Sawyer chain saws are buzzing at select spots around Durango as fire crews trim trees and clear shrubs to protect the city from wildfire.

On Thursday, three different crews were busy with fire mitigation work. Through the summer, they have treated areas on Eastern Heights Park, Tanque Verde, Folsom Park and several other locations. Some residents have asked the city about the work.

“What our goal is is to reduce the risk of fire and the severity of a fire if a fire were to come into city limits,” said Amy Schwarzbach, natural resources manager for the city of Durango.

The city’s fire mitigation program was organized by Fire Adapted Durango, a partnership between Durango Parks and Recreation, Durango Fire Protection District, La Plata County, the Bureau of Land Management, Colorado State Forest Service and other entities.

Crews are cutting shrubs and lower tree limbs and hauling and piling those materials to allow them to dry. The piles will likely remain where they are for more than a year. Then, when there is sufficient snowfall and plenty of moisture, crews will return to burn the piles in a safe manner.

“And that means people can expect to see cutting and piling, and then the piles remaining in place until conditions are appropriate,” Schwarzbach said. “That’s where the city partners with Durango Fire Protection District, Colorado Division of Fire Prevention and Control and the BLM to burn those piles.”

The piles are only burned under the right moisture conditions and a state permit is required to conduct the burns, she said.

The main target for the city’s summer fire mitigation efforts is Gambel oak, a dense, shrubby plant that has a habit of shooting upward to form walls of vegetation that are “really darn flammable” when still young, Schwarzbach said.

“What we’re doing is following Colorado State Forest Service standards to create a mosaic of vegetation out there. Which means you break up your continuity of fuels,” she said.

Cutting breaks into areas of Gambel oak reduces a fire’s chance of spreading, she said. Crews will also trim the lower limbs off trees that could be susceptible to open flames.

The strategy is to reduce ladder fuels, and thus, reduce the destructive capabilities of a possible fire. Clearing ladder fuels also allows firefighters to safely get into areas to fight fires, Schwarzbach said.

“Thinking just like rungs on a ladder you climb up as a human being, a fire starts on the ground, works its way up a shrub and then up into a tree,” she said. “You’ve got a much more intense fire. That’s why we’re getting rid of the ladder fuels by trimming up the lower branches on trees, leaving the trees there, and then breaking the continuity of fuels.”

Cutting back brush and low-hanging branches can mitigate fire hazards, but the process also serves to promote forest health, Pete Stockwell, wildfire mitigation specialist with Durango Fire Protection District, said.

“When coupled with mitigation, it involves leaving a diverse set of fuels. We can’t just cut everything that we decide is prone to fire,” he said.

Wildfire mitigation can support water quality improvements by protecting the Animas and Florida rivers from debris and runoff that could pollute it in the event of a wildfire, he said.

And when it comes to cutting trees, fire mitigation crews are conscious about leaving a diversity of trees and plant life. Piñon juniper, for example, burns easily, but rather than removing all of it, crews work to reduce the amount of ladder fuels around them.

“If it were just fire mitigation we’d go out and we’d (leave) all the ponderosas because they tend to do well in fire,” Stockwell said. “But we have to incorporate leaving some of the serviceberry brush and the mahogany and a lot of the native fuels that we see around here so that the forest is still healthy in terms of water runoff, in terms of ecology.”

The city is taking advantage of two grants, one two-year grant from the Colorado State Forest Service and a four-year grant from the BLM, to treat about 45 acres of open space in and near Durango. Schwarzbach said the cost of treatment per acre varies based on terrain and vegetation.

Costs range from $3,000 to $6,000 per acre. Full-sized vehicles aren’t capable of reaching most treatment zones, which makes treatments all the more labor intensive for sawyer and chain-saw crews grouped into 10 separate treatment units.

Despite the summer monsoon’s arrival and its recent rains, things aren’t simply “hunky-dory” when it comes to fire danger, Schwarzbach said.

“Rain is wonderful, we always need rain, but we need to be doing fire mitigation also,” she said.

Last summer, fire crews performed wildfire mitigation work in Edgemont. Last fall, wildfire mitigation was performed above the Purple Cliffs unmanaged camp, Stockwell said.

“And they were creating, basically, a fire break behind the homeless camp there should a fire start there, which it seems they do occasionally,” he said. “Which would allow us a chance to kind of suppress that fire or hold that fire at that fuel break behind the Purple Cliffs camp.”

He said more entities are collaborating for wildfire mitigation work in La Plata County and in Durango this year. He said the county is serving as the project manager and that he appreciates the La Plata County Office of Emergency Management’s support in area wildfire mitigation efforts.

“It’s been a nice change of pace to have the collaboration between all these entities and the support of the office of emergency management,” he said.

cburney@durangoherald.com