DILLON – Staff at Montana Fish, Wildlife & Parks are seeking comments from the public on a proposal to remove non-native trout from a portion of Cottonwood Creek near Dillon.  

The proposal includes removing hybrids of cutthroat trout and brook trout from a 2.7-mile section of the creek and replacing them with westslope cutthroat trout.  
Westslope cutthroat trout presently occupy less than 4 percent of their historic habitat within the Beaverhead watershed. Cottonwood Creek is one of eight streams within the watershed that still support an unaltered westslope cutthroat trout population. But it in Cottonwood Creek, this is limited to an estimated 520 fish that occupy less than a mile of stream above a natural waterfall.  

Westslope cutthroat trout have been petitioned for listing under the Endangered Species Act, and FWP staff in southwest Montana have a goal of restoring westslope cutthroat trout to 20 percent of their historic range in order to prevent the need for listing under the act.  

In 2020, a wooden fish barrier was installed on the lower end of Cottonwood Creek in preparation for this project. Biologists would use rotenone to remove the non-native fish in the 2.7-mile section of stream between the barrier and the waterfall.  
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. Rotenone does not pose a significant risk to recreationists or other water users. FWP staff would sign and close the project area during the treatment, and a detoxification station would operate below the treatment area.  

Removing non-native trout and restoring native westslope cutthroats would increase the likelihood of long-term survival for this population of westslope cutthroat trout.  

The proposal is described in detail in an environmental assessment, which can be viewed online at https://go.usa.gov/x6NkN. Comments can be emailed to rkreiner@mt.gov or mailed to: 

Ryan Kreiner 
730 ½ Montana Street 
Dillon, MT 59725 

Comments will be accepted until 5 p.m. on July 5, 2021.