Wildfires that tore through more than half a million acres in Southern California have left hundreds of homes vulnerable to mudslides and may have wiped out critical habitat for fast-dwindling species, wildlife and emergency management officials said.
Federal and local authorities are scrambling to stabilize hillsides before winter rain arrives, hoping to prevent landslides and ensure that silt and ash do not further harm reservoirs, watersheds and bottomlands that shelter arroyo toads, songbirds and centuries-old coast live oaks.
"We're pushing up against winter fast," said Todd Ellsworth, a federal soils scientist overseeing teams that fanned out across seven counties last week to assess fire damage and the perils ahead. "Every one of these major burn areas is above homes; they are near many, many homes. Our top priority is to minimize threats to those communities."
Five people died in a massive mudslide in San Bernardino County on Christmas Day in 2003, two months after wildfires ravaged steep slopes above their church camp.
Water quality is also a concern. Destroyed home sites and drifting ash may contain lead, copper or other toxic substances that can leach into creek beds or runoff, killing wildlife and possibly contaminating municipal water supplies, said Ellsworth.
More than 20 small water systems in Los Angeles and San Diego counties whose customers include restaurants, mobile home parks and community centers, are under mandatory orders to boil water because of wildfire damage and subsequent bacterial contamination, said California Department of Public Health spokeswoman Lea Brooks.
San Diego water officials also fear that runoff from burned areas will cascade down the denuded slopes above Hodges, Sutherland and Barrett reservoirs, where fires burned nearly to shorelines. "Keep Out" signs are being posted to try to prevent off-road vehicle users and cyclists from breaking through the crusty soil and creating gullies and ravines.
Although damage assessments are not complete, experts said the increasing rate of wildfires over the last several years has put enormous pressure on wildlife that had already been pushed into smaller habitats by development.
The coastal cactus wren, a large songbird with a chortling call, and two rare species of butterfly appear to have lost their largest known populations in the Witch and Santiago fires. The cactus wren, which hunkers down rather than flying away during blazes, nests in mature, decades-old stands of prickly pear cactus. Many of those cactuses are now melted ruins.
The caterpillar of the Hermes copper butterfly lives in one kind of redberry bush that has been burned or bulldozed for development across much of San Diego County. The Thorne's hairstreak butterfly can survive only on the rare Tecate cypress tree, which needs flame to release its seeds but cannot withstand too-frequent fire. Many of those trees burned in the previous fires in the last five years. San Diego County wildlife staff said they believed some of the butterfly populations had survived last month's fires.
In addition, massive live oaks that had withstood centuries of flame and flood are toppling at an alarming rate in burned areas. Trish Smith, a biologist with the Nature Conservancy, surveyed the skeletal, splayed remains of a once-thriving oak woodland along Santiago Canyon Road in eastern Orange County on Wednesday. "This is bad," she said. "These poor, poor oaks; they were probably 200 years old."
The Santiago fire, which officials say was caused by arson, charred more than 28,000 acres, including 90% of Limestone Canyon, which burned in a 1998 fire. That blaze had left many of the massive old trees with "heart rot" at their base, diminishing their ability to resist subsequent spring floods and severe drought.
"This fire will just exacerbate that," Smith said. "A lot of trees are splitting in two already and falling."
Ecologists said that although Southern California landscapes have evolved to burn and flood, the greater frequency of fires and mudslides caused by humans does not allow the decades necessary for recovery of chaparral and riparian woodlands.
"One of the greatest fire tragedies for nature has been the re-burning of areas lost in 2003 . . . that had only just begun to recover," said David Hogan of the San Diego office of the Center for Biological Diversity. "This may be the last straw for many endangered species that have already suffered so much habitat loss to development and overly frequent fire."
The latest firestorms threaten to undo years of work spent cobbling together nature preserves that protected mam- mal crossings, unique habitat and food sources. Dick Bobertz, executive director of the San Dieguito River Park, said the Witch fire scorched 75% of the park's 80,000-acre greenbelt and destroyed the park headquarters.