Even as firefighters contain the Southern California wildfires, officials are scrambling to combat another looming natural disaster in the smoldering hills: mudslides.

Authorities are racing to stabilize denuded slopes before they are washed away by winter rain, sending what could be devastating floods and mudslides into communities built on what were once barren alluvial plains.

"If people think fire is bad, mudslides could be even worse," said U.S. Forest Service (search) spokesman Matt Mathes. "This is probably going to be the single largest effort to rehabilitate fire-burned land in history."

The weather that helped drive and then quell the fires is so volatile this time of year that officials fear they may have until Friday before the first potential storm of the year.

"There's enormous urgency to get rolling," said the Forest Service's Jack Blackwell, who oversees California's national forests. "It's going to be an enormous job."

Even as the fires raged, teams of botanists, biologists, engineers, archeologists and watershed specialists were moving in behind the fire crews. They assessed the damage done by bulldozed and hand-cut firelines and helipads, scars that can be more harmful than fire itself to an environment that has tolerated periodic blazes for eons.

In their wake come the BAER — Burned Area Emergency Rehabilitation (search) — teams that are trying to predict, and if possible prevent, mudslides. A mudslide blanketed Highway 18 near Crestline over the weekend, slowing emergency crews racing to fires in the San Bernardino Mountains (search) and the return of residents to burned-through areas near Lake Arrowhead.

"This is by far unprecedented as far as the complexity and the number of folks and the amount of acreage," said Rob Griffith, who expects to allocate tens of millions of dollars as coordinator of the Southern California response.

Federal, state and local teams have been assigned to four units, for the San Bernardino area, the San Diego area, the Ventura County area, and the Los Angeles County area. The wildfires swept across more than 743,000 acres and destroyed more than 3,500 homes.

"Because it's such a big fire and we have such a short window, we're trying to hit the highest of priorities first, and then work our way down the list," said Todd Ellsworth, who heads the BAER teams assigned to the Old and Grand Prix fires in the San Bernardino National Forest. "Everything's important. It's just that some things are more critically important, and we're running out of time."

That means protecting life and property. Archaeological sites and wildlife habitat, both of which have survived fires before, are farther down the list.

That's in part because while most western wildfires burn through remote areas, the Southern California fires seared through and around subdivisions and mountain communities that now are especially vulnerable.

The first effort is to keep water and soil on the hillsides with straw mulch or berms, or at least channeled into waterways with sandbags, fallen trees or other barriers.

"This is Southern California, and it will happen," said Bernie Weingardt, the Forest Service's deputy California forester for resources. "It's just a matter of us being able to predict it, minimize it, direct it, and minimize or prevent loss of life."

The teams are developing formulas for "trigger points" that may signal how much rain the fire-charred slopes can absorb before the water — or the soil itself — starts to run. When the trigger points are reached, authorities issue flash flood warnings and activate the emergency broadcast system, as they did Friday when they feared flash flooding from the Piru Fire in Ventura County.

Southern California's soil itself is less stable than, say, the granite-anchored slopes of the Sierra Nevada, said Andrea Tuttle, director of the California Department of Forestry and Fire Protection.

Resins in the burned vegetation melt into the soil, forming a waxy layer that impedes water absorption, she said.

"Southern California is known for the fire-flood cycle, so it's something we've dealt with before," Tuttle said.