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

• 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

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.

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.

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: 8/24 - 8/29

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 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.

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. 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!

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