Libby Dam Outflow Update
Sturgeon Flow Releases to Begin
by U.S. Army Corps of Engineers
June 10, 2009
Outflow from Libby Dam will increase from the current rate of 13,500 cfs to 23,500 cfs on Wednesday evening, June 10 over a 2-hour period from 6:00 pm to 8:00 pm. Outflow will further increase to full powerhouse capacity (approximately 27,000 cfs) at 6:00 am on Thursday morning, June 11.
This increase marks the commencement of sturgeon flow augmentation operations for 2009. Flows will remain at full powerhouse for 7 days, and ramp down to 20,000 cfs for 5 days, 17,000 cfs for 5 days, and 15,000 for 5 days following 2006 BiOp ramping rates for flow reduction. Following the sturgeon operation, flows will be reduced to the summer steady flow of 6-9,000 cfs.
For more information, contact Greg Hoffman, Fishery Biologist, U.S. Army Corps of Engineers.
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The following Columbia Basin Bulletin, Issue No. 487, dated June 5, 2009, provides some background information about sturgeon spawning and Libby Dam flow releases.
Libby Dam Releases Set To Begin To Encourage Increased White Sturgeon Spawning www.cbbulletin.com
Montana's Libby Dam soon will start releasing water 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 as early next week. 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."
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.
But within a week, the dam will ramp up to full powerhouse flows of 26,000 cfs for seven days, then to 20,000 cfs for seven days, then 15,000 for five days. At the end of the month, flows will drop to stable summer releases of between 6,000 and 9,000 cfs.
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