On Dangerous Ground : San Gabriel Mountains: Some recreational trails are unsafe in the wake of devastating fires, the Forest Service warns.

The fires that raged across the San Gabriel Mountains in October severely damaged miles of recreational trails, making them unsafe for hikers, bikers and equestrians, the U.S. Forest Service warns.

“There is a dangerous situation out here,” Forest Service official Don Gilliland said as he cautiously ascended the denuded Sam Merrill Trail above Altadena to inspect damage. “There’s bound to be a mishap sooner or later.”

Footing is unsure on the loose, charred earth and the damaged trails are closed to the public. Although some trails may seem passable, hikers, mountain bikers and equestrians alike could easily start a landslide and fall from precipitous slopes, Gilliland said as he looked around the barren landscape dotted with blackened skeletons of trees and bushes. However, no major accidents have been reported in the Angeles National Forest since the fires.

More than 36 miles of trails and about 30 miles of roads were badly damaged by the wildfires that destroyed 5,700 acres in the San Gabriel Mountains.

Crumbling rock, loosened by the fires and given a freer rein than when chaparral covered the slopes, continues to tumble. There is little or nothing to stop rock or mud from cascading long distances, gathering momentum and mass as it goes.

Several weeks ago, a boulder crashed into a county Fire Department truck traveling on the Mt. Wilson Toll Road, a popular recreational route that is now closed. The boulder slammed into the truck’s roof, but no one was injured.

“If that happens to someone on a mountain bike or a horse, they probably wouldn’t fare very well,” said Cam Lockwood, trails coordinator for the forest.

Since the fires, gentle rains combined with a strong windstorm have contributed to the early stages of severe erosion. “The amount of erosion is mind-boggling,” said Reece Vogel, a member of the steering committee of the Mt. Wilson Bicycling Assn., which is among several volunteer groups helping repair trails.

“We’re in a world of hurt,” Gilliland said. “Right now, we have no money for these kinds of repairs. And you can only do so much with volunteers.”

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The Forest Service’s trails repair budget was already strained by damage from heavy rainstorms last January and February. Many repairs arising from those storms were yet to be made before the October fires hit. And other areas that had been repaired from the floods were damaged again by the fires.

Forest Service officials said they can take only stopgap repair measures at this point. Reseeding efforts, controversial in terms of their effectiveness and impact on native plants and animals, are under way in an attempt to stop erosion.

The aim in reseeding and temporary repairs, officials said, is to keep trails from being overwhelmed by rocks and mud that could obliterate the routes.

Permanent repairs will have to wait until after the winter rainy season. Otherwise, said forest Supervisor Michael J. Rogers, “We’d just be pouring money down a rat hole.”

The Angeles National Forest has requested $114,000 in emergency trail and road repair assistance from the Department of Agriculture. But it could be months before Forest Service officials will know the total repair costs.

Likewise, county officials say they don’t know how much it will cost to repair the damaged county trails.

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In the national forest, hard-hit areas include the Idlehour Trail, Idlehour Campground, Castle Canyon Trail, Sam Merrill Trail, Echo Mountain Trail, Sunset Trail, Chaney Sunset Ridge Trail, Winter Creek Trail and Ken Burton Trail.

In addition, the fires seriously damaged the nine-mile-long Mt. Wilson Toll Road, which is maintained by the Los Angeles County Fire Department’s forestry division. Especially popular with mountain bikers, the winding dirt road with its stunning vistas of the Los Angeles Basin is now closed indefinitely with a locked gate.

There was damage to 13 miles of trails in Altadena maintained by the Los Angeles County Parks and Recreation Department.

A crew of 20 county employees and volunteers last week labored along the 10-mile-long Altadena Crest Trail. “Virtually the whole trail has been impacted,” county trails planner Cynthia D’Agosta said. “We’re working hard to keep it open but the outlook isn’t good.”

The affected trails and roads on south-facing slopes of the San Gabriels are officially closed and signs have been posted saying so, although officials acknowledge they have no money to pay for policing the areas.

“You can’t keep them out,” said Gilliland as hikers passed him on the Sam Merrill Trail, which leads from Altadena to Echo Mountain and beyond toward Mt. Lowe.

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He looked up the mountainside to see a man who was hiking off the trail. “People like that are doing us a disservice. They’re accelerating the erosive action.”

Just riding a mountain bike on the trail can make erosion worse in these conditions, Gilliland said. “If they want to ride now, they’ll just tear up and destroy everything. There will be nothing left to ride.”

He looked across the expanse of mountains and pointed to where three small gullies have formed in the last month. “That’s what we’re fighting against.” The mountain air carried the scent of burnt chaparral and, more ominously, a faint sound of small rocks sliding downhill.

A hiker, Carol Larsen, 61, of Altadena passed Gilliland. On her way down the mountain from a morning hike, she said: “You read John McPhee’s book and you know this slope can’t stay through the winter.”

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In his 1989 book “The Control of Nature,” New Yorker magazine writer McPhee detailed the precarious position of Los Angeles County’s foothill communities, built hard against the eroding San Gabriels. He told of the region’s battle to forestall the flows of mud and the torrent of water cascading down the mountains after wildfires strip vegetation from the steep slopes.

Larsen looked toward her house about half a mile away. Presumably, she said, her home of the last 30 years is a safe distance from any mud flows, but she doubted that would be the case for the neighborhood of houses right up against the base of the Sam Merrill Trail, already ringed by a wall of sandbags.

“Without vegetation here, those people are in deep trouble and so are the trails,” Gilliland said.

Still, there is hope, he said, looking down at the blackened stems of a plant by his hiking boots. “You’re standing here in the middle of what looks like the moon but look at the base of that plant,” he said, pointing to tiny sprouts of green. “Nature is trying to heal itself.”

Fire Damage on the Trails

More than 36 miles of recreational trails and about 30 miles of roads were badly damaged by the October wildfires in the San Gabriel Mountains above Pasadena and Altadena.

The affected trails and roads in the Angeles National Forest are officially closed. Even though some of the trails may seem passable, U.S. Forest Service officials say that hikers, mountain bikers and equestrians who traverse these trails are putting themselves at risk because of possible landslides on the denuded slopes.

The damaged areas include the Idlehour Trail, Idlehour Campground, Castle Canyon Trail, Sam Merrill Trail, Echo Mountain Trail, Sunset Trail, Winter Creek Trail, Ken Burton Trail, Altadena Crest Trail, Chaney Sunset Ridge Trail and the Mt. Wilson Toll Road.

Most likely, the trails will not be repaired or reopened until late spring, Forest Service officials said.