In fall 2008 Regional Fisheries crews completed rotenone treatments of Lower Big Hawk Lake and approximately four miles of Graves Creek from the confluence of the outlet streams from Black and Blackfoot lakes downstream to the barrier waterfall above Handkerchief Lake. Removal of nonnative trout from these waters is necessary to eliminate the threat of hybridization with the remaining populations of westslope cutthroat trout in the South Fork Flathead drainage.
Helicopter sling loads were used to transport equipment and rotenone to Lower Big Hawk Lake. Rotenone application at the lake took approximately five hours using a boat and venturi system. Drip stations at two inlet streams and below the outlet of the lake on Jones Creek were operated for eight hours. A detox station was flown in to Jones Creek near the confluence with Aeneas Creek to neutralize rotenone.
In early summer 2009, three age classes of westslope cutthroat trout will be stocked to reestablish the recreational fishery and fisheries crews will begin post-treatment monitoring of insect, plankton, and amphibian communities.
The rotenone treatment project on Graves Creek was conducted in collaboration with Montana State University graduate research on environmental degradation of rotenone. Results from this work will be useful for future rotenone projects and post-treatment monitoring will allow biologists to document recovery of these communities.
View photos of treatment at Big Hawk Lake: