Rocky Mountain National Park will temporarily close portions of the Kawuneeche Valley Aug. 24-30 as crews carry out the next phase of a multi-year effort to restore native greenback cutthroat trout to the headwaters of the Cache la Poudre River.
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The project, known as the Poudre Headwaters Project, will involve removing non-native brook trout from the Grand Ditch and connected upstream and downstream tributaries on the park’s west side before native greenback cutthroat trout are reintroduced to their historic range.
To accommodate the work, the Colorado River Trail and the Grand Ditch will be closed to all uses from Monday, Aug. 24, through Sunday, Aug. 30. The closures follow the first phase of the project, which was completed in August 2025.
According to Rocky Mountain National Park, young greenback cutthroat trout need food, habitat and protection from non-native fish, particularly brook trout, which outcompete the native species. Removing brook trout is considered a critical step in restoring self-sustaining populations of Colorado’s state fish.
Aquatic biologists will use rotenone, a piscicide commonly used by state and federal land management agencies, to remove non-native fish from the 14.3-mile Grand Ditch system and its tributaries. The Forest Service reports that birds or mammals that may consume treated water or fish will not be impacted by rotenone because it targets only gill-breathing animals.
The work will be led by the U.S. Forest Service in partnership with Colorado Parks and Wildlife, the U.S. Fish and Wildlife Service, Trout Unlimited and Rocky Mountain Conservancy.
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Several popular destinations will remain accessible during the project. The East Inlet Trail, North Inlet/Tonahutu Trail, Green Mountain Trail, Coyote Valley Trail, Onahu Trail and Timber Lake Trail will remain open, along with the Holzwarth Historic Site and Harbison Meadows Picnic Area.
Fishing access also will remain available along the Colorado River south of the Colorado River Trailhead, including areas near the Holzwarth Historic Site and Coyote Valley.
Completion of all Poudre River Headwaters Project elements is expected to take another 10 to 12 years, according to the Forest Service, but when completed will provide for a connected “metapopulation” of trout across the watershed, which will become the largest such restored native trout habitat in Colorado.
For more information about the project, visit the Forest Service/USDA website at www.fs.usda.gov
Additional information about Rocky Mountain National Park can be found at www.nps.gov/romo.
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