Water managers at the U.S. Army
Corps of Engineers, along with federal, tribal, and state fishery biologists, have
determined that water temperature and reservoir inflow are now sufficient to commence
sturgeon flow augmentation operations at Libby Dam, Montana, for endangered
Kootenai River white sturgeon downstream in Idaho.
While this year’s flow augmentation
for sturgeon does not include spilling additional volume over the dam, plans
include increasing flows to full powerhouse capacity for about a week.
augmentation will begin Friday, May 13, at 7 a.m. MDT. Flows will be increased from the current
outflow of 15,500 cubic feet per second to approximately 20,000 cubic feet per
second, and will remain at that level through the weekend. Flows will be increased to full powerhouse
capacity - about 27,000 cubic feet per second Monday at 7 a.m. MDT, and will
remain at that level seven to 10 days before being reduced to 20,000 cubic feet
per second for three days. The remainder
of the dedicated sturgeon volume will be shaped such that there is a gradual
reduction in flows towards the summer flat flow of roughly 7,000 cfs, which
will likely begin in mid-June and remain at that level through August.
sturgeon flow augmentation operation is part of a collaborative, ongoing effort
by regional biologists to enhance spawning and migration conditions for
sturgeon in the Kootenai River near Bonners Ferry, Idaho. Increased flows are intended to provide river
conditions that may increase sturgeon migration to the reach of river upstream
of Bonners Ferry in habitat thought to be conducive to successful spawning, egg
hatching, and survival of larval sturgeon While the Kootenai Tribe of Idaho’s
conservation aquaculture program has steadily increased the number of young
sturgeon in the river since 1992, the Tribe has collaborated with federal and state
partners in recent years to construct instream habitat upstream of Bonners
Ferry intended to provide conditions that may allow adult sturgeon to
successfully reproduce naturally.
sturgeon flow augmentation operation requires a volume of water to be released
from Libby Dam based on the May water supply forecast for Lake Koocanusa. The forecasted inflow volume for the April to
August period is 5.8 million-acre-feet (or 99 percent of average), which sets
this year’s sturgeon volume at 0.93 million-acre-feet.
latest model projections indicate a low chance of exceeding flood stage (1,764
feet above sea level) at Bonners Ferry, Idaho.
Although June precipitation may increase flood risk from downstream
tributaries to the Kootenai River not controlled by the dam, current snowpack
data do not indicate a likelihood that flood stage will be reached or exceeded.
Dam flow and stage projections are based on National Weather Service ensemble
forecasts and are updated frequently during runoff season as weather and
conditions change. Forecast modeling includes
information on elevations, outflow, and Bonners Ferry seasonal elevation and
peak height for the year. To see the
latest projections, visit: http://1.usa.gov/1kP1lSH.
U.S. Army Corps of Engineers' primary consideration in operating Libby Dam is
to minimize risk to human life, health, and safety, while meeting the dam’s
multiple purposes and responsibilities. The Corps will closely monitor Kootenai
River elevation in Bonners Ferry during the sturgeon flow augmentation and will
adjust operations with the aim of staying below 1,764 feet, the local flood
information meeting for Libby Dam operations is scheduled for May 26th at the Boundary
County Extension Office, Bonners Ferry, Idaho, from 6-7 p.m.