Drainage systems also need to be cleared along an 8-mile stretch of the highway about 80 miles north of downtown Los Angeles, said Florene Trainor, a spokeswoman for the California Department of Transportation. Officials hope to reopen the highway by Thursday.
Geologists determined that nearby hillsides were stable, so there were no fears of another mudslide if it starts raining again, Caltrans officials said. The area got some weekend drizzle, but no serious rain, and a dry period was developing, forecasters said.
County Supervisor Mike Antonovich is expected to ask the Board of Supervisors to declare a local state of emergency Tuesday in response to recent storms in the Antelope Valley, reports CBS Los Angeles. If approved, the declaration will free up state resources to help with cleanup and recovery.
To the south, Los Angeles County crews reopened stretches of five roads in mountain communities about 40 miles north of Los Angeles that also were inundated during the flooding.
The reopening Sunday came well ahead of original forecasts, with more than 40 bulldozers, dump trucks and other heavy equipment working through the weekend to shift an estimated 200,000 cubic yards of mud, according to a Los Angeles County Public Works statement. Work continued on two other roads in the Lake Hughes and Lake Elizabeth areas.
Nearly 3 inches of rain fell in 30 minutes Thursday in the Leona Valley area of Los Angeles County. Hundreds of cars got stuck on Interstate 5.
Homeowners in northern Los Angeles County communities spent their weekend digging mud out of their houses.
At least one of the homes is considered a total loss after flooding ripped it from its foundation, Kerjon Lee, a spokesman for county Public Works, said. Crews were assessing homes in the area, and Lee said the number of those destroyed could rise.
Carrie Bowen, a district director at the California Department of Transportation, said the agency is reviewing storm response to see if Caltrans could have done anything better, a standard procedure following major events.
But "it was a flash flood that happened so quickly - 4 to 6 inches of rain in a short period of time," Bowen said, adding that the agency alerted drivers as best it could and worked with other agencies to divert traffic from affected roadways.
"I don't know that we could have (done better) given the volume of mud," she said.
At a news conference Monday, Bowen and other state officials urged Californians to be prepared for an unusually wet winter and the potential for more flooding because of the El Nino phenomenon that experts say has formed in the Pacific Ocean.
Most of the storms California has been seeing are small, intense cells, while El Nino is likely to bring more widespread events, said Bill Croyle, deputy director of statewide emergency preparedness and security for the California Department of Water Resources.
"Mud and debris flows will be an issue," he said. "Those are the things that we're going to have to stay on top of."
Authorities urged residents to maintain survival kits, identify evacuation routes, clear debris from gutters and storms drains, follow instructions from emergency officials, and stay home when dangerous weather is expected.
They also acknowledged there's only so much anyone can do during severe weather events.
"There's going to be situations where (a weather event) is just going to be there, and there's no right answer for what to do when you're in the middle of it," said Chief Scott Edson, who heads the special operations division of the Los Angeles County Sheriff's Office.
Last week's rain struck some remote areas. "If that happens, you're kind of stuck until someone comes to get you," Coyle said.