Low water hampers sturgeon spill test

Last month’s efforts to boost white sturgeon spawning on the Kootenai River were not as successful as hoped, mainly because of this year’s low-water conditions, a U.S. Fish and Wildlife Service official said Thursday.

For seven days in early June, water was released over Libby Dam’s spillway with the goal of enticing adult sturgeon to move into optimal spawning habitat just upstream from Bonners Ferry, Idaho.

“It made some difference ... but we didn’t get the river stages that we have seen in past years without spill,” said Jason Flory, the wildlife agency’s Kootenai sturgeon recovery team leader. “It’s not surprising we didn’t get a big change in sturgeon behavior in the river. That’s unfortunate, but that’s the way it goes. We worked with what we had.”

Flory said the river reached a maximum elevation of 1,761 feet at Bonners Ferry, a flow level that has been exceeded in past years without spilling water over the dam.

Pete Rust, a biologist with Idaho Fish and Game, said a total of seven adult sturgeon tagged with sonic transmitters  — five females and two males — made it into the “Braided Reach” upstream from Bonners Ferry in June.

That stretch has a cobble-and-gravel riverbed where spawning is expected  to be more successful than the sediment-covered riverbed downstream.

Rust said four fish were in the Braided Reach before the spill test commenced.

He said it appears two sturgeon may have been influenced by the increased flows after the test started. An average of about 7,000 cubic feet of water per second was released over the spillway, in addition to running the dam’s turbines at a powerhouse capacity of 25,000 cfs.

Rust said that all seven sturgeon returned downstream of Bonners Ferry by June 30.

“Overall, the test and the planning and execution of it went pretty well for the first year,” Flory said. “The management among the various agencies went very well.”

Flory said spill operations are expected to be carried over the next two years to determine if there are any benefits for white sturgeon, a species that is listed as endangered largely because biologists believe spawning success has been minimal to nonexistent since Libby Dam was built in the early 1970s.

Reporter Jim Mann may be reached at 758-4407 or by e-mail at jmann@dailyinterlake.com.