A fire burning on Missionary Ridge north of Durango was 20.7 acres and 90% contained as of Thursday night, according to the San Juan National Forest.
The 186 Fire, while still active, is not expected to grow, said Chris Tipton, fire management officer for the Columbine Ranger District.
Crews completed a fire line on the west side of the blaze, and retardant lines were holding well, the public lands agency wrote in a Facebook post. Ground crews were being supported by a helicopter in extinguishing hot spots on the east side.
“Crews are going to stay on scene for the foreseeable future until we are confident we can pull folks off and not have any potential for burn-through for the fire to rekindle,” Tipton said. “Smoke is going to be visible on the fire for probably several days to come, though it is diminishing substantially over the last couple burn periods.”
A helicopter, air attack plane, two air tankers and about 50 firefighters were available this week to work the fire, said Denise Alonzo, spokeswoman for the San Juan National Forest.
The fire was burning in an area with thick, heavy debris on the ground and “standing dead snags,” which posed a risk to firefighters. The debris was preventing firefighters from constructing a fire line in some areas.
“Because of the snag hazards and heavy fuels and tough terrain, we can’t go in and physically touch the left flank or the eastern flank of the fire because of safety concerns,” Tipton said.
Fire personnel used a heli-tanker Thursday to monitor the east side of the blaze.
Firefighters are not expected to completely extinguish the interior of the fire because of the dangers. Instead, they will build a containment line around the perimeter of the blaze and let the interior burn itself out.
“The public should expect to see smoke from the area for several days until the heavy material burns down, smolders, in the middle of the fire,” Alonzo said earlier this week.
The fire posed no immediate threat to structures, and the weather is “positive” for fighting fires, she said Wednesday morning.
The Forest Service says the 186 Fire is a lightning-caused fire, possibly a holdover from a thunderstorm June 5.
Additional resources were brought in Thursday to prepare for additional lightning and thunderstorms in the region, Tipton said. He reminded people to be careful with campfires and other ignition sources.
“We have fire season every year,” Tipton said. “In spite of how wet of a winter we had, those fuels dry out, are available to burn. ... It’s never a time in June during fire season in ponderosa pine forest to be complacent.”