How Hazardous is Larimer County?
A recent study ranked Larimer County as the most hazardous County in Colorado for wildfire hazards. An earlier report ranked Larimer County second. Both studies indicate the potential of wildfire to burn structures and threaten lives in the County is high and will only continue to grow as more and more people move to the mountains.
Night shift on a 300 acre fire near Drake, CO 1993.
A survey completed in 1995 by the Colorado State Forest Service estimates that 57% of subdivisions and other development in western Larimer County have a high fire loss potential. Fire loss potential combines the potential to burn (hazard) with the potential for ignition and the average fire size to estimate the likelihood of a devastating wildfire occurring in a community.
On average, over the past twenty years or so, 161 wildfires burn over 2200 acres each year in Larimer County. In "slow" years, such as 1996, wildfires are relatively small and, though many homes may be threatened, no homes burn. At the other extreme is a year like 1994 when 340 fires, including the Hourglass Fire which destroyed 13 buildings at Pingree Park, burned through Larimer County. From 1985 to 1996 fires burned a low of 156 acres in 1992 to over 11,000 acres in 1988. Historical records show that, 2% of all wildfires reach 100 acres or more in size. Must we wait until disaster strikes before something is done?
Using historical data, we can expect 20 fires greater than 100 acres in size to occur on state and private lands within Larimer County during the next ten years. Exactly when and where these fires will occur is anyone's guess.
Disastrous wildfires are not uncommon along Colorado's Front Range. A wildfire in 1950 in El Paso County killed nine firefighters and destroyed 33 homes. The Murphy Gulch Fire threatened six homes in Jefferson County in 1978. In 1989 the Black Tiger Fire demolished 44 homes and threatened at least 100 more in the Sugarloaf area of Boulder County. Tragedy again struck Boulder County in 1990 when 10 homes were destroyed just north of the city of Boulder. Numerous wildfires threatened structures up and down the Front Range in 1994. In May of 1996, 12 homes burned in the Buffalo Creek Fire southwest of Denver.
"Our foothills and canyons are a beautiful and often perilous place to live. Many people who chose to do so take prudent steps to protect their property. Others, as officials working the Sugarloaf fire pointed out, have not done so, making efforts to save their homes virtually futile."
Fortunately, major residential home loss from wildfire has not occurred yet in Larimer County. However, wildfires now threaten structures every year. In addition to destroying 13 buildings at Pingree Park, the Hourglass Fire threatened 12 homes in the Poudre Springs area. The Snowtop Fire, in July 1993, threatened at least 5 homes in Cedar Park. In 1995, a relatively wet year, the Bonner Peaks Fire threatened 8 homes west of Highway 287. During the summer of 1996, several fires ranging in size from one acre to 180 acres, threatened 50 to 60 homes throughout Larimer County.
"Please do not wait to act...until after the inevitable calamity."
As so many fire ecologists, firefighters and others have said, the question is no longer if a major wildfire is likely to occur, but when and where will the fire burn.
Wildfire, along with climate and topography, plays a major role in determining the structure and composition of Rocky Mountain forests. Fire frequency and severity are critical in determining which plant species grow on a particular site. For this reason, species such as aspen may be favored by shorter fire frequencies, but lost from sites during unusually long fire-free periods. Very short fire frequencies may result in the loss of conifer species unable to establish a seed pool.
Remains of a structure following the wildfires of 1994 in Larimer County
Wildfire has returned to our forested ecosystems at fairly frequent and somewhat predictable intervals, with estimates of the historical fire frequency varying with forest type. Fire frequency of ponderosa pine in Rocky Mountain National Park has been estimated at 30 years, while other studies indicate fire frequency ranging from 12 to 46 years in ponderosa pine along Colorado's Front Range. Fires in Rocky Mountain National Park lodgepole forests have been estimated to occur every 50 years. Evidence indicates the lodgepole forest in the Pingree Park area burned about 120 years ago.
Historically, the occurrence of lodgepole pine is largely controlled by fire frequency and severity. Lodgepole seeds in recent burns to form dense, "dog-hair" stands that often remain until destroyed by another wildfire. When homes are built in lodgepole pine forests, the results can be disastrous.
How much wildfire changes forest structure and species composition depends on current forest conditions, weather, topography and fire intensity. Many decades of fire suppression have significantly altered the historical fire regimes in Larimer County. Years of fuel accumulation caused by successful fire suppression, lack of forest management, a general public misunderstanding of forestry and fire ecology, and the increasing number of homes and communities in our forests, have created a significant wildfire problem. Each year that passes without addressing wildland fuels buildup simply increases the potential for disaster.
Wildfire is defined as any fire occurring on wildlands that requires suppression response. If left unchecked, it is likely these fires will threaten lives and property.
Wildfire behavior and spread are affected by fuels, topography and weather. Fuels, typically thought of as grass, brush, trees, and dead vegetation, now include homes and other structures. Ironically, improved fire protection combined with decreased forest management has contributed to increased fuels.
Topography helps determine fire spread. Because heat rises, fire spread increases as slopes become steeper. Homes built in canyons or on ridge tops frequently have less chance of surviving wildfire. Steeper slopes also hamper suppression efforts. Historically, fire occurrence is greater on south and southwest-facing slopes due to lower amounts of fuel, higher temperatures, lower humidity, and lower fuel moisture.
Weather, the most critical and the most unpredictable element of fire behavior, is constantly changing and often determines fire size. Hot, dry, windy days create favorable conditions for wildfire. In Colorado these conditions can occur anytime throughout the year. Most large fires are wind-driven events.
Wildfire cannot be eliminated from forested ecosystems. In fact, the incidence of catastrophic wildfire appears to be on the rise in Colorado!
Where hazardous fuels, difficult terrain, and extreme weather exist, all that is needed for a wildfire to occur is an ignition source.
Lightning strikes the earth an average of 100 times each second, totaling over 3 billion strikes each year. Though lightning is typically responsible for 30-45% of all fires on federal lands in Larimer County, only 11% of all wildfires on state and private land are lightning-caused. The remaining 89% are human-caused or are of unknown origin.
Reviewing past wildland/urban interface fires shows that structures are destroyed or damaged by wildfire for the following reasons:
The wildfire safety recommendations provided by Larimer County's Wildfire Safety Task Force are an attempt to establish a reasonable set of standards and guidelines to minimize the loss of life and property from wildfire.