Click the link to read the article on the Sky-Hi News website (Izzy Wagner). Here’s an excerpt:
September 9, 2025
13 years ago, Colorado’s state fish could only be found in a single stream in the entire state. Today, a coalition of agencies and experts are working to change that. The Poudre Headwaters Project is a 10 to 12-year effort led by Rocky Mountain National Park and Colorado Parks and Wildlife, among other organizations, to restore the greenback cutthroat trout to its native waters — about 40 miles of streams in parts of Rocky Mountain National Park and the Arapaho National Forest…
For decades, the National Park Service and state fisheries stocked millions of fish, mostly brook trout, in the native waters of the greenbacks. But once brook trout have established themselves in a stream, they will outcompete greenbacks for food and habitat, Clatterbuck said. Restoring native greenbacks requires killing off the non-native brook trout that have long threatened their survival. To kill the fish, crews must apply the pesticide rotenone to streams with invasive brook trout and other non-natives. Rotenone is a dangerous chemical in high concentrations, but it has been widely used by fisheries for decades and is carefully managed when applied to streams…The pesticide specifically targets aquatic species, making it the ideal treatment method for fish removal. Consuming rotenone-treated fish is unlikely to poison a mammal, Clatterbuck said…
Once the areas are confirmed to be free of non-native trout, biologists will reintroduce the native greenback cutthroat trout to its original habitat in the headwaters of the Cache la Poudre River, according to park officials…Colorado State University Professor Robert Behnke reported that once brook trout gained access to streams, greenback cutthroat trout were virtually gone within five years. In the 1960s, Behnke spearheaded efforts to restore greenback cutthroat trout to streams of their native range east of the Continental Divide. Since then, fisheries have worked to build fish barriers, often in the form of small dams, near the downstream ends of headwater streams to protect native fish while applying chemicals to kill off brook trout upstream. However, none of these projects have been able to prevent non-native trout invasion long term. Clatterbuck is hopeful that with time and collaboration, this new restoration project will build a metapopulation, or a network of connected subpopulations that can strengthen the species’ genetic diversity and resilience.
