Low river flows, an unprecedented heat wave and a lingering drought have combined to create deadly conditions for fish in Northwest rivers.

After 2015, when an estimated 250,000 adult sockeye died in the lower Columbia River, much of the focus has been on this year's return of endangered Snake River sockeye.

Two weeks after a severe and persistent heat wave, Columbia Basin fish managers are in a hopeful wait-and-see mode about the Snake River sockeye run. But the impacts are not just to sockeye in the Snake River. Agencies across the West are starting to report impacts to anadromous fish runs in rivers throughout the region.

Hatcheries are holding back releases of juvenile salmon or trucking them to the ocean. States are asking anglers to report dead fish and avoid fishing in the heat of the day in order to prevent additional stress. The Idaho Department of Fish and Game has suspended bag limits and other rules at an 8-acre pond because it will be nearly dry by the end of July.

Although temperatures west of the Cascade Range have dropped, many parts of eastern Washington, Oregon, Idaho and Montana continue to experience unseasonably warm weather.

Washington Gov. Jay Inslee declared a drought emergency on July 14 for most of the state that includes all counties, but excludes Seattle, Tacoma and Everett.

"A heat dome in late June brought triple-digit temperatures and smashed all-time records across the state, rapidly worsening drought conditions," the Washington State Department of Ecology said in a news release.

The dry conditions since the beginning of March reduced water supply forecasts throughout the region, Ryan Lucas, forecaster at NOAA's Northwest River Forecast Center, told the Northwest Power and Conservation Council on July 14. He said the only basins with normal or above-normal forecasts are in the Clark Fork Basin and snow-fed portions of the Washington Cascades.

Temperatures across the Northwest soared in June to more than 6 F above normal, according to the NWRFC.

From Oct. 1 through July 12, most of the Columbia Basin experienced 50 to 90 percent of normal seasonal precipitation.

Meanwhile, the outlook for river levels continues to decline. As of July 13, the NWRFC projects Columbia River's flow through September at 89 percent of normal at Grand Coulee Dam and 83 percent at The Dalles Dam.

The heat wave that hit the Northwest in June pushed up river temperatures in the basin, putting protected fish at risk. The U.S. Army Corps of Engineers started releasing cold water at Lower Granite Dam on the Snake River on June 22, two to three weeks earlier than usual, Aaron Marshall with the Corps' Northwestern Division told the Council.

Due to the early water release, the Dworshak Reservoir could only be filled to about 3 feet below full, Marshall said.

The heat wave has stressed fish across the region based on anecdotal reports across the Northwest, said Patty O'Toole, the Council's Fish and Wildlife Division director, during the July 14 meeting.

Fish managers on the Yakima and Deschutes rivers reportedly have had to move fish to colder water upriver, she said.

"That is just a smattering of what we've heard," O'Toole said.

Also on July 14, Columbia Basin fish managers reported some good news—and some not-too-good news—about returns of this year's endangered Snake River sockeye at the Columbia River Technical Management Team meeting.

Claire McGrath, representing NOAA Fisheries on TMT, said the sockeye that have crossed eight federal dams and been trapped above Lower Granite Dam are showing definite signs of heat stress, appearing dull in color. However, compared to 2015, the Snake River sockeye are making it to the uppermost dam faster, and more of them have made the journey compared to the 10-year average, she said.

As of July 14, a total of 358 sockeye were counted passing Lower Granite Dam, according to the Fish Passage Center.

McGrath said fewer than usual sockeye trapped at Lower Granite Dam had wounds from sea lions, seals or fishing nets, but more than half of them were suffering from lesions that appeared to be Pacific lamprey bites. However, the wounds could also be some kind of bacterial fungus, and the agency has asked for a pathology analysis.

Jonathan Ebel, TMT representative for the Idaho Department of Fish and Game, said 40 additional sockeye were trapped and hauled to the Eagle Fish Hatchery near Boise to add to the 38 that were previously trapped and taken to the hatchery for broodstock. He said the agency's health lab on the same campus will run some bacterial cultures, but an initial assessment indicates the wounds were caused externally.

Tom Lorz, who represents the Confederated Tribes of the Umatilla Indian Reservation, said it's "highly suspect" that the lesions are from Pacific lamprey.

Dave Swank, representing the U.S. Fish and Wildlife Service on TMT, agreed, saying it's "really, really rare" to have lamprey latch onto fish in freshwater. "Maybe there's something going on in the ocean, but lamprey counts are well under the 10-year average, so I guess it leaves me scratching my head a little bit."

TMT members reported that similar marks seen on summer Chinook in the Snake River, and on sockeye in the upper Columbia River.

A few weeks ago, warm water in the Klamath River led to an outbreak of a deadly pathogen that likely killed large numbers of juvenile Chinook salmon, the Yurok Tribe reported (CU No. 2006 [10.1]). And Northern California is seeing other impacts from the heat.

The California Department of Fish and Wildlife says juveniles from this year's endangered winter Chinook in the Sacramento River could be wiped out. In the Klamath River, the agency moved 1.1 million juvenile fall Chinook from the Iron Gate Fish Hatchery to prevent losses from warm water temperatures. "Due to warm water temperatures, low water flow and an exceedingly high probability of succumbing to disease in the river, CDFW decided to retain these salmon within its hatchery system over the summer until Klamath River conditions improve," the agency's news release says. Juveniles were not released from the hatchery for the first time since it was built in 1962, the agency said. The young fish were relocated to another hatchery facility.

In the Columbia River's John Day Pool, anglers have reported three dead sturgeon, Laura Heironimus, sturgeon, smelt and lamprey unit lead for the Washington Department of Fish and Wildlife, told Clearing Up. She said that's not an unusually high number, but the agency is keeping a close eye on the sturgeon population after 2015, when several dozen large, adult sturgeon died in lower Columbia River reservoirs, likely caused by low flows and warm water temperatures.

Last year, she said, WDFW extended its cool water sanctuary—where anglers are not allowed to fish—so fewer sturgeon are being handled this summer. "That's already having a benefit," she said.

Heironimus is also concerned about this year's run of Pacific lamprey, as the temperature impacts on the species are under-studied.

WDFW is asking anglers to report unusual numbers of dead fish or sea creatures, or even single losses of large sturgeon to help track this year's impacts.

"It's unfortunate when we have to investigate any potential die-off, but with the public's help we can get a more comprehensive picture of certain environmental impacts on these populations," Kirt Hughes, manager of WDFW's Fish Management Division, said in a news release.

Meanwhile, the Idaho Department of Fish and Game is encouraging anglers with a fishing license to take as many fish as they want from South Butte Pond near Clayton.

The agency issued a salvage order on July 15 because low water levels, diminished flows into the pond and elevated water temperatures are creating unsuitable conditions for trout. "The pond will likely be nearly dry by the end of July," the agency's news release says.

Fish managers throughout the region will continue to monitor conditions and take actions where possible for the rest of the summer, which is also predicted to be drier and hotter than normal.

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K.C. Mehaffey covers fish issues for Clearing Up, and is editor of the NW Fishletter. She joined the NewsData writing team in February 2018. From lawsuits to scientific studies, she is enjoying the deep dive into the Columbia Basin's many fish topics.

Contributing Editor

Dan has covered stories from Seattle to Tbilisi; spent time with the AP, Everett Daily Herald and Christian Science Monitor; and was twice a member of a team nominated for a Pulitzer Prize. He and his wife have three young children and live in Seattle.