USA — When cold, wet weather moved into Southwest Idaho early last week and abruptly turned summer into fall, it put out the last flames of the 4,671-acre Castro Fire in the Boise National Forest.
The blaze had been active since Aug. 4 with the blessing of Boise National Forest officials.
The Castro Fire burned for two months at a low to moderate intensity in the forest north of Lowman, with some limited but targeted work from firefighters to make sure the blaze didnt blow up or move into areas considered more at-risk. The fire was put out the old-fashioned way by weather.
It was cool, wet weather in the spring that gave Boise National Forest officials the flexibility to allow the Castro Fire to burn.
Since 2004, Boise National Forest policy has allowed land managers to let some wildfires burn in an approximately 500,000-acre portion of the 2.6-million-acre forest if certain conditions are met to help return the overgrown woods to health.
In fact, Boise forest fire officials would have liked to use that approach more this year, but weather did not cooperate. Of the six fires ignited by storms being considered for resource management this summer, five went out on their own before burning any significant acreage. The only fire that remained active was the Castro Fire.
Those conditions of the summer of 2011 rarely existed in the early 2000s, thanks to long-term drought in Southwest Idaho. Wetter springs over the past several years have allowed forest managers more flexibility if they get fires that start in the right place at the right time.
These kinds of wet years really allow us the ability to reduce the fuel that is out there, Boise National Forest spokesman Dave Olson said. If we dont do it now, that same fire could turn into a high-intensity (tree) stand- replacing fire in a drier year.
With cooler spring and early summer temperatures, we can take advantage of fire playing its natural ecological role, Boise Forest Supervisor Cecilia Seesholtz said. We hope to use these smaller and more manageable fires to prevent the large and intense fires that became all too common in the past.
Most of the wildfires in 2011 in the Boise area comprising about 9.1 million acres, including the Boise National Forest and Boise District of the Bureau Of Land Management were range fires in the desert.
Of the 158,014 acres burned by wildfire in 2011, only 4,766 acres burned in the Boise National Forest. That number includes the 4,671-acre Castro Fire. By contrast, 153,069 acres burned on BLM rangelands this summer.
Still, the Castro Fire was the third-largest natural burn area since the program began in 2003. Conditions werent good enough to even try the program until 2006. Since then, Boise National Forest officials have used this approach to manage 17 wildfires that have burned a total of about 35,000 acres.
In the case of the Castro Fire, firefighters managed the growth in a few different ways.
On Aug. 26, high temperatures and wind resulted in fire activity that could have pushed the Castro Fire north towards the Bull Trout Lake campground, so fire crews set a burnout fire at one area and used a helicopter to cool other parts of the fire with water drops.
A few days later, when it looked like the Castro fire might move south towards Idaho 21, three hot shot crews were deployed to cut down some trees, construct minimal fire lines and get some hose lines down to work on hot spots.
Fire officials also provided regular updates to residents of Lowman on the status of the fire and set up a smoke monitor in town. Some popular recreation trails had to be closed.
By the time rain put out the Castro Fire last week, it was centered between areas recently burned by the 8 Mile Fire in 2009 and the Red Mountain Fire of 2006, creating a series of fire breaks in the area.
Allowing those fires to burn helped clear out dense and overgrown stands of lodgepole pines and subalpine firs that fill that area.
The practice helps return nutrients to the soil and create a natural mosaic pattern of new and old growth, which creates natural fire breaks and helps keep future wildfires from growing into catastrophic blazes.
At least a few areas of the Castro Fire included areas of bug-killed trees, which can really add to the intensity of wildfires during hot and dry conditions. Since the Castro Fire burned at low to moderate conditions, that didnt happen, Olson said.
The practice of allowing some resource-benefit wildfires to burn is part of a slowly evolving nationwide effort to restore a natural balance to forests where fires have historically kept undergrowth in check and helped maintain long-term forest health.