YAKIMA — An unsettling discovery by U.S. Geological Survey staff gathering gear in the Yakima Delta on July 12 offered a harsh reminder of the dangers fish face due to this summer’s heat and drought.
Warm water lacking in oxygen killed at least 75 sockeye salmon, according to a report, and photos show some of the dead fish floating on their backs near the shore. Yakama Nation Fisheries Manager Joe Blodgett said it’s likely many more sockeye died while waiting for an opportunity to swim up the Yakima River to spawn, reminiscent of large-scale die-offs caused by similar conditions in 2015 and 2021.
“By the time we got out there, we don’t see anything going on now, but we do know this is definitely something to be concerned about,” Blodgett said. “This year it’s even more frustrating because it’s a record return for adult sockeye in the Columbia Basin.”
USGS fish biologist Toby Kock said water temperatures in the 80s have approached record-highs in the lower Yakima River, creating a thermal barrier for any salmon and steelhead trying to swim in or out of the Yakima Basin. Predation concerns and low flows from the second year of a statewide drought add to the challenge of providing safe passage for fish on their long journey between the ocean and spawning habitat.
Significant work from various groups over recent years established better spawning grounds and more pockets of cold water throughout the basin, and Yakima Basin Fish and Wildlife Board director Alex Conley said the Bureau of Reclamation successfully implemented pulse flows to aid steelhead smolts leaving the basin this spring.
Many more future projects, including the planned removal of the Bateman Island Causeway near the Yakima Delta, should continue to help fight the effects of climate change. However, Blodgett expressed frustration with a lack of short-term solutions to prevent massive death similar to 2015, when an estimated 250,000 sockeye died in the warm waters of the Snake and Columbia Rivers.
Perilous journey
Salmon and steelhead generally won’t swim into the Yakima River basin when the water reaches 70 degrees, and those warmer temperatures also make non-native predators like bass and walleye more active.
The water stayed cool enough early this spring to keep the basin comfortable for outgoing steelhead smolts and the hottest water may subside to allow steelhead and coho to return to spawning habitats in August or September. But adult sockeye face the problem more consistently than other species, since they want to swim upstream in the middle of summer.
It’s one of the biggest challenges facing efforts started by Yakama Nation Fisheries almost 20 years ago to reintroduce a species extirpated from the Yakima Basin in the early 1900s. A recently completed $250 million fish passage facility at Cle Elum Dam allows sockeye to complete outmigration, and the tribe collects fish to bring them up to the spawning grounds when they return.
This year’s massive run of nearly 750,000 sockeye through Bonneville Dam allowed the tribe to transport its full allotment of 10,000 fish and Blodgett said about 100 others reached Prosser Dam thanks to rainstorms and cooler temperatures in June. Any fish that make it to Roza Dam in the Yakima River Canyon are collected and taken up to Cle Elum Lake, but far fewer fish than expected turned into the basin and ultimately reached their destination, where significant work has been done to establish good spawning habitat for sockeye.
“It really hits home for leaders who understand the importance for the Nation culturally and just for the health of the basin,” Blodgett said. “Not only do they provide a chance for some of our First Foods, but they’re bringing nutrients from the ocean and taking them to the upper tributaries of the Yakima River.”
A tagging project led by the Bureau of Reclamation and other monitoring efforts allowed biologists to determine sockeye unable to swim up the Yakima River may go to other spawning grounds or simply stay in the Columbia’s cooler water until it’s safe to swim upstream. Sometimes those fish end up in the dangerously warm delta waters near the mouth of the river, where Kock said the longer they wait, the more they lose energy reserves and endanger their lives.
Mid-Columbia Fisheries Yakima Basin program director Becca Wassell said early season heat has led to an increase in steelhead smolts dying on their way out of the basin, since their window for leaving keeps getting smaller. But the full effects of the ongoing drought and heat won’t be known for steelhead for another three to four years, when the outgoing trout are scheduled to return from the ocean to spawn.
Restoring habitat
After years of projects focused on restoring habitat and establishing better fish passage along the upper Yakima River and its tributaries, Blodgett said focus appears to be shifting to addressing problems in the lower river.
With the help of the Yakima Basin Integrated Plan, the Yakama Nation secured several grants Blodgett said should answer some of the questions surrounding the lack of fish traveling through that part of the river. He credited the Benton Conservation District for taking the lead on a project looking at habitat problems caused by invasive stargrass, and Kock said the district’s working to establish more cold water refuges for migrating fish.
Wassell said Mid-Columbia Fisheries worked with conservation districts to plant 11,980 riparian trees and shrubs along the Yakima River and its tributaries in 2023 to create more shade to keep the water cool. Still, she acknowledged that shade won’t be effective for another 10 years as the trees grow.
