Heavy rains Saturday night and early Sunday forced the closure of 21 flooded streets throughout Howard.
By early yesterday, all roads were open, county officials said.
"At 5 p.m. [Sunday], you still couldn't see South Entrance Road" in Columbia's Town Center, said Sgt. Robert Wiseman, a spokesman for the Howard County Department of Fire and Rescue Services.
Most of the flooding occurred in the West Friendship area, he said.
Some of the roads were covered by as as much as 4 feet of water, Sergeant Wiseman said. Normally shallow sections of the Patapsco River in Ellicott City and Woodstock crested at 10 feet, but no major damage was sustained, he said.
"The time of day played in our favor," said Sergeant Wiseman,
Some portions of the county got up to 6 inches of rain, most of which fell between 10 p.m. Saturday and 2 a.m. Sunday.
Fire and rescue workers evacuated residents at an Elkridge mobile home park Sunday when a storm drain there clogged, causing the area to be flooded.
One man ignored warning signs and drove around a barricade at the intersection of Burnt Woods and Sharp Road in Glenwood, only to be trapped in water 2 1/2 feet deep, authorities reported.
His vehicle had to be towed away.
Bridges on the 14000 block of Rover Mill Road in West Friendship were flooded with 1 1/2 feet of water early Sunday and nearby McKendree Road also was inundated, Sergeant Wiseman said.
Old Columbia Road at Route 29 near Scaggsville and Meadow Ridge Road in Elkridge also were closed, emergency officials said.