Moving spring chinook past drawdowns to cost $7 million
Crews at Wanapum and Rock Island dams are scrambling to complete modifications that will allow the fish ladders to operate under low-water conditions expected to last well into summer.
The Wenatchee World
WENATCHEE — The thousands of spring chinook already headed up the Columbia River have no idea the amount of work they’ve mobilized at Rock Island and Wanapum dams.
Giant cranes are hoisting and positioning. Divers are installing. Engineers and biologists are assessing and calculating. Accountants are crunching.
Nearly every department at both the Chelan and Grant County PUDs is focused on getting the fish past the dams and onto their upriver spawning streams.
The 65-foot crack discovered Feb. 27 across part of Wanapum Dam’s concrete spillway has forced a historic 26-foot drawdown of its reservoir to take pressure off the dam.
Crews at both dams are scrambling to complete more than $7 million in collective modifications that would allow the fish ladders to operate under low-water conditions that are likely to persist well into summer.
The drawdown has left the upstream exits of Wanapum Dam’s adult fish ladders high and dry — unusable for the migrating fish.
A Grant PUD contract crew from Max J. Kuney Construction of Spokane was busy Tuesday hanging in a steel basket along the dam’s upriver face installing submersible pumps, wiring and pipes that will get water flowing again through the dam’s two adult fish ladders.
When work is complete the exit of each ladder will be fitted with a giant steel tank that will catch the fish as they emerge from the ladder.
The tanks will each be fitted with a water slide to ease the fish into the river, some nine to 13 feet below.
“I consider it a minor miracle that we’re going to make April 15, but we’re going to,” Ray Ellis, Grant PUD’s hydro supervisor, said Tuesday, of the deadline both PUDs have committed to meeting.
Fish tend to follow the deepest part of the river, Russ Langshaw, fisheries scientist for the utility, said Tuesday. That means that some 80 percent of the 1,200 to 1,500 spring chinook that will soon be passing the dam per day prefer to use ladder on the Grant County side.
Those numbers will climb to a peak of about 25,000 migratory fish per day during the summer run, he said.
Until they see that the fish are adjusting well to the ladder changes, PUD officials plan to trap as many as 1,500 fish per day as they arrive at Priest Rapids Dam, downriver, and haul them by truck to release points above Wanapum or, possibly, above Rock Island Dam, Langshaw said.
At the Chelan PUD’s Rock Island Dam, some 36 miles upriver, a different modification is needed.
The lowered Wanapum reservoir means the Rock Island tailwater — the water on the dam’s downriver side — is too low under the lowest water conditions for the fish to enter the dam’s left, right and center fish ladders.
The ladder on the Chelan County side is the one favored by some 75 percent of the fish, Keith Truscott, the Chelan PUD’s director of natural resources, said Thursday. That’s the one they’re working on now.
Crews and divers from Knight Construction of Deer Park were at work Thursday.
The 84-foot extension consists of two, 30-foot steel ladder sections with baffles inside that create the turbulent white-water effect that attracts fish. A large steel tank, called a “resting pool,” sits at mid-extension. A smaller resting pool is at the top of the extension at the entrance to the dam’s existing ladder.
Under current water conditions, all of Rock Island’s ladders are usable without the extensions, Truscott said. But as summer wears on and riverflow subsides, the ladder entrances would likely be above water in August or September without the extensions in place.
Utility officials don’t want to take any chances.
“This fish coming up are a way of life for the Pacific Northwest,” Keith Truscott, director of natural resources for the Chelan PUD, said Thursday. “A lot of effort has been put into recovering and increasing the fish runs to the Upper Columbia. We shouldn’t allow an unplanned incident like this to deter us from our goal to be good stewards of the environment.”
The Chelan PUD will pay some $4.3 million to extend the ladders on the dam’s Chelan and Douglas County shorelines. Grant PUD’s cost to modify its ladders is estimated at $3 million.
All modifications will have to be removed when the cracked spillway is fixed and the reservoir level is raised to normal, officials from both utilities say.
Both dams will handle passage of juvenile salmon — young fish headed to the ocean to mature — using their existing systems.
Wanapum has a giant waterslide for juvenile fish that will operate at a lower flow, but one still strong enough to attract fish. Rock Island will pass juveniles using its “notched” spillgates.
Experts from state, federal and tribal agencies have approved the PUDs’ emergency plans for fish.
“We’re only down 3.5 to 4 feet, so we have much more normal operations than you see on the Wanapum pool,” Truscott said. “We’ve got confidence in the plan we’ve put together and our confidence has been bolstered because we’ve already seen fish coming up the ladders.”