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NW Fishletter #392, April 1, 2019

[10] Low Flows From Cold, Dry Weather Causing Columbia Basin Fish Problems

This year's extremely cold February followed by a cold and extremely dry March have combined to create some unusual situations for fish managers in the Columbia Basin--including trapped sturgeon, extended chum operations, and emergency water releases to save hatchery fish.

With only a quarter to a third of the normal precipitation in much of the basin in March, the Columbia River Technical Management Team (TMT) expressed continuing concerns at its March 20 meeting about low river flows throughout the region.

"We've been below average, and we're continuing to go below average," TMT Chair Doug Baus reported for the U.S. Army Corps of Engineers. He noted the April-to-September water supply forecast at The Dalles is down to 83 percent of average, and April-to-July at Lower Granite Dam is 88 percent.

The low snowpack in the upper Columbia, along with the unseasonably cold weather, caused concerns for salmon managers and hydropower producers. Significantly colder-than-average temperatures kept the snowpack solid into March. The cold weather, low flows for hydropower production and high natural gas prices prompted the Bonneville Power Administration to ask customers on March 1 to reduce energy use when possible to relieve stress on the power system.

But warming temperatures brought a bit of good news for TMT members, who had been meeting weekly to decide whether to keep releasing water from Grand Coulee Dam to ensure that chum salmon nests--or redds--below Bonneville Dam have a minimum tailwater elevation of 11.3 feet. In addition, the water protects redds of about 14,000 fall Chinook that spawned below Bonneville Dam this year. The chum are threatened under the Endangered Species Act, while the Chinook are not listed.

Team members learned at their March 6 meeting that there's virtually no chance of making their April 10 target elevation of 1,283.3 feet behind Grand Coulee Dam, and that continuing to release water for chum would only draft the reservoir even farther below target.

On March 11, the Corps' Aaron Marshall reported that, in his analysis, Lake Roosevelt would drop an extra 10 feet by April 10 if the TMT decides to operate to a flow objective of 130,000 cubic feet per second for chum at Bonneville Dam, instead of dropping releases to meet the 65,000 cfs requirement to keep water flowing to fall Chinook redds at Vernita Bar below Priest Rapids Dam.

With a choice between taking an action that would almost certainly wipe out the emerging chum below Bonneville or drawing down a reservoir that may impact the survival of other juvenile salmon later this spring, the TMT opted to continue operations for chum and hope that a forecast of warmer weather would begin to melt snow and add to the river flows.

Finally, the Bureau of Reclamation reported there was enough melting snow in the Snake River by March 20 to augment the Columbia at Bonneville Dam so that extra releases from Grand Coulee Dam were not needed. Grand Coulee's reservoir elevation dropped from 1,269 feet on March 1 to 1,258.6 feet on March 20. Baus offered some hope for TMT members--a forecast of rain, just in time for spring break, he said.

The lower water levels mean the Corps will be operating at the minimum generation needed to maintain grid reliability, with the rest going to spill once spring requirements for juvenile fish passage begin, Baus noted. Total dissolved gas levels have increased, and are ranging between 109 and 114 percent in Bonneville's tailwater because of the low flows, which could impact the redds.

Low river flows from the lack of precipitation and late low-elevation snowmelt has been a problem throughout the Columbia Basin.

On March 4, the Corps came to the rescue at the Kootenai Tribe of Idaho Hatchery, where all of its burbot eggs could have been lost after the Kootenai River froze and surface water intake pumps could not bring cold water into the facility. Shawn Young, of the Kootenai Tribe, told the TMT on March 6 that temperatures were dropping below zero at night, and there wasn't enough depth in the water to create the pressure needed to pull water into the facility. The Corps increased outflows at Libby Dam from 4 kcfs to 10 kcfs to keep the pumps submerged, enabling the hatchery to continue operating.

Young said burbot eggs are extremely sensitive to temperature changes, and without river water, it's too difficult to maintain water that's cold enough for their needs. Without the extra water from Libby Dam, the facility would have had to release the eggs into the river.

At its March 13 meeting, TMT member Sue Ireland, who represents the Kootenai Tribe, thanked the Corps and the Bonneville Power Administration for supporting the emergency action and reported that operations at Libby Dam would return to normal by March 15.

Low flows also created a problem for the Oregon Department of Fish and Wildlife, which was called to Sturgeon Lake on March 16. The lake is fed by the Columbia River, and low water levels in the river had trapped an estimated 200 to 400 sturgeon in a pool in the lake during low tide, said Fish and Wildlife spokesman Rick Swart.

"Our folks have been attempting to move water into that pool as an interim measure to keep the fish wet, and to oxygenate the water," he told NW Fishletter.

Swart said his agency asked the Corps if they could get water released from Columbia River dams, but learned that most of the nearby dams are not used for storage.

"They would have had to start releasing water clear up [at Grand Coulee Dam], and who knows when that would raise the level of Sturgeon Lake," he said.

Additional snowmelt and the ocean tides came to their rescue. By Tuesday, fish biologists reported seeing only 20 to 30 sturgeon still in the pool. "The presumption is, a good chunk of them were able to escape" during high tide, he said.

Swart noted that the sturgeon had been creating a deeper area in the pool with their swimming movements to dig into the mud. "That's just another one of those miraculous stories of how wildlife adapts to Mother Nature. But with that said, we were not going to sit around and count on that adaptability."

He said although nearby residents had never before seen sturgeon trapped in the lake by low water, "those fish have been there for 300 million years, and probably dealt with it a time or two." -K.C. Mehaffey

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NW Fishletter is produced by NewsData LLC.
Publisher/Editor-in-Chief: Mark Ohrenschall, Editor: K.C. Mehaffey
Phone: (206) 285-4848 Fax: (206) 281-8035

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