In order to reduce the risk of high-intensity wildfire, improve forest health and wildlife habitat, the Bureau of Land Management Tres Rios Field Office has planned a prescribed fire treatment for up to 717 acres on Animas City Mountain in Durango, Colorado. Dependent on weather and the availability of firefighters to conduct the operation, the prescribed burns could take place as early as the fall of 2021 or in the spring of 2022. An Environmental Assessment which covers this, as well as other treatment areas in La Plata County, has been completed and is available here: Final Environmental Assessment.
Prescribed fires require a comprehensive plan consisting of 21 elements. The plan outlines the methodical process from inception to completion. The Animas City Mountain project is expected to take 2-3 days for ignitions, with additional time to patrol the area and extinguish hot spots. The mountain has been divided into seven units or compartments. Crews are expected to begin burning on the top of the mountain by slowly lighting an edge that has already been thinned with chainsaws. Once a secure edge or “black line” has been established, firefighters ignite the interior of each unit, one unit at a time. The fire then burns back toward the secured, black edge. This methodical approach allows firefighters opportunities to halt ignitions if burning conditions become undesirable. Examples of undesirable conditions are fire behavior that is too active/not active enough, and poor smoke dispersion. Firefighters will also have water on hand to cool things down if fire activity grows beyond a desirable level.
Prescribed fires are watched carefully by firefighters around the burn, lookouts at more distant locations, aerially (helicopters, planes, drones), and with calibrated smoke monitors. These monitors will be placed at locations around the burn to track smoke impacts in real time. The BLM and Colorado Department of Public Health and Environment Air Quality (CPDHE) have been working since 2018 to develop a permit that accomplishes the burn while minimizing smoke impacts to the surrounding area. Prescribed fire smoke may affect your health. For more information, visit https://www.colorado.gov/pacific/cdphe/wood-smoke-and-health. Prescribed fires are a tool to minimize smoke impacts to communities by careful selection of when fires burn and when they stop. Firefighters utilize compartments to halt the fire from spreading overnight, whereas wildfire continue to burn overnight when smoke is likely to settle into low lying areas where communities are located. Residual smoke from the interior areas of the compartments is anticipated, but the goal is to start early in the day and stop early in the evening to give material as much time as possible to be consumed before night-time cooling occurs and smoke sinks into the valley.
Ideal timing (windows) for the project occurs during the Spring and Fall when conditions are more favorable for low-intensity fire. Fuel (vegetation) and weather conditions must fall within a predetermined “prescription” that is known to yield desirable results while still being controllable by the fire personnel conducting the burn. Dissipation of smoke is also part of the prescription. Prescription development has been done by local fire experts who utilize fire behavior computer modeling software combined with decades of experience conducting prescribed burn in southwest Colorado.
This project is a coordinated effort between the federal/county/local government, NGOs, emergency managers, fire departments, public health officials, state smoke regulators and nearby residents. The burn is planned to take place over the course of 2-3 days. Brief closure of Animas City Mountain during the ignitions will occur for public and firefighter safety. The containment lines used for the project will consist of BLM designated trails. The units will be ignited using a combination of ground and aerial resources and will be patrolled/mopped up until out.
The project is part of the BLM’s ongoing commitment to protecting human health and safety while maintaining or enhancing forest and woodland health and functionality. The Animas City Mountain area was previously masticated in 2010 which altered the vertical structure of the forest stand to reduce the risk of catastrophic fire. Mastication is a treatment method where the understory is mowed and mulched with a large machine. The mulched material slowly decomposes, while the understory regrows. Mastication and prescribed fire are effective in preventing fires from leaving the ground and becoming “crown” fires where the entire trees or stand of trees burn. Treatments thin and remove some of the large dense understory or “ladder fuels”.
Vegetation, however, grows back and requires maintenance. Prescribed fire is the best treatment option for this forest type, if possible, after the initial mechanical treatment. While consuming some of the standing vegetation; prescribed fire also eliminates material left on the ground from both mastication and the natural shedding of leaves, needles, etc. Fire is the only natural process used as a treatment method and produces the most effective results for hazardous fuel reduction while enhancing woodland health. Ponderosa pine woodlands are a drought resistant species that have evolved with a natural cycle of frequent, low-intensity fire.
Prescribed fire mimics this natural process and improves forage for wildlife, as well as increasing plant diversity by creating breaks in the understory where grasses and flowers can thrive.
Every year the west is impacted by large catastrophic wildfires. Prescribed fires and other treatment methods lessen the impacts of future fires and increase the likelihood firefighters can work safely and be effective at stopping fires in and near treated areas.
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