THE DELUGE : Unrelenting Storm Saves Its Worst for Areas in Mountains : Rain: Creeks swell in Calabasas, homes are inundated at Lake Malibu. “I lost everything in there,” says a resident.

Soaked hillsides and bloated creeks and basins in the San Fernando Valley and neighboring areas began succumbing to continuing rains Wednesday, causing mud- and rockslides, flooded intersections, road closures and scattered evacuations.

Wednesday’s storm was particularly devastating to portions of the Santa Monica Mountains at the western edge of the Valley, an area that was saturated with up to eight inches of rain on Monday.

In Calabasas, 81-year-old Bernie Thompson was rescued by neighbors when his car was swept off Crater Camp Road by a cascade of storm water. Plucked from Cold Canyon Creek by neighbors Daryl Lev and Randy Davies, Thompson was taken by Los Angeles County firefighters to Westlake Regional Medical Center for observation.

Five miles upstream, a dozen homes were inundated by a 12-foot flood at Malibu Lake, a community in the mountains south of Agoura Hills. Several houses were covered to their eaves by muddy water.

“I lost everything in there,” said William Swearinger, as he stood on high ground behind his small, lakefront house and watched water lapping inside its windows.

“Furniture, TV, clothes, they’re all gone.”

The rains also did serious damage in west Lancaster and the adjacent, unincorporated community of Quartz Hill, where scores of streets were submerged in mud and water and traffic came to a standstill.

For about three hours, residents were urged to evacuate homes in the area voluntarily, as deep, fast-moving water washed away walls and yards and began lapping at their doors. The flooding brought renewed complaints from Quartz Hills residents that the earth grading at recently constructed housing developments in nearby Palmdale had created a flood hazard.

“I’ve lived here 11 years and we’ve had rain harder than this and we never had this problem till they got that damn development,” said Charles Mizzigili, 42, whose concrete wall with a decorative, wrought-iron top was partially washed away in the storm.

Neighbor Jim Jones, 53, who recently spent more than $10,000 to repair water damage from a storm last year, watched in anger as Wednesday’s floods washed away the large railroad ties he had hauled to his yard for landscaping.

“If it gets much worse, we’re done for,” Jones said. “We were told it would never happen again.”

“I’ve been up here 20 years and I’ve never seen water like this. I’ve seen it rain harder than this rain, but I’ve never seen it flood like this,” Sheriff’s Sgt. Bob Denham said.

Lancaster officials attributed the worst of the flooding to the partial collapse of a large, recently built water-retention basin that gave way in the early afternoon. The problem peaked about 3:45 p.m., when the 300-by-300-by-6-foot basin breached, spilling 10 million to 20 million gallons of water down a hillside and toward the town, city officials said.

In Santa Clarita, a trailer park was briefly evacuated after a swelling creek broke through a block wall, knocking several mobile homes from their foundations and damaging about 20 more. About 20 residents of the 109-unit Mulberry Mobile Home Park were rescued by emergency crews, some by boat.

“I’m cold. I’m homeless. My cars are gone,” said Lori Lewis, 24, who was combing her hair in the bathroom when the torrent knocked her trailer from its foundation and sent her two cars floating away. One car, a 1986 Corvette, came to rest beneath the trailer; the other lodged against a neighbor’s.

Houses in Topanga Canyon remained without electricity for most of the day, and Old Topanga Canyon Road was closed after a mudslide blocked both lanes.

Mudslides also closed portions of the Golden State Freeway near Castaic, and California 126 west of Santa Clarita.

On the Ventura Freeway at the Calabasas Parkway, water undermined a concrete block retaining wall behind a Calabasas Road shopping center, causing it to topple near the eastbound side of the freeway and prompting officials to close two lanes about 10 a.m. No one was injured.

More than 50 horses were evacuated from DaMoor Farms, located in a scenic canyon below Rinaldi Street in Granada Hills. The animals were removed as a precaution after the picturesque features of the site--steep, grassy hillsides on each side and a normally gentle stream--turned into a double threat during Wednesday’s heavy rains.

Stable employees removed the horses--some of them hunter-jumpers worth $100,000 each--so they could be trucked to the Los Angeles Equestrian Center in Burbank.

In Van Nuys, the Sepulveda Dam Basin--where dozens of stranded motorists had to be rescued Monday--filled anew but only to about 20% of its 17,400-acre-foot capacity, said an official with the U.S. Army Corps of Engineers. On Monday, the basin filled to about 55% of capacity.

Lt. Col. Kenneth Steele of the Corps of Engineers assured a state Senate disaster committee touring the area that the dam would be able to withstand oncoming storms.

“There’s no threat in terms of the Sepulveda Dam capacity?” asked state Sen. Charles Calderon (D-Whittier), referring to weather predictions.

“There’s no threat to the capacity of the structure,” Steele replied.

Woodland Hills had 3.61 inches of rain between Tuesday and Wednesday afternoons, and Northridge 4.24 inches, according to the National Weather Service, which forecast intermittent showers today and Friday.

Heavy rains are expected again on Saturday, prompting many residents to prepare themselves by building sandbag dikes.

At Lobo Canyon, which connects with Triunfo Canyon near Kanan Road in the Santa Monica Mountains, residents began repairing flood damage as soon as the storm blew over and Lobo Creek started to recede.

“We were prepared. We diked the house, took down all the fences to prevent debris from collecting and causing flooding, and got our backhoes ready,” said slicker-clad John Staible, an actor.

“We take the bottom board off horse corral fences. If you don’t, they’ll wash away.”

Pam Cavanah, one of 300 residents of the canyon, said Lobo Creek is bone-dry most of the year.

“There’s a week of brush fires out here every few years, and a week of floods,” said Cavanah, who raises 20 horses on a three-acre ranch.

“The rest of the time, it’s gorgeous.”

Times staff writers John Chandler, Richard Colvin, Paul Lieberman and Amy Pyle contributed to this story.

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