Bozeman — This month Montana Fish, Wildlife & Parks will be conducting a rotenone treatment of the North Fork of Spanish Creek.
This is the second rotenone treatment as part of a multi-phased project to remove non-native fish and restore native westslope cutthroat trout to the North Fork of Spanish Creek. Rotenone is a naturally derived substance commonly used in fish restoration efforts that is toxic to gill-breathing animals and breaks down quickly in the aquatic environment.
Westslope cutthroat trout are native to Montana but have experienced substantial declines in distribution and abundance throughout their historical range due to habitat degradation and hybridization with rainbow trout. However, the results of this restoration project will more than double the number of stream miles occupied by westslope cutthroat trout in the Gallatin River drainage.
From Aug. 5 to 7, FWP will be assessing stream flow rates using dye tablets to determine the rate at which rotenone will be carried downstream. The dye will not impact the water’s suitability for fish or human consumption.
The rotenone treatments are scheduled to begin Aug. 10 and could last until Aug. 21. Non-native fish will be removed above a constructed barrier on private land several miles upstream of the Spanish Creek Road. In addition to treating all streams above the barrier, FWP will also treat Chiquita and Big Brother lakes.
Rotenone usually does not pose a significant risk to humans, but people should avoid consuming water from the treatment area during this period. Signs will be posted around the lakes during and immediately following treatment. A detox station will be installed at the barrier, so the rotenone will not impact the water’s suitability for fish or human consumption downstream of the project.
The South Fork of Spanish Creek, accessed from the trailhead at the end of the Spanish Creek Road, will not be impacted by the treatment.