Plans call for Libby Dam spill test to help white sturgeon
As far as biologists can tell, fewer than 500 adults remain among the population of white sturgeon in the Kootenai River.
In wildlife terms, that’s not a whole lot of fish – “especially when they’re not reproducing,” said Jason Flory of the U.S. Fish and Wildlife Service’s Northern Idaho Field Office.
To increase chances of survival for the unique landlocked species of fish, an increased spill operation at Libby Dam is planned for next spring.
“The aim of this spill test is hopefully to coax the fish to migrate further upstream from Bonners Ferry to the ‘canyon reach’ in Montana,” Flory said. “Providing more flows and more depth will allow the sturgeon to migrate where the area is rocky substrate.”
Currently, the sturgeon have been spawning downstream of Bonners Ferry, Idaho, in what is called the “meander reach.” Flory said that is a problem because that stretch of the river features a streambed of sand and silt. The sturgeon’s fertilized eggs become adhesive, stick to the sand and silt, end up buried and die.
The “canyon reach” extends from Libby Dam to the Moyie River and the “braided reach” runs from Moyie River to Bonners Ferry. The “meander reach” goes from below Bonners Ferry to the river’s confluence with Kootenay Lake in British Columbia.
Both the canyon and braided reach portions of the river are composed primarily of gravel and cobble streambeds – more suitable for spawning.
Regional biologists – including Flory – determined that the sturgeon did not benefit from the 2008 and 2009 flow operations. A settlement agreement to a 2006 federal biological opinion requires the U.S. Army Corps of Engineers and Bonneville Power Administration to provide river flows, depths, temperatures and gravels that encourage the sturgeon to swim upriver for spawning.
Since the dam operations did not meet the criteria for sturgeon over the last two years, additional water will be released over the Libby Dam spillway for up to one week during late spring from 2010 through 2012. Biologists will evaluate the effects of the extra water on migration and spawning.
Officials said the spills will occur sometime between late May and late June, depending on water supply forecast, runoff projections, water temperature and Koocanusa reservoir elevation. The Corps will coordinate the timing and other details with federal, state and tribal officials as well as other regional interests. The Corps will hold its annual public meeting this coming April or May to provide more detail on the 2010 operational plan.
“The Corps' primary consideration is minimizing risk to human life, health and safety, while meeting Libby Dam's multiple purposes and responsibilities,” Libby Dam operations manager Mick Shea said in a press release. “The spill operation will be closely monitored to ensure that the spill test does not exceed flood stage below Libby Dam.”
BPA funds habitat restoration and hatchery improvements through sales of hydropower generated at Libby Dam and 30 other dams in the Columbia Basin.
Kootenai River white sturgeon, which are not found above Kootenai Falls, were listed as an endangered species in September 1994. They have not produced a significant number of offspring in the wild since 1974. The dam was completed that same year and it has been determined that the flood control and hydropower operations altered the sturgeon’s habitat.
Historical documents, which do not provide many details, indicate that an area below Kootenai Falls between Libby and Troy was once a spawning area for the Kootenai white sturgeon.
Biologists, including Jason Flory of the U.S. Fish and Wildlife Service, are trying to investigate just how that data was collected.
These days, a high-tech approach to following fish has been established on the Kootenai River.
First, biologists from various agencies went and caught sturgeon, pulled them onto a boat and inserted a sonic tag into their body cavity. The fish were released and the tags emit a signal at regular intervals.
Along the river, receivers were installed in various spots to collect data from the signals.
“Since 2004 or so, those crews have put up a pretty good array of receivers from Bonners Ferry all the way down to Kootenay Lake in British Columbia,” Flory said. “Anytime a fish passes one of those receivers, it logs in the fish number and time and keeps on logging that.”
Crews then go out, hook up a cable to the river-side receiver and download data onto computers.
“With such an elaborate array of receivers, you can go back and get a pretty detailed picture of what these fish are doing,” Flory said.
Prior to the sonic tags and on-shore receivers, information was collected through radio telemetry. That process involved biologists riding around in antenna-equiped boats trying to detect signals.