Sockeye salmon with lesions dying from hot water in the Columbia-Snake River Basin ©Conrad Gowell

I. INTRODUCTION

Welcome to the 2023 Hot Water Report: Warming Waters in the Lower Snake and Columbia Rivers.

During the summer, this weekly report provides an update on real-time water temperatures in the lower Snake and Columbia River reservoirs via graphs and analyses, a summary of the highest weekly water temperatures at the forebay/reservoir of each federal dam, and a monthly status of adult returns for different salmon and steelhead populations as they make their way back to their natal spawning grounds. We’ll report first-hand from scientists, Tribal members, fishing guides, advocates, and other experts about the challenges facing these rivers – and our opportunities to improve and restore them - in order to recover healthy, resilient fish populations and the benefits they deliver to Northwest communities, other fish and wildlife populations (including the critically endangered Southern Resident orca), and ecosystems.

Many once-abundant anadromous fish populations—fish that hatch in freshwater, go to sea, and return to freshwater to spawn—in the Columbia-Snake River Basin are on the brink of extinction today due primarily to harms caused by federal dams and their warming reservoirs. The Columbia-Snake federal hydro-system harms and kills both juvenile and adult fish in multiple ways, including by elevating water temperatures in the summer months in their large, stagnant reservoirs. These cold-water fish begin to suffer harmful effects when water temperatures exceed 68° Fahrenheit.

This week, on the lower Snake River, the reservoir behind the Ice Harbor Dam registered the highest water temperature at 70.65°F on September 1. Issue 10 is focused on the Nez Perce Tribe’s Department of Fisheries Resources Management’s 2023 Snake River Basin Anadromous Fish Status Report Card that outlines (i) the historical returns for Snake River fish, (ii) forecasted 2023 returns for Spring/summer Chinook salmon and steelhead, (iii) Quasi-Extinction Threshold for Spring/summer Chinook salmon and steelhead (QET; critical threshold signaling fish are nearing extinction), and (iv) urgency to restore Snake River fish.

Without immediate and meaningful conservation actions, Snake River salmon and steelhead populations will continue to decline toward extinction. Restoring a free-flowing Snake River by removing its four dams and replacing their services is essential to provide cold, clean, healthy water for salmon and steelhead, 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.

View the past Hot Water Report issues here: Hot Water Reports - Compiled

The Hot Water Report is a joint project of the Save Our wild Salmon Coalition, American Rivers, Association of Northwest Steelheaders, Columbia Riverkeeper, Earthjustice, Endangered Species Coalition, Environment Oregon, Idaho Conservation League, Idaho Rivers United, Natural Resources Defense Council, National Wildlife Federation, Northwest Sportfishing Industry Association, Orca Network, Sierra Club, Snake River Waterkeeper, Wild Orca and Wild Steelhead Coalition.

II. READING THE DATA - Water Temperatures in the Lower Snake and Columbia Rivers

Figure 1. Lower Snake River Water Temperatures - 2023 Daily Average and 10-year Average. Click on the image to view the graph.

Introduction to the data:
The daily average temperature at the four reservoir forebays (measured with sensors stationed at various depths below the reservoir surface, immediately upstream from the dam) in the lower Snake River (above) and the lower Columbia River (below) for 2023 is represented with solid lines and the 10-year average (2013 - 2023) temperatures with dashed lines of the same color. The dotted line across the graph represents the 68°F “harm threshold” for adult and juvenile fish.

The longer and the higher these temperatures rise above 68°F, the greater the harm, including: migration disruption, increased metabolism, increased susceptibility to disease, reduced reproductive potential (by reducing egg viability), suffocation (warm water carries less dissolved oxygen), and in the worst case - death.

The four reservoirs on the lower Snake River are large, stagnant pools that absorb enormous amounts of solar radiation that cause the water to warm. These waters inundate and destroy diverse micro-habitats that healthy rivers support, including cold-water refuges that salmon and steelhead rely upon during their migration. Without these vital pockets of cold water, salmonids cannot rest and recover on their journeys—adults moving upstream to spawn and juveniles moving downstream to the ocean. Rising temperatures and reductions in snowpack in recent decades due to climate change create warmer waters, which results in lower survival and reduced reproductive success for salmon and steelhead.

Figure 2. Lower Columbia River Water Temperatures - 2023 Daily Average and 10-year Average. Click on the image to view the graph.

Discussion of data:
Since April, temperatures in the lower Snake River and the lower Columbia River reservoirs have steadily increased. Figure 1 shows, the reservoir behind the Ice Harbor Dam had the highest average temperature of 70.41°F on September 1. The Lower Monumental reservoir had the second highest average temperature of 69.08°F on September 1.

Figure 2 shows the reservoir behind the Bonneville Dam registered the highest average temperature of 70.52°F on September 1. Both juvenile and adult salmon continue to experience water temperatures above the 68°F “harm” threshold.

Below, we present the weekly high water temperatures for each reservoir on the lower Snake and Columbia rivers for September 1 - September 6.

A note on the data: The 2023 lower Snake River and lower Columbia River water temperature data presented in the Hot Water Report are collected from the Columbia River DART program by Columbia Basin Research, University of Washington, using data courtesy of the U.S. Army Corps of Engineers (USACE) and USGS. The 10-year average water temperature data is courtesy of the Fish Passage Center. There is no data available for the Lower Monumental 10-year average water temperature, and McNary reservoir hourly water temperature data is collected from USACE with current available data. Little Goose Dam's daily average and hourly data are unavailable for September 6. Graphs and tables were assembled by SOS Staff.

III. WEEKLY HIGH WATER TEMPERATURES: September 1 - September 6

This week, on the lower Snake River, the reservoir behind the Ice Harbor Dam registered the highest water temperature at 70.65°F on September 1, and the Lower Monumental Dam registered the second highest temperature at 69.40°F on September 1.

This week, on the lower Columbia River, the Bonneville reservoir registered the highest water temperature at 70.52°F on September 1 and 2.

IV. Nez Perce Tribe’s 2023 Snake River Basin Anadromous Fish Status Report Card

Since time immemorial, the Nez Perce Tribe, also recognized as the Nimiipuu, have been connected to the lands and waters of modern-day Idaho, Washington, Oregon, and Montana - long before the creation of the Nez Perce Reservation in the mid-1800s.¹ As a sovereign nation within the United States, the Nez Perce Tribe retains the “inherent right to fish at usual and accustomed fishing stations, and hunt, gather, and graze livestock on open and unclaimed lands, all outside of the reservation boundary.”¹ However, due to forces such as settler encroachment and dam construction, the number of traditional fishing sites for the Nez Perce Tribe and the overall fish populations have declined precipitously.² The Nez Perce Tribe’s Department of Fisheries Resources Management is a critical program that works to protect and enhance fishing rights reserved by the Tribe in its treaties with the United States.³ Notably, the Department of Fisheries Resources Management have significantly rebuilt Snake River Fall Chinook returns, re-established Snake River coho salmon - extirpated in the 1980s from the Snake River Basin - and has become one of the largest and most successful tribal fisheries programs in the United States.³ 

In May 2021, the Department of Fisheries Resources Management released an analysis called “Snake Basin Chinook and Steelhead Quasi-Extinction Threshold Alarm and Call to Action.” That analysis indicated that nearly half of the wild spring Chinook populations in the Snake River Basin have crossed a critical threshold known as the Quasi-Extinction Threshold (QET), signaling they are nearing extinction, and without immediate intervention, many may not persist in the coming years. In addition, the basin’s steelhead populations also face alarming threats to their continued existence.

To understand what Quasi-Extinction Threshold (QET) means, the department outlined a key definition:

• QET means 50 or fewer natural-origin spawners on the spawning grounds for 4 consecutive years.
• QET also signifies that adult salmon abundance in a population nearing absolute extinction, and the probability of recovery is low without substantial intervention.

“Quasi-Extinction means, aside from biological terminology, you are running out of options. When you have fewer than 50 fish on spawning grounds, the genetic diversity is really limited. Your ability to pull these fish out of inbreeding depression and other stochastic-type risks is really limited. Any type of environmental hazard can cause havoc when you have fish populations that are so low. We are certainly running out of management options.” —Dave Johnson, Department Manager of the Nez Perce Tribe’s Department of Fisheries Resources Management

The Snake and Columbia River Basin contains some of the very best available habitat for salmon populations to recover to any significant level of abundance. However, with predictions pushing the populations below 50 spawners, the four lower Snake River dams are a major factor preventing salmon from reaching spawning grounds and reproducing in viable numbers.

Without immediate and meaningful conservation actions, Snake River salmon and steelhead populations will continue to decline toward extinction. Projected returns of adult spring/summer Chinook salmon in 2023 are estimated to be about half the 2022 return. Returns of adult steelhead in 2023 are similar to the 2022 return. Both are far below the goals for healthy, harvestable and abundant salmon and steelhead.

Below is the Nez Perce Tribe’s Department of Fisheries Resources Management’s 2023 Snake River Basin Anadromous Fish Status Report Card that includes historical returns for Snake River fish, forecasted 2023 returns for Spring/summer Chinook salmon and steelhead, QET, and urgency to restore Snake River fish.

2023 Snake River Basin Anadromous Fish Status Report Card

Figure 1. Snake Basin salmon and steelhead stock specific population status summary; over half the historical populations are extinct and none of the existing populations are considered healthy and harvestable.

Historical Context:
The abundance, diversity, and distribution of Snake Basin salmon and other anadromous fish (steelhead, lamprey, sturgeon) are just a sliver of their historical condition:

• Less than half of the 117 historical populations remain (Figure 1).
• Abundance of wild fish in the remaining populations is 1-2% of the 2+ million historical abundance (Figure 2).
• The Columbia Basin Partnership (CBP) Phase 2 Report A Vision for Salmon and Steelhead: Goals to Restore Thriving Salmon and Steelhead to the Columbia River Basin | NOAA Fisheries establishes contemporary management goals.

Figure 2. Snake Basin salmon and steelhead current abundance (black dots) relative to historical abundance and Columbia Basin Partnership (CBP) goals; Columbia Basin Partnership high-range goals 5 – 31% of historical. All but one stock below low-range goals. Fall Chinook salmon above low-range, but below mid-range goals.

Recent Status: Spring/summer Chinook salmon and steelhead are on the brink of extinction.

1) Wild Spring/summer Chinook salmon

Figure 3.1. Assessment of Snake Basin wild spring/summer Chinook salmon abundance relative to Quasi-Extinction Threshold (QET) of 50 or fewer spawners. Actual abundance updated through 2022 returns and future abundance modeled through 2027. Red font and data points indicate populations and years with abundance below QET threshold. 

• Wild spring/summer Chinook salmon returns from 2018 through 2021 to the Snake Basin averaged 6,050 fish with 42% of the Endangered Species Act (ESA)-listed populations being at or below the Quasi-Extinction Threshold of 50 fish for four consecutive years (Figure 3.1).  

Figure 4. Annual (abundance of adult wild spring/summer Chinook salmon passing into the Snake Basin relative to critical (quasi-extinction index), ESA-delisting index, Columbia Basin Collaborative healthy and harvestable (high range) thresholds. Data provided by Idaho Department of Fish Game (Baum et al 2022 and T. Copeland personal communication).

• Wild spring/summer Chinook salmon returns in 2022 were slightly higher at 16,048 fish but are still well below the Index for ESA-delisting (43,000) and far from the healthy and harvestable goal (235,000).
• Forecasted natural-origin spring/summer Chinook salmon return for 2023 is ~7,500 adults (Figure 4).
• The QET assessment was updated to reflect the 2022 returns. Generally, adult returns in 2022 were slightly higher and reduced the number of populations at or below the QET criteria of 50 natural-origin spawners.

“The increase in Snake River basin natural-origin spring/summer returns in 2022 is welcomed and consistent with our expectations for improved survival under good ocean conditions and high spill hydro-operations. However, it is important to understand that while the 2022 return is an improvement over recent years, abundance remains precariously low and well below criteria for ESA-delisting - let alone our goals representing healthy and harvestable status.” —Jay Hesse, Director of Biological Services of the Nez Perce Tribe’s Department of Fisheries Resources Management

2) Wild Steelhead

Figure 3.2. Assessment of Snake Basin wild steelhead abundance relative to Quasi-Extinction Threshold (QET) of 50 or fewer spawners. Actual abundance updated through 2022 returns and future abundance modeled through 2027. Red font and data points indicate populations and years with abundance below QET threshold.

• Wild steelhead returns from 2018 through 2021 to the Snake River Basin averaged 12,297 fish with 19% of the ESA listed populations being at or below the Quasi-Extinction Threshold of 50 fish for four consecutive years (Figure 3.2).
• Wild steelhead returns in 2022 were 9,807 fish well below the Index for ESA-delisting (30,800) and healthy and harvestable goal (147,300).
• Forecasted natural-origin steelhead return for 2023 is ~9,500; with less than 1,000 B-run natural-origin predicted.

Future Trend:
If adult abundance continues to decline at a similar rate as the last 10-years, over 60% of the spring/summer Chinook salmon populations and 44% of the steelhead populations may drop below 50 natural origin spawners by 2027 and some populations (e.g. Tucannon spring Chinook salmon) will likely become extinct (Figure 3.1 and 3.2).

Urgency:
To achieve the Columbia Basin Partnership’s Snake Basin spring/summer Chinook salmon mid-range goal (137,000 natural origin fish at Lower Granite Dam) by 2050, abundance from each generation to the next must increase by at least 44% for the next 27 years (seven generations) (Figure 5).

Figure 5. Observed generational growth rate of Snake Basin spring/summer Chinook salmon versus targeted minimum generational growth rate necessary to achieve mid-ranged goals (137,000) by 2050. Red bars indicate generations that had fewer progeny returning than their parents (generational decline). Yellow bars (none in this time series) indicate generations with more progeny returning than their parents (generational increase, but at level insufficient to reach 137,000 by 2050). Blue bars indicate generations with more progeny than their parents (generational increase, at level sufficient to meet or exceed 137,000 by 2050. Black bar reflects current in-season projection for 2023.

Transformative Actions:

An analysis of the actions necessary to achieve healthy and abundant salmon and steelhead, recently completed by the National Oceanic and Atmospheric Administration (NOAA) Fisheries Rebuilding Interior Columbia Basin Salmon and Steelhead and the Statement of the American Fisheries Society (AFS) and the Western Division AFS (WDAFS) About the Need to Breach the Four Dams on the Lower Snake River, reports that breaching the four lower Snake River dams is necessary and essential, along with a comprehensive suite of other actions.

"Breaching the dams improves survival [by speeding] the passage down to the ocean so fish travel in a river, not in a series of reservoirs. The fish evolutionarily are developed to make it down to the ocean in a certain amount of time. Well, we've extended that period of time to a month so they run out of reserves, they run out of their food by the time they reach the ocean. The only way these fish are going to have a chance is if they can get back to the mountains. Otherwise, we lose them. We're losing them every year, and we need to turn that around. We need to be able to breach the dams to have those fish get to where they're supposed to be.” —Dave Johnson, Department Manager of the Nez Perce Tribe’s Department of Fisheries Resources Management

Data used by the Nez Perce Tribe’s Department of Fisheries Resources Management:
Adult salmon and steelhead returns are monitored at lower Snake River dams and in tributary (population) habitats.

• Real-time (in-season) and annual fish ladder window counts of combined wild and hatchery-origin fish can be found at Fish Passage Center’s website (https://www.fpc.org/currentdaily/HistFishTwo_7day-ytd_Adults.htm) https://www.fpc.org/currentdaily/HistFishTwo_7day-ytd_Adults.htm and the Columbia Basin Research website (https://www.cbr.washington.edu/dart/query/adult_daily).
• Separate estimates of wild-origin abundance and hatchery-origin abundance are generated post-season for fish passing Lower Granite Dam and available on the StreamNet website:
  • Natural Chinook - https://www.streamnet.org/data/trends/trend/?trendid=46108;
  • Hatchery Chinook - https://www.streamnet.org/data/trends/trend/?trendid=46109;
  • Natural Steelhead - https://www.streamnet.org/data/trends/trend/?trendid=46110;
  • Hatchery Steelhead - https://www.streamnet.org/data/trends/trend/?trendid=46111.
  • Spring/summer Chinook and steelhead estimates are described in Idaho Department of Fish and Game Technical reports (Baum et al 2022; https://collaboration.idfg.idaho.gov/FisheriesTechnicalReports/Res22-11Baum2020Wild%20Adult%20Steelhead%20Chinook%20Salmon%20Abundance.pdf and fall Chinook salmon are provided on the Nez Perce Tribe website (http://kus.nptfisheries.org/kus-data).
• Population specific estimates of wild-origin, hatchery-origin, and total spawner abundance are available on the StreamNet website (https://www.streamnet.org/home/data-maps/fish-hlis/).

References:
1. Nez Perce Tribe History: Traditional Ways and Treaties
2. Honoring Nations, Nez Perce Tribe Fisheries
3. Nez Perce Tribe: Fisheries Resources Management: DFRM-Management-Plan-2013-2028.pdf (nezperce.org)