HERMOSA PARK – The heavy equipment working on the East Fork of Hermosa Creek this month was surprisingly delicate and precise as it transformed eroded streambanks and shallow braided waters into prime habitat for Colorado River cutthroat trout.
The San Juan National Forest hired Durango contractors G2 and AJ Construction to complete 500 feet of streambank stabilization in preparation for reintroduction of native Colorado River cutthroat on a stretch of the creek where non-native fish have been removed.
“It’s important to conduct these operations at times when we have low flows and no fish,” said Clay Kampf, fisheries biologist for the San Juan National Forest Columbine District. “We started at the headwaters of each tributary and worked our way downstream to make sure there were always other fishing opportunities.”
Under the direction of Kampf, Grady James, equipment operator with AJ Construction, spent September maneuvering rocks and logs into place to reinforce streambanks and create small waterfalls and deep pools. The goals were clean water and a diversity of habitat for all seasons.
“When the creek takes a corner, and an unstable bank erodes, sediment washes into the water and impacts the ability of fish to survive in many ways,” Kampf said. “Corners are high-stress points so we place large rocks there to protect the banks during higher flows.”
This fall’s water level was only about three to five cubic feet per second, which offered an opportune time to conduct improvements, but the project was designed for a wide diversity of flows. While spring flows of up to 40 to 50 cfs in the East Fork of Hermosa Creek threaten habitat by eroding the banks, very low flows in winter also endanger the fish.
“Keeping water moving in winter keeps it from freezing, which has been the biggest limiting factor for long-term cutthroat survival,” Kampf said. “Constricting the channel and creating small pour-overs increase the winter flow levels.”
Buried logs are effective for stabilizing banks where the stream splits and creates shallow stretches that offer spawning habitat in the spring. But where the creek had divided into multiple channels, rocks were used to divert water back into the main channel to keep flows steady.
Encouraging vegetation is also important for stream stabilization. When the heavy equipment scooped up grass and forbs to make way for placement of rocks and logs, its giant claw replanted the native vegetation with the skill of a seasoned gardener.
“We retain any disturbed vegetation and replant it nearby,” Kampf said. “We avoid disturbing any established willows, which in this stretch are about five to 10 years old.”
Kampf also hopes nature’s furry engineers will return to the area and help with recovery.
“There were beavers, but they moved upstream and downstream during disturbance from the project,” Kampf said. “If the beavers return and flood the area, they will create additional overwintering and larger pools for the cutthroat.”
The Forest Service will closely monitor the project area for three years, keeping an eye out for noxious weeds. Volunteers with the Durango Chapter of Trout Unlimited will help the agency later this fall to plant additional native grass and forb seeds and alder/willow cuttings along the banks to further revegetate the area.
“Our goals are to improve water quality and mimic natural features that will aid in the conservation of the Colorado River cutthroat, which will, in turn, improve recreational fishing,” Kampf said.
Ann Bond is the public affairs specialist for the San Juan National Forest. Reach her at firstname.lastname@example.org.