Firefighters moved closer Wednesday to fully containing the 33,424-acre Apple Fire, which U.S. Forest Service officials said will have inevitable impacts well after it’s fully extinguished, including compromised soil that will increase flash flood risks.
According to the USFS, flooding and debris flows that could damage homes and other structures are a significant threat in some locations ringing the burn scar.
The agency released a statement urging “residents and visitors (to) remain alert to weather events and plan ahead when traveling along roads and trails within and downstream from the burned areas on the San Bernardino National Forest.”
The USFS is already standing by to “assist affected businesses, homeowners and landowners in preparing for rain events” as the summer monsoon season reaches its apex, and as the winter rainy season approaches, according to the statement.
In its advisory, the Forest Service encouraged residents in Riverside and San Bernardino counties who are in the vicinity of charred spaces to pay close attention to National Weather Service alerts, as well as county evacuation warnings and mandates.
“Prepare for rainstorms by being prepared to evacuate if county or city emergency officials determine that flooding and mudflows are expected which could pose an increased threat to human life, safety and property,” the agency stated. “Practice evacuations prior to real events. Understand that all drainages within and downstream of the burned areas can produce flooding.”
High-intensity thunderstorm cells fueled by monsoonal moisture developed over the San Bernardino National Forest early Tuesday afternoon and trackedto the north, looking as though they would stall over the portion of the burn scar close to Forest Falls. However, the cells veered sharply to the northwest, with most of the energy shifting away from the fire zone.
The USFS released a burn severity map Tuesday highlighting the corrosive impacts of the nearly three-week Apple Fire, and according to the assessment, 75% of the burn area sustained moderate to severe soil damage.
“The (USFS) team expects erosion and run-off within the Apple Fire area to increase as a result of the fire because 75% of the burned area experienced moderate or high soil burn severity,” agency spokesman Todd Ellsworth said.
He said the greater the burn severity, the higher the likelihood of heavy water and debris flows from slopes, threatening roads and communities below.
The map indicated run-off threats to Cherry Valley, the Morongo Indian Reservation and neighboring locations in both Riverside and San Bernardino counties.
Since sparking July 31 in Cherry Valley because of burning exhaust from a diesel vehicle, the Apple Fire, now 95% contained, has injured four firefighters and destroyed four homes and eight outbuildings. An estimated 2,600 residences and 7,800 people were evacuated at the height of the blaze, which has cost $51.8 million to confront.
Roughly 250 fire personnel remain assigned to the blaze, tightening containment lines, aided by five water-dropping helicopters, according to the USFS.
The brusher burned through federal, state and private lands, according to Cathleen Thompson of the U.S. Department of Agriculture, and several governmental agencies will have to conduct their own post-fire assessments, as the Forest Service has already done, she said.
The San Gorgonio Wilderness area — where 7,249 acres have burned — remains closed to the public.
A portion of the Pacific Crest National Scenic Trail is closed to all traffic between the Cottonwood Trailhead, near the community of San Gorgonio, and Forest Road 1N01.
All recreation areas in the Forest Falls area are inaccessible, as well.
Additional information about the closures can be found at www.fs.usda.gov/sbnf.