Trying to Read the Mind of a Mudslide : Conservation: Malibu struggles with nature. Where might the next deluge be? And what can be done to prevent it?


“I don’t mean to sound flippant, but nothing is a surprise out here.”

So says John Clement, public works director for Malibu. And small wonder: Like most city officials, he has been faced with disaster after disaster of late.

Indeed, the colossal mud and debris flows that were unleashed in Sunday’s storm, the worst one yet, were not unexpected.

“It was just textbook of what happened in the last storm, only worse, and there was only two inches of rain,” Clement said.


City officials said that in this storm, the third to hit Malibu in two weeks, at least 30 houses sustained serious water and mud damage. That figure appears to be climbing, said Sarah Maurice, spokeswoman for Malibu. At least two homes on Pacific Coast Highway had their foundations exposed when huge portions of asphalt collapsed from the weight of the mud and debris.

About 25 houses were damaged in the Feb. 7 storm, with a few getting hit again Sunday.

The city has once again accelerated its efforts to predict the unpredictable. Where might the mud come down next? How much more mud and how many more boulders could still be sitting up in the mountains? And what can be done to prevent it?

What is clear is that the most vulnerable areas have been those where the Nov. 2 firestorm burned away virtually all the vegetation--Las Flores Canyon, Big Rock Drive, Piedra Gorda Canyon and the land along Pacific Coast Highway.

New areas that suffered considerable damage in Sunday’s storm were along Pacific Coast Highway below Pena Canyon and at Serra Retreat on Serra Road, where seven houses were inundated.

The problem has been that the amount of mud that comes down is more than the check dams, debris walls and racks, and catch basins can hold, Clement said.

“The river at Las Flores Creek is now higher than the road from the last rain because it deposited a phenomenal amount of silt and debris,” Clement said. “We are now putting a dam up at the hairpin turn at Big Rock Drive and PCH, and another at Las Flores Canyon and PCH. We can only hold back so much of it.”


Rosann Durrah of the U.S. Department of Agriculture’s Soil Conservation Service toured the stricken areas of Malibu on Monday and Tuesday. The agency was called in after the Nov. 2 firestorm to counsel the city and its residents on how to protect property from mud and debris flows in the denuded hillsides.

“We don’t know how many more boulders and debris are up there,” Durrah said Wednesday. “There are some areas that we can’t even get to. But all the (catch basins and retaining walls) we built in Las Flores Canyon and Carbon Canyon and the culverts worked perfectly in the last storm to stop boulders.”

Clement said the city, using funds from the Federal Emergency Management Agency, will erect dams in Piedra Gorda Canyon above Big Rock Drive, where the most devastating flooding has repeatedly occurred.

To further reduce flooding at Big Rock Drive and Pacific Coast Highway, Clement said, city engineers and geologists will install overflow pipes along Pacific Coast Highway across from Big Rock Drive, where drains at residences have failed to work.

The city also plans to look for long-term solutions. As a first step, it plans to use FEMA funds to conduct a geological study of Piedra Gorda Canyon and the Big Rock area.

According to soil experts, however, Malibu will be vulnerable to mudslides for four to five years--until hillside vegetation grows back.


“What happens next,” said Clement, “is dependent on the mercy of God and the intensity of the next rain.”