Mudslide Threat Prompts Call for Task Force Study

With the rainy season approaching, Los Angeles County Supervisor Zev Yaroslavsky called Friday for the creation of a task force working to prevent mudslides that often follow severe fires in mountain and canyon areas.

“When there are fires, we actually have two disasters: the fire and the aftermath,” said Yaroslavsky. “We have spent a lot of time on mitigation of fires, now we have to address the second part.”

After last month’s wind-whipped Calabasas-Malibu wildfire burned more than 13,000 acres in the canyon areas between the San Fernando Valley and the Pacific Ocean, a rainstorm dropped as much as 6.5 inches on the area, causing some erosion on the denuded hillsides.

“The soil here is very loose,” said Calabasas City Manager Charles Cate. “It doesn’t take much for it to come down like soup.”

The proposed task force would be charged with seeking ways to control erosion on charred hillsides in the Santa Monica Mountains. The group will probably tackle the thorny question of what type of vegetation should be planted--native plant seed or quick-growing rye grass.

Conservationists complain that fast-growing rye grass crowds out the natural flora and does little to prevent erosion. State forestry officials, who have planted rye grass in parts of Altadena, Thousand Oaks and Laguna Beach, say they also prefer native grasses but they are hard to find.

Membership on the task force would include the U.S. Forest Service, the state Department of Transportation and the cities of Calabasas and Malibu. Environmental groups will also be represented. The Board of Supervisors will decide whether to create the Post-Fire Watershed Recovery Task Force at Tuesday’s meeting.

In rains following the 1993 wildfires in the same area, water runoff created mudslides on the bare hills in Los Angeles, damaging homes and closing roads.

County officials have said that the rainstorm that doused the burned area last month loosened boulders that in future storms could tumble onto Malibu Canyon Road, one of the few north-south links in the area. Another key link, Kanan Dume Road, has been closed since September due to erosion under the asphalt.

To prevent further mudslides and erosion, crews from the county Department of Public Works are diverting the hillside streams created by water runoff.

“We are out there now trying to create something to retard the potential flows of waters by causing them to zigzag,” said Yaroslavsky. “We think we can protect public roads and bridges that way. But long term, we need to look at erosion control measures in an environmentally sensitive way.”