Fourmile Canyon Fire Findings

The Fourmile Canyon Fire burned in the fall of 2010 in the Rocky Mountain Front Range adjacent to Boulder, Colorado. The fire occurred in steep, rugged terrain, primarily on privately owned mixed ponderosa pine and Douglas-fir forests. The fire started on September 6 when the humidity of the air was very dry (≈ <7%) and the winds were steadily blowing in the range of 15 miles per hour and gusting to over 40 miles per hour. These conditions prevailed for most of the first day when the fire burned approximately 5,700 acres and destroyed 162 homes. Because of the windy conditions, aircraft could not be used until late that first day. The first responders concentrated on evacuating the occupants of the 474 homes in the fire vicinity. No public or firefighters were injured during the course of the fire. This outcome was directly related to the excellent preparedness of Boulder County and, in particular, the Sheriff's Department and the local fire districts. Fuel treatments had previously been applied to several areas within the fire perimeter to modify fire behavior and/or burn severity if a wildfire was to occur. However, the fuel treatments had minimal impact in affecting how the fire burned or the damage it caused. After the initial day of intense burning and 4 additional days of relatively benign fire behavior, the Fourmile Canyon Fire had burned 6,181 acres and become one of the most damaging fires in Colorado's history. This report summarizes how the fire burned, the damage it caused, and offers insights to help the residents and first responders prepare for the next wildfire that will burn on the Colorado Front Range.