‘Prescription for Disaster’ : Buildup of Dry, Dead Brush Has Officials Fearing Wildfires on Hillsides Ringing the Valley

Donald A. Pierpont sees more than natural beauty when he looks up into the mountains that rim the San Fernando Valley.

The Los Angeles County fire captain sees what he calls “the prescription for disaster.”

It is the gray color of brush he sees that bothers Pierpont the most. Spreading amid the brown-and-green vegetation is the ever-increasing amount of gray--dead vegetation that he said could help fuel a fire as disastrous as the one that ravaged the Oakland-Berkeley area last week.

“I see a lot more gray out there than in recent years,” said Pierpont, the department’s vegetation management coordinator. “We have dramatically increased the amount of dead material out there.”

Pierpont and other fire experts who monitor the hillsides of the San Fernando and Santa Clarita valleys say that as the region goes into what is usually the last month or so of the traditional wildfire season, the rules are different. Years of drought have combined with other conditions to make the potential hazard acute. So much so, in fact, that fire officials no longer describe the threat as seasonal.

“Normally, toward the end of November and into December, we would be able to relax,” said Robert J. MacMillan, a Valley-based battalion chief with the Los Angeles Fire Department. “We can’t do that anymore. Because of the drought, we are almost into a year-round wildfire hazard season.”

What’s more, the continued spread of development into wild lands has placed houses closer and closer to the volatile fuel in the hills.

MacMillan, his department’s vegetation management coordinator, said the drought, coupled with die-back, a fungus that has been killing mountain vegetation for more than six years in this area, has created a tremendous buildup of dead material on most mountain slopes.

That buildup could help a wildfire move faster and hotter than a blaze through live brush, he said. Though unusually mild weather during the summer and spring rains may have helped to keep the wildfire danger down, they may also have served to mask it.

“We have the potential, due to the age of the fuel and the condition of the fuel, to have a fire like the one in Oakland,” MacMillan said. “I think people have been swept into a false sense of security because of the unusual weather.”

Officials said it is difficult to pinpoint areas in the two valleys that would be the most hazardous in the event of a wildfire because the risk is throughout the region. But by mapping the paths of previous fires, regularly measuring moisture in live vegetation and monitoring the buildup of dead material, fire experts can chart the probable path and intensity of future wildfires.

The county takes biweekly moisture measurements from live brush at 18 locations in the county. The samples have been taken from the same spots for 12 years, giving fire experts a lengthy overview that allows them to determine when moisture in the brush drops to critical levels, said Keith Deagon, a forester with the county Fire Department.

Currently, Deagon said, the moisture level remains slightly above the critical point, which is reached when the moisture content in heavy brush drops below 60% of the plant’s capacity to hold water. The most recent readings range from a 66% moisture reading in Malibu to a 69% measurement in Castaic.

Deagon said 60% is considered the critical mark because, historically, major wildfires in the county have occurred when moisture levels dropped below that point.

“That level is like a warning,” Deagon said. “It’s kind of like, ‘Time to gear up.’ If there is a fire at that level and you have winds, you are going to have a critical fire.”

Deagon said moisture levels have been dropping steadily, but the pace is slowing and should reverse through the winter.

This weekend’s rains provide only a temporary respite from the danger of fire, county Fire Department Battalion Chief Richard Land said. Land said the precipitation did not affect the dead brush that would fuel a fire, other than to coat it with a sheen of surface moisture that will quickly dry out.

MacMillan said vegetation moisture content is considered the most important factor in the flammability of brush. He said the southern slopes of hills are at the greatest fire risk because they receive more direct sunlight through the year and therefore are drier.

By tracking the paths of fires going back for decades, fire officials can determine what areas have gone longest without fires and therefore have the largest buildup of dead vegetation. These areas can then be attacked by brush-clearing camp crews or cleared with prescribed burns in which the brush is purposely set ablaze by the fire department under controlled conditions.

This winter, the county plans to burn more than 7,000 acres of brush, almost all of them in and around the San Fernando and Santa Clarita valleys. Most of these areas have not burned naturally in more than 30 years, leaving “fuel beds” that could create devastating fires if flames moved into nearby developed areas, Pierpont said.

Among the sites scheduled for prescription burns is a 2,600-acre parcel between San Francisquito and Tapia canyons in Castaic. A fire in the area just north of the Peter J. Pitchess Honor Rancho jail could imperil thousands of inmates, who would be difficult to evacuate quickly, Pierpont said.

Also to be burned will be two parcels close to development, 1,000 acres in Saugus and 300 acres in Newhall.

About 2,500 acres in Potrero Canyon west of Santa Clarita are scheduled to be burned, and in the San Fernando Valley, about 200 acres will be burned in Topanga Canyon.

Prescription burning is too risky in small areas that border on development. Therefore, fire officials said, they also have an aggressive program to keep dead brush clear from what is called the “wild land-urban interface”--the line where neighborhoods push up against and, increasingly, into the hillsides and brushlands.

Pierpont said the lesson of the Oakland fire is that once a blaze crosses the interface, factors such as wind, wood shingle roofs and drought-stressed ornamental vegetation can continue to carry fire for blocks, if not miles, into a residential community.

To combat this threat, fire departments frequently patrol the interface on ground and by air and warn homeowners when they need to clear brush from their properties. About 45 camp crews of adult inmates and juvenile wards of the courts are also used to clear brush and fire breaks in the hills countywide when they are not being used to actually fight fires.

It is a never-ending task, Pierpont said. The interface is never clearly defined because of the ongoing tide of development encroaching on wild lands. And, he said, brush that is cleared away today will be a problem again in the future.

The problem, Pierpont and others said, is that efforts to guard against disasters like the one in Oakland are, in effect, efforts to control the natural renewal of vegetation on the hillsides by fire and regrowth.

“The problem we have is that fire is a natural part of the ecosystem here,” Pierpont said. “Long before we got here, there were fires. And now we’ve come along and done such an excellent job of suppression that we have fuel beds throughout Southern California that have really, really old material. It’s the prescription for disaster.”