|
|
|
Kootenai River will be rising as Libby Dam
increases river flows for sturgeon spawning |
|
May 13, 2016 |
by A. Scott Lawrence
Public Affairs Specialist
U.S. Army Corps of Engineers
You will be seeing the Kootenai River rising and
filling its banks over the next several days.
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.
Sturgeon flow augmentation began on Friday, May
13, in the early morning hours. Flows were
increased from what had been an 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 next be increased to full powerhouse
capacity, about 27,000 cubic feet per second, on
Monday at 7:00 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.
The 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. 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.
The 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.
The latest model projections indicate a low
chance of exceeding flood stage (1,764 feet
above sea level) at Bonners Ferry. 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.
Libby 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.
The 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 stage.
A public information meeting for Libby Dam
operations is scheduled for May 26th at the
Boundary County Extension Office, Bonners Ferry,
Idaho, from 6:00-7:00 p.m. |
|
|
|
Questions or comments about this
article?
Click here to e-mail! |
|
|
|
|
