“Once removed, native Greenback cutthroat trout will be reintroduced into its native range in the headwaters of the Cache la Poudre River”
Another phase of the Poudre Headwaters Project is set to start during the week of August 24-30 on the west side of Rocky Mountain National Park, the Park announced in a statement Wednesday, Aug. 5.
The project is key to helping one kind of trout thrive in its native waters.
“This project involves the removal of all non-native fish from the Grand Ditch and upstream and downstream tributaries inside the park,” Kyle Patterson with RMNP said in the statement. “Once removed, native Greenback cutthroat trout will be reintroduced into its native range in the headwaters of the Cache la Poudre River.”
Young greenback trout require food, space and protection from non-native predators and competitors, like brook trout, which outcompete greenbacks, according to Patterson.
“Removal of brook trout is a key factor for recovery success,” Patterson said.
The first phase of this project inside RMNP took place during August 2025.
“This year’s project will be very similar to last year’s project,” Patterson said. “Because of the level of activity associated with the implementation of the Poudre Headwaters Project, all areas and trails within the project zone will be closed to all uses beginning on Aug. 24 through Aug. 30.”
The Colorado River Trail and the Grand Ditch will be closed.
“Aquatic biologists will apply a piscicide called rotenone to remove the non-native fish to the 14.3-mile Grand Ditch system and its upstream and downstream tributaries,” Patterson said. “Rotenone is commonly used by state and federal land management agencies. This project will be led by biologists with the U.S. Forest Service.”
While this project is underway, the following trails will remain open:
- East Inlet Trail, North Inlet/Tonohutu Trail, Green Mountain Trail, Coyote Valley Trail, Onahu Trail, and Timber Lake Trail.
- The Holzwarth Historic Site and Harbison Meadows Picnic Area will also remain open.
Fishing access will remain open in all areas along the Colorado River located south of the Colorado River Trailhead, including near the Holzwarth Historic Site and Coyote Valley.
Other partners include Colorado Parks and Wildlife and U.S. Fish and Wildlife Service. This project is possible thanks to support provided by Trout Unlimited and Rocky Mountain Conservancy.
For more information about Rocky Mountain National Park visit www.nps.gov/romo or call the park’s Information Office at 970-586-1206.
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