(Recasts with evacuation orders lifted)
LOS ANGELES, March 22 (Reuters) - Authorities in Southern California lifted evacuation orders on Thursday for more than 60,000 people living adjacent to fire-scarred foothills and mountain slopes along the Santa Barbara coast as rains and the threat of dangerous mudslides abated.
The evacuation was put into effect on Tuesday in the same general area where torrential rains in January unleashed cascades of mud, boulders and other debris that killed 21 people, injured dozens of others and damaged or destroyed hundreds of homes.
Most of that devastation occurred in the affluent hillside community of Montecito, 85 miles (137 km) northwest of Los Angeles, in a region where vast swaths of the coastal landscape were stripped of vegetation by huge wildfires in December.
In the aftermath of that disaster, authorities instituted a policy of enforced evacuations in slide-prone areas of Santa Barbara and Ventura counties whenever forecasts call for downpours that might exceed the capacity of the region's catchment and drainage systems to control flash floods.
The latest Pacific storm, the third in two weeks, had been expected to drench local mountainsides with up to 10 inches (25 cm) of rain, and some street flooding occurred in Montecito, said Amber Anderson, a spokeswoman for the unified incident command.
By late Thursday, showers had subsided with no severe mudslides or debris flows reported, officials said.
"We haven't had any significant problems and the bulk of the rain has passed through the area, so there doesn't appear to be any significant threat," Ventura County sheriff's spokesman Sergeant Eric Buschow told Reuters.
A Santa Barbara County Sheriff's Office notice said minor debris flows were still possible "but will not threaten populated areas."
All evacuation orders were lifted as of 5 p.m., Buschow said. But the showers were not without consequences.
In northern California, heavy rains caused a small dam on the Moccasin Reservoir, east of San Francisco, to overflow, prompting the National Weather Service to warn that the structure was in danger of imminent collapse.
Local authorities evacuated areas below the dam, including a campground, a fish hatchery and a marina, and said that even if the dam failed, its water would flow harmlessly downstream into the much larger Don Pedro Reservoir, the sixth-largest in the state.
Several roadways in coastal counties northwest of Los Angeles were flooded, and there have been a number of car crashes on slick roadways, though no deaths, California Highway Patrol spokesman Danny Maher said.
As rains soaked parts of California, the East Coast was digging out from the fourth major snowstorm this month, which closed schools, grounded flights and halted bus and train service across the region. Two people died in separate traffic crashes, local media reported. (Additional reporting by Brendan O'Brien in Milwaukee; editing by Dan Grebler and Leslie Adler)