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NW Fishletter #394, June 3, 2019

[9] Washington Drought Worries Fish Managers More Than Power Generators

A quickly diminishing snowpack combined with a forecast for warmer- and drier-than-average conditions in parts of Washington this summer prompted Gov. Jay Inslee to add 24 watersheds to the three basins already under an emergency drought declaration since April 4.

Fish managers say the poor snowpack in parts of the Columbia Basin is bad news for late-migrating fall Chinook juveniles and a myriad of summer and fall adult salmon and steelhead that struggle in warmer water when low flows persist.

But when it comes to power generation, Bonneville Power Administration officials note that Washington's drought conditions are at least partly offset by the wetter conditions in Montana and Idaho. Water supply throughout the Federal Columbia River Power System is 91 percent of normal, BPA spokesman David Wilson said.

That's still below average, but not nearly as poor as the water supply in parts of Washington, including the mid- and upper Columbia River basin.

The culprit is snowpack, which dropped from about 80 percent of normal on April 1, to 52 percent on May 20, prompting Inslee's declaration. Snowpack in several areas is well below 50 percent. In the central Columbia River basin, it's 25 percent of normal, and in the upper Yakima River basin, it's at 20 percent. The upper Columbia was showing 55 percent of its normal snowpack while the lower Yakima River basin had 53 percent. The data measures the snow water equivalent--or the amount of water in the snowpack--compared with the 30-year average from 1981 through 2010.

NOAA's Climate Prediction Center also updated its El Nino Advisory, increasing the chances that warmer temperatures will persist in the Northern Hemisphere through the summer to 70 percent, and the chance that it will continue through fall to between 55 and 60 percent. Although spring predictions tend to be less accurate, the majority of models still predict El Nino to continue through 2019, the update says. The update reflects a 5 percent increase in chances for El Nino to continue through summer, and through the fall.

The Washington Legislature appropriated $2 million for drought response, and funding for agencies seeking relief will be available in June. The funds can be used for actions to relieve hardships, and could include drilling water wells, moving the location of water withdrawals, leasing water and conserving water.

Washington last declared a drought emergency in 2015. That summer, an estimated 250,000 adult sockeye perished in the Snake and Columbia rivers. There were also extensive sturgeon and steelhead deaths, said Bill Tweit, Columbia River fishery coordinator for the Washington Department of Fish and Wildlife.

Tweit said drought is a "cascading problem" for fish. It starts with less water in the rivers and streams. That means hot summer temperatures will heat the water more quickly. And, since the snowpack melts early, it also means cooler water won't be coming into the system throughout the summer.

It's not the drought itself, but the increase in river temperatures that has us nervous--and its possible effects on upstream migration," Tweit said.

Idaho's B-run steelhead may be the most at risk, he said. Fish managers are already limiting and closing fishing, and will institute a series of rolling closures to follow the steelhead as they migrate upstream this summer and fall. "In recreational fisheries, we're not anticipating we'll need to do more, other than what we've already done--which is pretty darned extensive," he said.

The agency will also closely monitor river temperatures, look for opportunities to find cold water refuges for fish, and coordinate efforts with other agencies. "We'll be expecting the agencies to do what they can, but also recognizing you can only do what you can," he said.

While snowpack throughout the Columbia Basin is below average, BPA isn't exactly in drought mode.

"We are fortunate because the Columbia Basin is so large a lower snowpack in one area of the region can be offset by wetter or better snowpack conditions elsewhere," BPA spokesman David Wilson said in an email. "For example, even though it has been unusually warm and dry across northern and eastern Washington and southwest British Columbia, it has been a very wet spring in Idaho and Montana, and considerable snowpack remains in the Canadian Rockies where temperatures have been cooler," he wrote.

Figures from NOAA's Northwest River Forecast Center show total precipitation for drainages in the Snake River basin for this water year since Oct. 1 ranged from 91 to 107 percent of normal. In contrast, the middle Columbia's upper tributaries saw only 65 percent of its normal precipitation, and the Columbia River basin above Grand Coulee received only 73 percent of normal rain or snow.

According to a Forecast Center map, the water supply forecast for the North Fork Clearwater River at Dworshak Dam is currently 110 percent of normal, and for the Snake River at Lower Granite Dam, it's 127 percent of normal.

There have also been system improvements that could help fish through this summer's drought.

In the Snake River, Little Goose and Lower Granite dams now have water cooling systems to prompt adult fish to continue their journey through the ladders. The ladders can act as a "thermal barrier" when water temperatures at the top of the ladder are warmer than those at the base of the ladder.

Gina Baltrusch, spokeswoman for the U.S. Army Corps of Engineers in Walla Walla, said that in 2015, the Corps rented pumps to bring cooler water from deep inside the forebays into the ladders. In 2016 and 2017, the agency completed modifications which now supplement water at the entrance to the fish ladders, and pump cooler water from deep in the forebay to spray at the top of the ladder. She said water releases from Dworshak Dam are also used to help cool water in the Snake River.

While the 2015 sockeye mortalities are often cited, a Corps news release on the water cooling improvements notes the vast majority of the fish were headed for the upper Columbia River, and most of those bound for the Snake River actually died in the lower Columbia River, before reaching the Snake. -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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