Scott Swanson
How high will the water be in the local lakes this summer?
That’s a question that county parks officials are pondering as they watch water that normally would be stored in Green Peter Reservoir at this time of year flowing over the dam spillway.
It’s planned, the U.S. Army Corps of Engineers said, and it’s the result of a lawsuit filed a little over a year ago by environmentalists who argued that the Corps should be more transparent about its dam operations and their impacts on salmon and steelhead smolts heading out to sea.
“Basically, we’re releasing water from the spillways, which is different than normal,” said Tom Conning, a public affairs specialist based in the Portland District, which oversees Foster and Green Peter dams as part of the Willamette Valley Project.
“Normally, we release water – slightly less – through turbines to generate power. During this operation, we’ll release a bit more water and won’t be generating power until May 1 or for 30 days, whichever is longer.”
Green Peter’s water level is currently being maintained at slightly over 980 feet above sea level, which is how the Corps measures lake levels. Full pool is 1,010. In a good water year – last year was not – the lake is usually at 1,000 feet or more by Memorial Day.
Typically, according to the Corps, Green Peter’s surface ele-vation is below the spillway crest from mid-October through early March, which prevents juvenile fish from leaving the lake. Then operators begin filling the lake to store water for dry-season use.
County Parks Director Brian Carroll expressed concern about the change’s impacts, but his department is taking a “wait-and-see” approach to the changes, which stem from a court injunction that resulted from a lawsuit filed by the Willamette Riverkeeper environmental organization in December 2020.
U.S. District Judge Marco Hernandez last September ordered the U.S. Army Corps of Engineers to make changes at its dams in the Willamette Basin so that juvenile salmon and steelhead could pass through them more easily.
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 requires the Corps to 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.
The injunction required a deep drawdown of Cougar Reservoir on the South Fork of the McKenzie River and spill operations at Foster Dam last fall.
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.
Studies have shown that both salmon and steelhead juveniles tend to exit the lake during nighttime hours, over the spillway rather than through the turbines.
Hernandez wrote that the actions were necessary because, “(a)s evinced by the listed species’ continuing decline, the Corps’ failure to provide adequate fish passage and mitigate water quality issues is causing substantial, irreparable harm to the salmonids.”
Conning said the Corps completed an “implementation plan” on Nov. 29.
“There’s been lot of working through details,” he said.
Other measures are aimed at improving water temperatures and levels of dissolved gas below the dams.
Also, Conning said, “we will use this to study downstream migration over the spillways, to inform future operations.”
Since last fall, when the Corp implemented its response to the injunction, Corps officials have been working to determine when juvenile fish leave the lakes, how they exit, what routes they take, passage rates and survival rates.
An “expert panel,” comprised of two members designated by the plaintiffs, two National Marine Fisheries Service biologists, two Corps employees, and two “ad hoc” federal representatives, has been created to determine the restrictions with which the Corps must comply.
Panel members are tasked with coming up with dates, hours, and amount of turbine use for Foster spill operations “that will provide the most benefit to the listed salmonids as a whole” and recommend whether spring refill should be delayed.
That biological opinion is expected later this year.
Conning said the spill at Green Peter reached the correct level on March 18 and at that point water was released over the dam, rather than through the hydroelectric plant.
In a report detailing its plans, the Corps said it will “conduct/prioritize spillway operations at Foster Dam during the spring for juvenile fish passage, beginning in the spring of 2022.”
Hydropower production should not be affected during the operations, the Corps said in its plans, which are viewable at http://www.nwp.usace.army.mil/Locations/Willamette-Valley/Injunction.
Conning said recreational use of the lakes should continue as normal at Foster and Green Peter.
“We don’t anticipate this specific operation impacting recreation. We would be releasing water either way. Normally, we would be releasing water to generate power. This is very visual, comparatively.
This spring, Foster Reservoir is being held at minimum conservation pool (elevation 613 feet) and water is being released from the dam’s spillway, with limited turbine operation through May 15. Beginning May 16, Foster Reservoir will be refilled, aiming for full pool by Memorial Day Weekend. Beginning June 16 through mid- to late-July, the Foster fish weir will be operated to maintain good downstream water temperature management.
Carroll, whose department operates multiple camping facilities and two boat ramps each at the two lakes, said decreasing water levels will likely impact Green Peter’s recreation use before Foster’s.
“Basically, I think I’m less concerned, at this point, about Foster,” he said. “They’ve been saying they will do everything they can to fill it by Memorial Day Weekend. But I’m not sure what that looks like.”
If the lake is filled quickly, debris – floating logs and other items – will have less opportunity to move to the shore, he said.
“People will have to be mindful that we may have more debris than usual.”
Also, if Foster is lowered earlier than usual after Labor Day Weekend, that could impact recreation, which generally continues through the first few weeks of September if the weather cooperates.
“The normal operation of the lake has them drawing it down in October,” Carroll said.
He said his biggest concern is Green Peter.
Although the area is getting plenty of rain currently, a lot of that water is flowing over the dam.
“Normally, at this time of year, they’d be storing water,” Carroll said. “I’ve been told for many years by the folks who control the dams that Green Peter is not a snow-driven system; it’s a rain-driven system. Instead of holding at 1,010 feet, they’re holding at 980, passing water. If late May and June are dry, we’re probably not going to see Green Peter fill. That’s my concern, whether we will ever see Green Peter fill again.”
He acknowledged that the answer will come with the conclusions of the Corps panel tasked with determining what works best for fish populations.
“The Corps is trying to figure this out as well,” he said. “They need a certain amount of storage so they can keep the river flowing.
“This is a difficult place to be in because they have the spring (fish) run to take care of, but they also have the fall run. If you’re passing water in the spring, what do you do in the fall?”
As far as recreation is concerned, boaters can use Whitcomb Creek Boat Ramp, on the northeast side of the lake, until the water level drops to 972 feet – “and it’s getting tight at 974,” Carroll said. Thistle Creek, located farther to the west, is accessible to 922 feet, he said.
“The reality is the weather,” he said. “If things go the way we like, and weather patterns are normal during the year, I think we’re going to be OK.”
If not, “if we don’t get normal rainfall, Whitcomb Creek could be out of the water by the Fourth of July.”
This isn’t just a current issue, he noted. The county has extensive plans to develop more camping facilities on Green Peter.
“We have a lot of plans to invest in projects up there,” Carroll said. “But we certainly have to take a practical approach with taxpayer funds. We have to be careful not to spend too soon.”
Green Peter and Foster are certainly not the only lakes impacted. The Corps’ Willamette Valley Project operates 13 dams in the Willamette River basin, which provide flood risk management, power generation, water quality improvement, irrigation, fish and wildlife habitat and recreation. All are under the injunction, some more severely impacted than even Foster and Green Peter, Carroll noted.
“People are going to be looking to get into the water,” he said. “We will be doing the best we can to facilitate that access.”