacity of 132,500 MWh only during February through June, a time period when winter cold snaps are less likely, grid demand is lower in the spring as the winter heating season ends, and there is already an abundance of power on the grid due to spring runoff. December and January are periods of low generation for the LSR dams due to low river flow as precipitation falls as snow. As climate change worsens, this trend may change as more precipitation in winter falls as rain rather than snow. However, climate change also causes more interannual variation, further complicating the ability to forecast future winter sustained peaking capacity.

A pathway to clean reliable energy without the lower Snake River dams

Unprecedented summer heat and deep cold snaps show the urgent need to diversify energy resources to improve reliability during the winter and late-summer demand peaks. As climate change worsens, the dams will only become more unreliable, especially during summer and winter demands, and will remain costly to maintain and operate the four dams.

The Biden-Harris Administration in an historic agreement announced their partnership with Pacific Northwest Tribes and States to restore wild salmon populations, expand Tribally sponsored clean energy production, and provide stability for communities that depend on the Columbia River System. With this step forward from the Administration, it is even more crucial that we mobilize the affordable and clean energy sources we already have at our disposal. Diversifying our energy portfolio with wind, solar, and battery storage among other technologies allows us to not only replace the limited amount of energy produced by the lower Snake River dams, but it also ensures we have access to clean energy when we actually need it – not when we already have a surplus. Prioritizing a diverse portfolio of clean energy sources is the best way to create a sustainable and resilient energy grid as climate conditions become more variable.

New, clean, and affordable energy sources can—and will—replace the energy provided by the four lower Snake River dams. By removing the four dams and restoring a free flowing lower Snake River, we can provide cold, clean, healthy water for salmon and steelhead, recover and protect these once-highly prolific fish populations from extinction, uphold our nation's promises to Tribes, and help feed critically endangered Southern Resident orcas.

VI. In the Media - High Country News: Nez Perce energy transition to save salmon

Just past the [Nez Perce] reservation’s border, a billboard greets the driver with an admonition, urging you to “Honor the Treaty of 1855 with the Nez Perce — Breach the Snake River Dams.”

The billboard is the tribe’s response to the four hydropower dams on the Snake River. The Lower Snake River dams have long been controversial for the part they have played in decimating the Pacific Northwest’s once-abundant salmon and steelhead populations.

As night falls on the reservation, another response can be seen in the growing number of homes illuminated by solar power. In an innovative push to replace the hydroelectricity generated by the four dams, the Nez Perce Tribe is creating a new energy infrastructure that could make it easier to breach the dams and restore the salmon.

SOLAR PANELS SHINE from rooftops across the Nez Perce Reservation thanks to the tribe’s solar initiative, Project 5311. Launched in 2022 under the tribal company Nimiipuu Energy, it is named for the amount of solar power the Snake River dams’ operator says is required to replace the electricity the dams generate: 5,311 megawatts. The tribe’s goal is to eventually produce 5,311 megawatts of energy, beginning by generating 500 megawatts by 2027. It is catalyzing a clean energy transition that could help loosen hydropower’s grip on the Pacific Northwest.

“This is an opportunity to create energy,” said Shannon Wheeler, chairman of the Nez Perce Tribe. “Project 5311 is something of a vision that can be utilized for the development of other energy projects that will definitely come together at some point in time.”

Most recently, on Feb. 23, the Biden administration joined four tribal nations and the states of Oregon and Washington to sign the Columbia River Basin Agreement in support of the development of alternative energy in the Pacific Northwest as part of a path toward breaching all four dams.

“The Biden administration agrees that we need to do something different to recover salmon populations in the Columbia Basin,” said Kayeloni Scott, a member of the Spokane and Nez Perce Tribes and communications consultant for the Nez Perce. “The status quo is not working. It’s not green energy if it’s killing fish.”

Both Scott and Wheeler believe that Project 5311 is on track to meet its goal by 2027. The working mantra for some of the workers and panel installers is that each solar panel represents one fish. In offering solar for salmon, the Nez Perce Tribe hopes to energize a transition that helps the people uphold the deep cultural relationship they have with the fish.

“To see the salmon return would restore peace in my heart,” Wheeler said. “Fishing with my relatives reminds me of times in my life when I was safe and at peace. That is what the salmon covenant means to me.”

Read the full article here

View previous Hot Water Report issues at wildsalmon.org/HWR

I. EXECUTIVE SUMMARY

Snake River salmon and steelhead are struggling today to migrate through lethal water temperatures in the lower Snake and Columbia rivers. On all eight lower river reservoirs, temperatures continue to register above the 68°F “harm” threshold.
On the lower Snake River, the Ice Harbor Dam reservoir registered the highest water temperature of 71.96°F on July 25. This July, the Ice Harbor Dam reservoir has reached 22 consecutive days above 68°F and 19 consecutive days above 70°F. Both Lower Monumental and Little Goose reservoirs have registered 24 days above 68°F.
A free-flowing lower Snake River would significantly cool water temperatures and significantly reduce the slow, effortful migration through 140 miles of hot, stagnant reservoirs and fish ladders.
In the lower Snake River, fish ladders/fish passages are the only way for fish to pass the dams. Fish ladders frequently contain water that is hotter than the average river temperature, and such conditions create or exacerbate migration blockages. By stopping or delaying migration, these blockages reduce salmon survival and reproduction.
A free-flowing river will provide cold-water refuges that salmon and steelhead rely upon during summer migrations, improve their migration travel time, reduce stress and in-reservoir predation, and significantly increase the overall survival of endangered salmon and steelhead.

II. INTRODUCTION

Free Flowing III by Britt Freda Free Flowing III 2023, acrylic and graphite on birch panel 24" x 48" x 1.5" © Britt FredaThe once-abundant anadromous fish populations in the Columbia-Snake River Basin are struggling to survive today primarily due to multiple harms caused by the 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 in the summer months. These cold-water fish begin to suffer harmful effects when water temperatures exceed 68° Fahrenheit.

In Issue 6, we discuss how adult salmon and steelhead must migrate through eight dams and their lethally hot water reservoir and fish ladders. In the lower Snake River, fish ladders are the only route for returning adult salmon to pass the dams. Defenders of the status quo falsely claim the lower Snake River fish ladders allow salmon and steelhead to complete their migration in their historic and natural timing and without additional stress or injury to salmon. Hot water flowing in fish ladders at each dam cause salmon and steelhead to stop or substantially slow their migration, severely reducing their ability to complete their journey and spawn.

During the summer, the Hot Water Report provides 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, 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.
Data collection: 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. The water temperatures are taken on the hour. Hourly temperatures are used to find the highest temperatures reached in each reservoir, and hourly temperature measurements are used to find the daily average temperatures.
Average Water Temperature Graphs (below): Daily average temperatures are represented with solid lines, and the 10-year average (2014 - 2023) temperatures are 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 (below): This table outlines the highest water temperatures reported for each reservoir during the week and how many days water temperatures have exceeded 68°F.
Hot water temperature effects to salmon: The longer and the higher water temperatures rise above 68°F, the greater the harm to salmon, 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 WATER TEMPERATURES: 7/25 - 7/31

Lower Snake River - 2024 Daily Average and 10-year Average.

Lower Snake River Water Temperatures - 2024 Daily Average and 10-year Average. Click on the image to view the graph and click here to view the PDF version with separate graphs for each reservoir.

Lower Snake River Water Temperatures: this week, the Ice Harbor Dam reservoir reached a high average water temperature of 71.67°F on July 25, exceeding its 10-year average of 71°F.
The Lower Monumental reservoir registered a high average temperature of 70.62°F and the Little Goose Dam registered 70.21°F on July 27.
The Lower Granite reservoir registered a high average of 67.19°F. Lower Granite Dam’s reservoir’s average registered below 67°F due to the US Army Corps of Engineers’ continued cold water release effort from the reservoir behind Dworshak Dam. However, these cold water releases do not significantly cool the other three lower Snake River reservoirs.

WEEKLY HIGH TEMPERATURES IN THE LOWER SNAKE RIVER: 7/25 - 7/31

On the lower Snake River, all four reservoirs continue to register temperatures above the 68°F “harm” threshold. This July, the Ice Harbor Dam reservoir reached 22 consecutive days above 68°F and 19 consecutive days above 70°F. The Lower Monumental and Little Goose reservoirs reached 24 days above 68°F.
Ice Harbor Dam reservoir registered the highest water temperature of 71.96°F on July 25. The reservoir behind the Lower Monumental Dam registered the second highest water temperature of 71.26°F on July 27.
The Little Goose Dam reservoir registered a high water temperature of 70.56°F and Lower Granite Dam reservoir reached a high water temperature of 68.52°F on July 26.

LOWER COLUMBIA RIVER WATER TEMPERATURES: 7/25 - 7/31

Lower Columbia River - 2024 Daily Average and 10-year Average.

Lower Columbia River Water Temperatures - 2024 Daily Average and 10-year Average. Click on the image to view the graph and click here to view the PDF version with separate graphs for each reservoir.

Lower Columbia River Water Temperatures: this week, all four reservoirs on the lower Columbia River reached water temperatures above 68°F.
The reservoir behind The Dalles Dam had a high average temperature of 70.88°F on July 27. The reservoir behind the John Day Dam reached an average temperature of 70.70°F on July 25.

WEEKLY HIGH TEMPERATURES IN THE LOWER COLUMBIA RIVER: 7/25 - 7/31

On the lower Columbia River, The Dalles Dam reservoir registered the highest water temperature at 71.24°F on July 27. The John Day Dam reservoir reached the second highest water temperature at 70.88°F on July 25-July 26.
The Bonneville Dam reservoir reached 26 consecutive days above 68°F and both The Dalles Dam and John Day Dam reservoirs registered above 68°F for 25 days.

V. Restoring a free-flowing lower Snake River is vital for protecting its endangered salmon and steelhead from extinction

Each summer, adult salmon and steelhead struggle to migrate from the Pacific Ocean to their spawning grounds in tributaries above the lower Columbia and Snake Rivers. In this process, they encounter eight dams with fish ladders and eight hot water reservoirs. Defenders of the status quo falsely claim the lower Snake River fish ladders allow fish to complete their migration in their historical and natural timing and without additional stress or injury. Despite fish ladders at the lower Snake River dams, returning adult fish often stop or slow their migration as they encounter increasingly hot water in fish ladders and in reservoirs.

What are fish ladders?

Fish ladder armycorps Fish ladder and passage diagram by U.S. Army Corps of Engineers

According to the Army Corps of Engineers, as part of their salmon recovery program, fish ladders and devices to attract fish to the entrances of the ladders help fish pass the dams, “allows adult salmon and steelhead to migrate upstream of a dam on their own, provides fish time to rest as they migrate up the ladder, allows natural migration timing, and ladders are less stressful than other fish passage methods.”

Ohhh…if it were only that simple!

Hot water in fish ladders harms returning adult salmon and steelhead and interrupts their migration.

In the lower Snake River, fish ladders/fish passages are the only route past the dams. Fish ladders frequently contain water that is warmer than the average river temperature, and such conditions can create or exacerbate migration blockages, reducing salmon survival. The ladders can expose adult salmon to especially warm surface waters that are used, causing salmon and steelhead to slow or stop their migration upstream to reach the reservoir. These types of delays can reduce successful migration to spawning grounds, and increase a fish’s total thermal exposure.

Among various salmon and steelhead species, sockeye are especially sensitive to elevated water temperatures. As we reported in Issue 5, many Snake River sockeye have been observed this summer seeking refuge from hot water temperatures in the lower Snake River by moving (straying) into the Mid-Columbia River, where water temperatures are cooler.

Last summer, sockeye salmon counts at the lower Snake River dams declined when water temperatures increased. The Fish Passage Center (FPC) reported sockeye ladder counts and PIT-tag conversion in the lower Snake River dropped precipitously during the first two weeks of July. This drop in fish migrating coincided with a sharp rise in river temperature and an even larger spike in ladder temperatures at Little Goose and Lower Monumental dams. During 2023 high-temperature events, far fewer fish passed the Lower Monumental and Little Goose dams than scientists predicted. In July 2023, the highest temperatures in these fish ladders were between 68°F - 77°F. The FPC also reported that the hot water temperatures in the ladders likely contributed to the additional migration travel time for fish, which resulted in further heat stress accumulation and, therefore, a decline in adult survival and reproduction.

Throughout this month of July, Columbia Basin Research reported lower Snake River fish ladders registered high temperatures between 68°F - 78°F–significantly higher temperatures than the 68°F “harm” threshold, the legal and biological limit identified to protect salmon from lethal water temperatures.

Our options to cool the lower Snake River fish ladders are extremely limited

After the catastrophic 2015 fish kill event, in which at least 96 percent of returning adult Snake River sockeye salmon died in the hot water reservoirs, the Army Corps of Engineers implemented fish cooling systems at Lower Granite and Little Goose dams in an effort to alleviate warming water. They constructed a system to pump this cool water into the Lower Granite Dam fish ladder. It is, however, totally inadequate and does nothing to cool the three downstream Snake reservoirs or meaningfully improve fish passage in those ladders.

When aging ladders and their cooling systems fail, the consequences can be dire, as there are no other options for adult salmon to pass dams and reach their spawning grounds. The water used in ladders are provided either by turbines or pumps, many of which are aging and have failed. In the event of failure, the ladders become inoperable and fish passage ceases. The Fish Passage Center reported that in 2023, fish had an especially difficult time passing the lower Monumental Dam due to high temperatures in the reservoir and fish ladders, made worse by the loss of the ladder’s cool water pump that went out of service.

A report by the Columbia River Inter-Tribal Fish Commission, states that the total cost of ladder repairs and improvements in the lower Columbia and Snake Rivers, identified by tribal, federal, and state technical experts is $160.4M today. Many billions of dollars have been spent to maintain and repair the dam infrastructure on the lower Snake River, yet, wild salmon returning to the Snake River Basin are just 0.1-2% of the abundance at the time the United States entered the 1855 Treaties with Tribes.

Restoring a free-flowing lower Snake River will provide cold clean water for salmon and steelhead and deliver big survival benefits

sockeye salmon in river The lower Snake River dams, their reservoirs, and fish ladders impact fish in many ways, including elevating water temperatures, creating large, stagnant reservoirs, destroying and degrading habitat required for key life stages, and much more.

The science is clear: A free-flowing lower Snake River would no longer force fish to migrate through 140 miles of hot, stagnant reservoirs and fish ladders. A free-flowing river will provide cold-water refuges that salmon and steelhead rely upon during summer migrations, reduce their migration travel time, and significantly increase their survival.

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

Restoring the Lower Snake River

Hot Water Report 2024 - Issue 11.

Hot Water Report 2024 - Issue 10.

Hot Water Report 2024 - Issue 9.

Hot Water Report 2024 - Issue 8.

Hot Water Report 2024 - Issue 7.

Hot Water Report 2024 - Issue 6.

Restoring the Lower Snake River

Hot Water Report 2024 - Issue 11.

Hot Water Report 2024 - Issue 10.

Hot Water Report 2024 - Issue 9.

Hot Water Report 2024 - Issue 8.

Hot Water Report 2024 - Issue 7.

Hot Water Report 2024 - Issue 6.

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