Libby Dam season update

The U.S. Army Corps of Engineers held an informational meeting about the Libby dam Wednesday, covering sturgeon habitat restoration progress, predicting a low precipitation season and showing fish growth.

Greg Hoffman, a fisheries biologist with the USACE, said sturgeon are starting to migrate upstream of Bonners Ferry.

“Low and behold, we actually caught a fertilized sturgeon egg upstream” he said. “A lot of us were jumping up and down.” Efforts to improve the sturgeon’s habitat have been going on for about a decade.

Hoffman is a part of the Flow Plan Implementation Protocol Technical Team, a working group supporting habitat restoration for the sturgeon.

Due to habitat recovery work, the Kootenai River now has more deep pools of water between Bonners Ferry and Moyie Springs, he said. Sturgeon needs depth to continue to migrate.

“It’s all about habitat,” he said. The team is shaping flow and temperature for the fish.

“I feel, before I retire, we are going to have [sturgeon] fish spawn naturally in the Kootenai river and survive,” he said.

Hoffman also noted, even though there will be low water all this year, it is going to be steady through September.

Sonja Michelsen, a USACE water management worker, said precipitation in the Kootenai River Basin has been below average this year. There has been less snow than normal and it has been a dryer year.

The sturgeon pulse, an extra flow of water given to the fish during their spawning and migration period, will be about a third less water volume this year at 800,000 acre feet, due to the lack of water, she said. There will still be a pulse, but smaller than it was previously.

Jim Dunnigan, a researcher with Montana Fish, Wildlife & Parks, shared data on various fish growth in the Kootenai River. Dunnigan found that the growth rate of fish decreased as they get bigger while the younger ones had higher growth rates.

“What really kind of surprised us was how steep this was — for these larger fish” he said.

Higher water discharge from September to November correlated with more and better fish growth, he said. Also, the higher the summer pool of water, the better smaller fish performed.

Almost 1,200 individual fish have been marked and recaptured to create population, weight and size estimates, he said.