By ZACH URNESS/Salem Statesman Journal
Tens of thousands of kokanee salmon have died between Green Peter and Foster reservoirs due to a new extreme water drawdown at the reservoirs intended to help native fish.
Over the weekend, masses of dead kokanee were spotted in the Sunnyside Park area of Hughes Creek at Foster Reservoir outside Sweet Home. It alarmed anglers and kayakers.
“I saw hundreds if not thousands of dead fish floating down the river toward Foster Dam yesterday,” Shelli Hopper-Moore of Springfield told the Statesman Journal on Monday.
Kokanee are a landlocked species of sockeye salmon that have become a popular game fish and are stocked in reservoirs across the Willamette Basin.
In this case, the fish died of “barotrauma and gas bubbles in their bloodstream and body cavity,” said Beth Quillian, spokeswoman for the Oregon Department of Fish and Wildlife.
The fish did not die of toxins in the water or infection, officials stressed.
The deaths occurred because the fish were sucked from very deep in Green Peter Reservoir, through a regulating outlet in the dam to essentially the surface of the water downstream, U.S. Army Corps of Engineers biologist Greg Taylor said.
The rapid move from deep to shallow water caused the fish’s swim bladders to rapidly inflate.
“Their swim bladders were so inflated that they couldn’t go down,” Taylor said. “That was why people saw so many of them floating on the surface.”
Four reservoirs — including Green Peter — are being dropped to historically low levels in an effort to improve the passage of wild juvenile spring chinook from upstream habitat, through the dams and into the ocean.
The drawdown was part of an injunction ordered by U.S. District Judge Marco Hernandez following a lawsuit by the Native Fish Society, Wildearth Guardians and Northwest Environmental Defense Center.
The lower reservoir levels are aimed at helping baby salmon pass through outlets deep on the dams they’d otherwise struggle to locate. It’s part of a multi-billion dollar plan to rebuild wild salmon runs and shift how the 13 dams in the Willamette Basin operate.
This autumn is the first time Green Peter has been dropped to such low depths. It’s currently at an elevation of 883 feet above sea level, and will drop even lower, until the reservoir is almost transformed back into a river. It’s the lowest the reservoir will have been since it was built.
The problem is that kokanee, which inhabit the reservoir and are swimming deep to stay cool this time of year, are getting pulled through the dam outlets and thrust into shallow water downstream of the dam. That has caused the die-off, officials said.
Taylor said there was every reason to believe kokanee would continue to be killed in this way, but that the Corps are legally bound to continue.
Mark Sherwood, executive director of the Native Fish Society, said the Corps needed to look at ways to release the water more slowly, so as to have less impact on the kokanee.
“That said, as special and cool as the kokanee fishery is, these fish are stocked, they’re not native and they’re not imperiled,” Sherwood said. “The fish we’re looking to help — spring chinook — are native and are deeply imperiled. It’s absolutely critical we find a way to get those juvenile fish to from new habitat and back to the ocean.”
The Corps is considering making the drawdowns permanent, amid a process that will determine how the Willamette Valley Project of dams operates in the future.
Taylor noted that to save endangered spring chinook, it might mean a trade-off of losing some kokanee, which are stocked in large amounts in multiple locations.
Joe Moritz, president of the angling group Kokanee Power of Oregon, said some good could come of the situation.
“It is very sad to see so many dead kokanee for any reason,” he said. “However, to be as positive as possible in light of a likely grim situation, this may eliminate the issue of overpopulation that this lake has been suffering from. In a perfect situation, there will be fewer, but larger kokanee in the lake into the future. We will likely not know for sure for the next 1 to 3 years.”
If this process is killing the kokanee, why wouldn’t it kill the chinook fry as well?
The answer, according to Taylor, is that the chinook fry tend to swim in the upper water column of the reservoir. That’s actually why they have such a struggle finding outlets in the dam at normal reservoir levels and a primary reason the levels are being dropped.
The Corps is trying to get the fry to within around 25 feet of the outlets so they can feel the current and follow it down and out the dam. But the key is that they’re doing so from the upper water column and swimming down. The kokanee, by contrast, are swimming in the deepest part of the reservoir and being pulled out from the bottom.
Government always messing things up. Someone should be fired.