Green Peter drawdown delayed

Scott Swanson

The U.S. Army Corps of Engineers announced last week that, due to unspecified equipment complications, the planned drawdown of Green Peter Reservoir will be delayed, likely until next fall.

That development comes after the Corps released a plan earlier this month, produced by an “expert panel” of scientists and others, that will require Green Peter to be drawn down to 780 feet above sea level, some 220 feet below full pool.

The planned deep drawdown at Green Peter would not only stop hydro power production, but it would also impact recreation, as water levels will drop far below the Thistle Creek and Whitcomb Creek boat ramps on the lake.

Initially, the target date for the draw-down was Nov. 15, and the result would be that the dam’s power plant would be unable to produce electricity. Not only does that electricity produce auxiliary power for the surrounding area, but it powers the dam’s own operations. A back-up generator will be required to operate the dam during the drawdown and that’s the rub, said USACE spokesman Tom Conning.

“We won’t be able to draw Green Peter down this year because we won’t have that back-up generator in place,” Conning said, noting that when the report was released that wasn’t clear. “The generator we need for backup power will not be installed this year. I don’t know whether it’s supply or placement or whatever. Because that can’t be installed, we won’t be doing that particular drawdown this season.”

The draw-down plan is the result of the expert panel’s response to a September 2021 court order by U.S. District Judge Marco Hernandez that the USACE make changes at its dams in the Willamette Basin so that juvenile salmon and steelhead could pass through them more easily. Its stated goal is “to establish a self-sustaining population of spring Chinook salmon upstream of Green Peter Dam.”

Hernandez ruled that the Corps must change its dam operations in numerous ways to improve fish migration and water quality in four tributaries of the Willamette River, including the South Fork of the Santiam River, on which Foster Dam is located.

“Deep drawdowns” require the Corps to lower the elevation of the reservoirs to within 25 feet or less of the dams’ regulating outlets, prioritizing water flow over the top of the dam rather than through hydropower turbines, especially during the night when fish have higher rates of migration.

The fish are listed under the Endangered Species Act and, according to environmentalists who have sued the Corps on multiple occasions over the last decade to gain information about dam operations and the health of fish populations, dams on the Willamette River have blocked access to spawning grounds, which has contributed to population declines.

Hernandez’s injunction is in response to a lawsuit filed in early 2021 by Northwest Environmental Defense Center, Wildearth Guardians and Native Fish Society, arguing that the Corps should be more transparent about its dam operations and their impacts on salmon and steelhead smolts heading out to sea.

Conning said the need for a generator is the biggest obstacle that the Corps must overcome before the drawdown can occur.

“ I think we anticipate it to happen next fall, because we will have a little more time,” he said.