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Sturgeon flow augmentation set to begin Monday |
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May 11, 2017 |
Water managers at the U.S. Army Corps of
Engineers, along with federal, tribal, and state
fishery biologists, have determined that spring
run-off conditions warrant the commencement of
required flow augmentation at Libby Dam for
endangered Kootenai River white sturgeon
downstream in Idaho.
The flow augmentation operation will increase
Libby Dam discharge to full powerhouse capacity
for about a week, on two separate occasions, in
an effort to provide river conditions that may
increase sturgeon spawning success in the lower
Kootenai River in Idaho.
Sturgeon flow augmentation will begin Monday,
May 15, as local Kootenai River tributaries
downstream of Libby Dam are forecasted to peak.
Discharge from Libby Dam will be increased to
full powerhouse capacity, approximately 23,200
cubic feet per second (cfs), and will remain at
that level for about one week before decreasing
to 18,000 cfs.
A second week-long pulse of powerhouse capacity
flows is expected to start at the end of May to
coincide with peak high elevation inflows
upstream of Lake Koocanusa.
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, federal, state, and tribal
partners have collaborated in recent years to
construct instream habitat upstream of Bonners
Ferry intended to provide conditions that will
allow adult sturgeon to successfully reproduce
on their own.
The sturgeon operation requires a volume of
water to be released from Libby Dam based on the
May water supply forecast for Lake Koocanusa.
The May water supply forecast for the April to
August inflow volume is 8.2 million-acre-feet,
or 140 percent of average; which sets this
year's sturgeon volume at 1.20
million-acre-feet.
While snowpack has begun to melt in western
Montana and northern Idaho, cooler temperatures
and early precipitation in May have maintained
the snowpack in the upper Kootenai Basin above
Libby Dam.
The latest projections indicate a moderate
chance of exceeding flood stage at Bonner Ferry,
Idaho, which is 1,764 feet. However, June
precipitation may increase Kootenai River flood
risk due to runoff from tributaries downstream
of Libby Dam. The dam's 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 meetings for Libby Dam
operations is scheduled for Thursday, May 18, at
the Kootenai River Inn, Bonners Ferry, Idaho,
from 7 to 9 p.m. |
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