From Colorado Parks and Wildlife via The Pagosa Sun:
Colorado Parks and Wild- life (CPW) is continuing its work to make southwest Colorado a center for native cutthroat trout restoration. The agency will start a recla- mation project near the top of Wolf Creek Pass Sept. 11-13 to bring the native cold-water fish back to part of its native habitat.
Native cutthroat trout were nearly eliminated from Colorado during the pioneer days when water quality in many rivers and streams became polluted due to run off from timber and mining operations.
Also at that time, non-native trout — rainbows, browns and brook — were introduced to Colorado waters and muscled out the native trout. Fortunately, for more than 30 years CPW biologists searched for these indigenous fish and found sev- eral isolated populations in remote streams in the San Juan Basin.
“We’ve been working on cutthroat trout projects in this part of the state for more than 30 years and we’ve made great progress in restor- ing these fish to their native waters,” said Jim White, aquatic biologist in Durango.
Native cutthroat are only found and stocked in Colorado’s headwaters areas.
To re-establish native fish, CPW treats streams with an EPA-approved chemical to eliminate any non-native fish. In September, biologists will treat 1.5 miles of the south fork of Wolf Creek. The chemical, rotenone, has been used safely for years around the world for aquatic management projects. Used properly, it poses no threat to human health. On all stream projects, CPW adds another chemical to the water at the terminus of the treatment area to neutralize the effects of the rotenone. The treatment will be done on Sept. 12 and CPW staff will stay through the next day to monitor the water.
This tributary of Wolf Creek was selected for the project because it provides excellent trout habitat and it is separated by large natural barriers from the main stem of Wolf Creek. The barriers prevent non-native fish from moving upstream into the treated area.
This year is an ideal time for the treatment because the water level in the stream is low and easy to treat. The treated area will be void of fish until next summer. After the spring run-off in 2019, CPW biologists will check the stream to assure non-native fish have been eliminated. If none are found, the native cutthroats will be stocked next summer.
This and other native trout restoration projects are done in coop- eration with the San Juan National Forest.
Native cutthroat trout are restored in headwater streams where the water is pristine, free of whirl- ing disease and non-native fish. Pure native cutthroat trout are not stocked in major rivers because they cannot compete with established non-native rainbow and brown trout populations.
“Colorado Parks and Wildlife is dedicated to maintaining our state’s native species,” said John Alves, senior aquatic biologist for CPW’s Southwest Region. “Restoration work is done to assure that native trout remain a sustainable and important part of Colorado’s natural environment.”
North of Durango, CPW is in the final step of reintroducing native cutthroats into nearly 30 miles of stream in the Hermosa Creek area. The final section will be restocked next summer.
To learn more about CPW’s work to restore native cutthroat trout throughout the state, go to http:// cpw.state.co.us/learn/Pages/Re-searchCutthroatTrout.aspx.