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Libby Dam releases designed to help sturgeon

by Western News
| June 9, 2009 12:00 AM

Libby Dam plans to increase water releases this week in an effort to improve spawning conditions for the Kootenai River’s endangered white sturgeon.

“We’re on the cusp of starting the sturgeon release,” said Brian Marotz, a Montana Fish, Wildlife and Parks fisheries biologist who is on a multi-agency white sturgeon recovery team. “It may be as soon … we’re watching the position of the adults. As soon as they are in position and as soon as the water temperature is in the range where we can use the (dam’s) selective withdrawal, we will start the release.”

The U.S. Army Corps of Engineers announced the outflows would increase over a two-hour period on Wednesday evening from the current rate of 13,500 cubic feet per second to 23,500 cfs. Outflow will then further increase to full powerhouse capacity – which is approximately 27,500 cfs – at 6 a.m. on Thursday.

Flows on the river will be high through most of June as part of an effort to get sturgeon to migrate upstream from Bonners Ferry, Idaho, into suitable spawning habitat in a cobble- and gravel-bottomed stretch of river called the braided reach.

For years, sturgeon did not travel that far upriver, unsuccessfully spawning in sediments.

Last year, with increased June flows, a radio-tagged fish traveled the farthest distance upriver that has been recorded in years.

“We’re trying to mimic the temperatures we had last year, because last year the fish went further upriver and stayed there longer than have in a long time,” Marotz said.

Flow will remain at full powerhouse for seven days, then ramp down to 20,000 cfs for five days, 17,000 cfs for five days and 15,000 cfs for five days. Following the sturgeon operation, flows will then be reduced to the summer steady flow of 6,000 cfs to 9,000 cfs.