Next week, Colorado Parks and Wildlife officials will be treating a two-mile section of the East Fork of Hermosa Creek as part of ongoing efforts to eliminate invasive fish species and restore native Colorado River cutthroat trout to the watershed.
The section, which stretches from below Sig Creek Falls to just above the confluence on the main stem, will be treated with an organic pisicide, Rotenone, to rid the creek of brook trout.
Rotenone poses no threat to terrestrial wildlife or humans, according to a news release issued Monday by Parks and Wildlife. Biologists also plan to use a neutralizing agent just below the treatment area to prevent any fish kills downstream.
“It’s important to do what we can to ensure that we have native trout and they can thrive in Colorado water, because in our age of climate change, our age of forest fires, there is the risk of having them wiped out by catastrophic events,” said Buck Skillen with Trout Unlimited, a stakeholder in the project along with Parks and Wildlife and the U.S. Forest Service.
“This is one step in creating roughly 23 miles of cutthroat water on the East Fork and main stem of Hermosa Creek,” he said.
Signs will be posted at areas closed to the public during the process, which is slated from Aug. 2 to Aug. 3.
As the agency did last summer when this section was treated, Parks and Wildlife crews will use a neutralizing agent, which may cause a rusty discoloration of the water temporarily, below the treatment area to prevent fish kills downstream.
A rock barrier will be installed at the completed section to prevent the infiltration of non-native fish species.
If no brook trout are found in the section when it is checked later this summer, Colorado River cutthroat could be stocked this fall.
Hermosa Creek and the upper section above Sig Falls are open to anglers, but they must release cutthroat trout.
The project is among the largest native trout restoration projects in the state, and it has been underway since the early 1990s. Since then, Parks and Wildlife has been able to restore cutthroat populations to the upper East Fork and the main stem above Hotel Draw.
When complete, officials hope trout are restored throughout the watershed, ending just below the confluence of the East Fork and main stem.
“This project is especially important because it connects several streams in a large, complex watershed,” Jim White, an aquatic biologist for Parks and Wildlife, said in a statement. “The connectivity provides what biologists call ‘resiliency’ to the system. There are more stream miles available to the fish which allows for more genetic exchange. It also makes the fish less susceptible to disease and to large sedimentation events such as fires, mudslides or avalanches.”
jpace@durangoherald.com