CPW conducting major project to restore native fish to Colorado creek

Aquatic biologists plan to conduct a reclamation project on South Mesa Creek in Montrose County during the week of September 16.

The project will apply a piscicide called rotenone to the creek along P16 road to remove non-native cutthroat trout. The project goal is to restore native Colorado River cutthroat trout within the creek. CPW crews (along with help from the Bureau of Land Management) will conduct removal efforts of non-native fish.

Historically, Yellowstone cutthroat trout were stocked into South Mesa Creek and reproduced with the native Colorado River cutthroat, creating hybridized cutthroat trout, according to Eric Gardunio, a CPW Area Aquatic Biologist. CPW says that Colorado River Cutthroat Trout now occupy only about 11% of their historic habitat.

The project aims to remove the hybridized cutthroat trout and restock the creek with native Colorado River cutthroat trout. The non-native trout must be removed before establishing and stocking the native population to ensure they do not hybridize.

"These projects are critical to CPW’s goals of conserving native species, and South Mesa Creek offers a great place for our native cutthroat to thrive," Gardunio said in a press release from CPW.

Aquatic biologists will use EPA-registered piscicide rotenone, an organic chemical used worldwide for fish management projects, to remove non-native fish. CPW has used rotenone for over 80 years to remove fish in lakes and streams.

Access to South Mesa Creek will be temporarily restricted during the project. People also may notice a slight discoloration or a green tint of the water from an inert dye used to trace water flow while rotenone is being used. The treated areas will be empty of fish until at least next summer.

According to CPW, this restoration work is done to "assure that native trout remain a sustainable and important part of Colorado's natural environment."