Colorado cutthroat trout, native to the state, is making a comeback in the headwaters of Hermosa Creek.
The fish, also native to Utah, Wyoming and New Mexico, is found in only about 14 percent of its historic habitat, said Clay Kampf, a San Juan National Forest biologist.
The cutthroat was hurt by competition from non-native brook trout and a tendency to hybridize with rainbow trout.
Now, there are efforts across Colorado to re-establish it, and the area in the Hermosa Creek drainage will be one of the largest, said Jim White, a Colorado Parks and Wildlife biologist.
The presence of the fish helped local advocates push through the legislation designating the Hermosa Creek Wilderness and Special Management Area. Both areas encompass more than 100,000 acres north-northwest of Durango.
In 1991, Hermosa headwaters were home to brook trout, not cutthroat.
But since then, the cutthroat has been re-established in 17 miles of the east fork and the main stem of the headwaters, Kampf said.
When the project is complete, the fish will occupy 23 miles of creek upstream from the confluence of the east fork and the main stem.
In early August, Colorado Parks and Wildlife, Trout Unlimited and the Forest Service will begin establishing the fish in three miles of Sig and Relay creeks. Non-native fish will be removed, and the cutthroats added.
The Forest Service will build waterfalls to prevent non-native fish from getting into cutthroat habitat, Kampf said.
"Colorado cutthroat do not compete with non-native fish at all," White said.
Currently, areas designated as cutthroat habitat are catch-and-release, and the Forest Service is considering other changes to help protect habitat. Installing culverts in areas where people and vehicles are crossing the creek could limit the amount of sediment in the water.
These improvements could be written into the Hermosa Wilderness and Special Management Area plan.