Wilderness Fire: Ecosystem Peril Born in Ashes

The aftereffects of the San Gabriel Wilderness Area fire that burned for five days and destroyed 2,400 acres of the popular refuge could cause severe damage to the region’s ecosystem and, in particular, imperil the most important trout streams in Southern California, authorities said Thursday.

U.S. Forest Service officials and conservationists said the unusual intensity of the fire will exacerbate erosion into the West Fork of the San Gabriel River and its tributaries. It is among the few streams in Southern California--and the only one in Los Angeles County--pure enough for trout to breed, conservationists said.

The erosion farther downstream to the San Gabriel Reservoir promises to run up costs in planned cleanup there and could also push up water bills in the East San Gabriel Valley, said Donald F. Nichols, a regional director for the Los Angeles County Public Works Department.

The fire, which started Sunday afternoon when unknown visitors dumped smoldering charcoals by a roadside, has caused $4 million damage to the wilderness and cost $852,000 to fight, according to Forest Service estimates. Battled by 1,400 firefighters, the flames were contained Wednesday and extinguished early Thursday. Forestry officials who had earlier estimated that the fire had burned up to 4,000 acres reduced the figure to 2,400 acres on Thursday.

Remain Open

Flames burned a kidney-shaped pattern along the west fork of the San Gabriel River, jumping Bear Creek and two smaller tributaries. The west fork and Bear Creek are the most heavily used trout fishing streams in Southern California, with about 35,000 visitors a year. Most of the campgrounds and hiking areas remain open, although rangers advise visitors to avoid the Bear Creek Trail.

“The main thing that makes this fire so critical are the three streams flowing within the perimeter of the fire,” Forest Service biologist Steve Loe said. “Soil and sediment has no place to drop off before it gets to the streams.”

Sediment has already been found five-feet high in places, he said.

The sheer intensity of the fire will also have long-range impact on runoff, forest rangers said, because it left a waxy residue that reduces the ground’s absorption. The region had not experienced a fire since 1956, District Ranger Donald Stikkers said.

“The fire burned with great intensity,” he said, “because of all the chaparral and buildup of dead plants over the years.”

The most immediate concern is the impact on the trout spawning season next spring, Loe said.

“If that (sediment) moves down and gets deposited in the gravel of the west fork, it can really reduce spawning. . . . Trout need real clean gravel to reproduce in. If you get silt on top of that gravel, it traps the eggs and the young die,” he said.

Fly fishermen may have to travel far to practice their avocation. In Los Angeles County, “it’s not like there are other places to go,” said Jim Edmondson, a member of CalTrout, a statewide conservation group that specializes in trout habitat.

“This is it,” he said. “Some days there are as many as 150 people on that stream.”

Loe said the west fork has three species of fish: Rainbow trout, speckled dace and arroyo chub.

Edmondson, however, predicted that the ecosystem will rebound fully within a few years, perhaps sooner. A big aid will be detailed information on Bear Creek that was developed during recent efforts to revive the trout habitat of Cogswell Reservoir, which had been severely damaged by extreme siltation. The Cogswell Reservoir is located up Bear Creek and is thus unaffected by runoff from this fire.

A team of forestry specialists went to work Wednesday trying to develop a plan to mitigate the environmental threats, largely through replanting grassland.

Aside from the potential threat to trout and other native fish, the area may be without some of its native wildlife, particularly deer, for “up to 10 years,” Loe said.

Deer are rarely killed by fire, he said, because they are able to run clear of the flames, but they probably will not be able to return to their habitat. After fires, there are usually stands of unburned vegetation that provide cover for animals as burn areas grow back, he said, but this time, “there are hardly any.”

Nichols, the public works official, said as much as 500,000 cubic yards of dirt and debris could run off into the non-recreational San Gabriel Reservoir, trimming about 300 acre feet from its 40,000 acre-foot capacity.

“This could sop up more of your tax dollars” committed to a planned dredging, he said. In addition, the East San Gabriel Valley water districts that siphon water from the reservoir may incur greater costs in treating their drinking water, he said.

With an average of 4 million visitors a year, according to forestry officials, the San Gabriel Wilderness Area is busier than the busiest national park, Yosemite. Thousands of campers and hikers were evacuated from the wilderness area on Sunday.