from Libby Dam will spike next week to benefit wild Kootenai River white
sturgeon, but this year river operators will increase flows twice – once to
encourage the sturgeon to move upriver into spawning grounds and a second time
to trigger further movement upstream and spawning.
double spike this year comes courtesy of a much higher than normal snowpack and
winter precipitation and an April to August water supply forecast of 8.19
million acre feet, which is 139 percent of normal, according to Jason Flory of
the U.S. Fish and Wildlife Service.
a Tier 5 year for sturgeon operations, he said, which means that at least 1.2
MAF can be discharged from Libby Dam, which is near the towns of Libby, Montana
and Bonners Ferry, Idaho. The operation is defined in the Service’s 2006
biological opinion for Libby operations, covering both sturgeon and bull trout.
introduced the sturgeon operation in a System Operations Request FWS #1 to the
interagency Technical Management Team for their approval at TMT’s meeting this
week Wednesday, May 10 (http://www.nwd-wc.usace.army.mil/tmt/agendas/2017/0510_2017_USFWS_Libby_sturgeon_SOR_2.pdf).
the goal is to provide conditions that will enable sturgeon to migrate to, and
spawn over, rocky substrates that exist upstream of Bonners Ferry,” the SOR
says. “This two-peak approach was successfully implemented in 2013 and 2014.
Telemetry data for spawning Kootenai sturgeon females from those years indicate
that a higher proportion migrated just upstream of Bonners Ferry than in recent
Dam’s sturgeon operations are the first releases of the year for fisheries
benefits at federal hydro projects. Elevated releases are carried out the
remainder of the summer and early fall to benefit salmon and steelhead runs.
first peak, which begins Monday, May 15, will coincide with low elevation snow
melt, Flory said, and the second peak will be triggered when the higher
elevation snow begins to melt.
first five to seven day pulse of water will be at full powerhouse capacity, or
about 25,000 cubic feet per second. During this peak, the dam’s selective water
withdrawal gates will remain uninstalled, according to the SOR. That will allow
river operators to conserve warmer surface water that will be used “during the
second descending limb of the second peak.”
will then briefly drop to a level that would result in flows at Bonners Ferry
of about 18 kcfs until the second peak begins.
elevation snowmelt in the Kootenai River basin will trigger the second pulse,
bringing discharge at the dam up to full powerhouse capacity (depending on
local conditions in the river at Bonners Ferry).
the end of this second peak, warmer water will be released to raise the river
to sturgeon spawning temperature of 8 to 10 degrees Celsius (about 46 to 50
degrees Fahrenheit). The second peak will last 7 to 14 days, or until the
sturgeon volume is exhausted, according to the SOR.
that time, discharge from the dam will be set at bull trout minimum flows of no
less than 9 kcfs.
the sturgeon and bull trout operations are complete, discharge at the dam will
drop to 6,000 cubic feet per second in September and into the first week of
November to accommodate a long-term Kootenai River restoration project.
Ireland, fish and wildlife director for the Kootenai Tribe of Idaho, and Joel
Fenolio, Upper Columbia River senior water manager with the U.S. Army Corps of
Engineers, proposed lower flows to accommodate Kootenai River habitat
restoration work near Bonners Ferry that is dubbed Lower Meander Project. While
this particular work will go on for two years, the entire habitat project had actually
begun in 2011, Ireland told TMT.
SOR 2017-1: http://www.nwd-wc.usace.army.mil/tmt/agendas/2017/0510_2017_KRHRP_SOR_02_16_17.pdf.
Lower Meander Project will “improve habitat conditions in the Kootenai River to
help adult sturgeon migrate upstream, improve spawning habitat, increase
juvenile rearing habitat, and improve overall ecosystem function,” the SOR
work includes bank structures for bank stability, but it will also help maintain
deep pools, Ireland said.
will establish a sequence of high-quality and deeper
pools in the river to support sturgeon migration to upstream habitats in the
Braided and Canyon reaches, the SOR continues. Fill and plantings will be added
to existing islands to promote riparian development and provide food web
support. Workers will also add woody debris in side channels and along bank
margins to improve habitat complexity.
May 20, 2016, “Elevated Flows At Libby Dam Aimed At Benefitting Kootenai River