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

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.⁸ With 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

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