Higher flows, a double pulse of spring water and a long-term habitat project in the Kootenai River resulted this year in a 20 percent increase in sturgeon moving upstream of Bonners Ferry to spawn, according to a review last month of 2017 operations to aid white sturgeon and bull trout downstream of Libby Dam.
An April to August water supply volume of 8.19 million acre feet, 139 percent of average, spurred river managers to initiate a double pulse of water from Libby Dam in mid-May designed to encourage wild Kootenai River white sturgeon to move upstream to spawn, and later to initiate a bull trout minimum flow of 9,000 cubic feet per second downstream of the dam.
The first pulse of water for the sturgeon was to encourage the movement and the second pulse was to trigger further movement upstream and spawning, according to Jason Flory of the U.S. Fish and Wildlife Service.
Overall, 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 sturgeon response was what we were looking for,” Flory said. “We saw a 20 percent response (over the previous five-year average) in the number of tagged sturgeon migrating above Bonners Ferry, and I think we can assume all of them were moving up to spawn.”
Flory spoke at the Technical Management Team’s Year End Review last month in Portland.
TMT is made up of fisheries and hydro/reservoir managers from state, federal and tribal agencies. Every December the group looks back at actions taken during spring and summer in managing Columbia and Snake river federal hydro/fish operations. Flory’s presentation was among nine reviewed in the day-long session.
Flory also gave credit to the Kootenai River habitat restoration project near Bonners Ferry that is “mostly in place” as one reason why the sturgeon are beginning to move and to spawn.
Still, “we will have to wait four or five years until we know for sure if there’s been an uptick in the number of juveniles,” Flory said.
The sturgeon pulses this year discharged 1.2 MAF from Libby Dam. The operation is defined in the Service’s 2006 biological opinion for Libby operations, covering both sturgeon and bull trout, which are listed under the federal Endangered Species Act.
The multi-year Kootenai River habitat restoration project led by the Kootenai Tribe of Idaho focuses on the Idaho portion of the Kootenai River, Flory said, speaking for Sue Ireland, fish and wildlife director for the Tribe, who could not attend the Year End Review.
“The project has changed pool depths, particularly upstream of Bonners Ferry,” Flory said. “The idea is to create big pools upstream and move the migration of sturgeon into upstream areas for spawning.”
He said the long-term project, in addition to adding pool depth, has also added woody debris, reconnected side channels, recreated flood plains and enhanced riparian areas.
In early May, Ireland approached TMT proposing lower flows down to six kcfs in September and into the first week of November to accommodate the habitat work near Bonners Ferry, called the Lower Meander Project.
The 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,” she said in a Systems Operations Request.
The work included bank structures for bank stability, but the work also helped maintain deep pools.
Workers 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 said.
The work began by the Tribe in 2011 and is due to officially end in 2018. However, the Tribe could in the near future look at more habitat work in the river.
“There are still a few planned projects in 2018 and after that there are a few downstream projects and other proposals on the table,” Flory said.