Mitigation for the Construction and Operation of Libby Dam

Chapter 1
Physical and Biological Monitoring in the Montana Portion of the Kootenai
River Basin
Abstract
Montana Fish, Wildlife & Parks (FWP) uses a combination of diverse techniques to
collect a variety of physical and biological data within the Kootenai River Subbasin. These
data serve several purposes including: the development and refinement of models used in
management of water resources and operation of Libby Dam; investigations into the limiting
factors of native fish populations, gathering basic life history information, tracking trends in
endangered, threatened species, and the assessment of restoration or management activities
intended to restore native fishes and their habitats. Bull trout core areas for the Koocanusa
population include Grave and Skookumchuck creeks and the Wigwam and White rivers, with
the majority of the spawning located in the tributaries located in British Columbia. Bull trout
redd counts in Grave Creek and the Wigwam River have significantly increased since 1995.
Bull trout core areas in the Kootenai River downstream of Libby Dam include Quartz, Pipe,
Bear (Libby Creek drainage), O’Brien creeks and the West Fisher River. Bull trout redd
counts within these individual core streams have been variable over the past several years,
and have not increased in proportion to bull trout redd counts upstream of Libby Dam.
Montana FWP conducted an adult bull trout population estimate below Libby Dam in the
spring of 2004 using mark recapture techniques and estimated a total of 920 adult bull trout,
which represented 263 bull trout per mile. We have monitored the relative abundance of
burbot in the stilling basin below Libby Dam using hoop traps since 1994. We captured a
total of 3 burbot during the 03-04 trapping seasons which represented the lowest total catch
and catch per effort (burbot per trap day) since trapping began in the 1994-95 trapping
season. During mid-November 2003, Montana FWP began a detailed field study to
investigate the life history of burbot in Libby Reservoir (named Lake Koocanusa). During
the period from November 14 to April 26, 2004 we completed 1887 trap-days, and caught a
total of 127 burbot at 10 locations throughout the reservoir. Burbot catch at all trapping
locations averaged 0.064 fish per trap-day. Mean burbot catch was highest near the mouth of
Cripple Horse Creek and lowest near the mouth of Dodge Creek. We surgically implanted
28 coded acoustic and 12 combined radio/acoustic tags in burbot at 8 trapping sites. Each
tag had a unique frequency or code to allow for individual fish identification. We estimated
that the mean home range was 6524 m (range 166 – 27470 m) for the 30 tagged burbot that
were relocated after release. The mean estimated depth of burbot that were relocated during
daylight searches using acoustic gear was 35.6 m, which was significantly deeper than the
mean depth at which we operated traps (14.8 m). We did not detect clear upstream or
downstream movement patterns in the tagged fish relocations. Of the 40 tagged burbot,
however, many were observed extensively utilizing the submerged Kootenai River channel
and floodplain during daylight hours. We sampled macro-invertebrates at the Libby Creek
Upper Cleveland Project and the Grave Creek Phase I Restoration Projects to assess the
macroinvertebrate community response to these two restoration projects. We used the
following metrics for comparison before and after restoration activities: taxa richness, EPT
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