The remnants of Tropical Storm Lee closed roads, schools and a commuter rail line in waterlogged Northern Virginia, and a retaining wall was brought down near a townhome complex, forcing evacuations.
At least four people have died in the Mid-Atlantic region because of the flooding.
Two men and a boy died Thursday night in three separate incidents in Fairfax County, where nearly 10 inches of rain fell in 24 hours, officials said.
In Maryland, the Susquehanna River reached a 15-year high of 32.4 feet Friday at the Conowingo Dam and was expected to remain near that level into the night, the National Weather Service said. Dam gates were opened to relieve pressure on the river.
Across the Baltimore-Washington area, flood waters inundated sewage-treatment plants.
Maryland’s congressional delegation asked the White House to declare a federal emergency so the state can apply for federal disaster aid.
More rain Friday added to the 13.5 inches that the region has endured since Monday. Sun was forecast Sunday for the first time in a week.
Commuters confronted scores of road closures and a complete shutdown of the Virginia Railway Express. The railroad, which serves suburbs south and east of Washington, said parts of both lines were under water and the track bed was washed out in at least one spot.
Trains were delayed Friday on Maryland’s MARC commuter rail lines.
About 150 people were evacuated Thursday night in Prince William County, Va., mostly from mobile home parks along U.S. 1 in the Woodbridge area after Marumsco Creek overflowed.
A four-tiered 50-foot retaining wall partially gave way behind a nearby townhome complex, forcing some evacuations there, county spokesman Jason Grant said.
“It was like Niagara Falls” said resident Felipe Bastos.
Fairfax County Police said 12-year-old Jake Donaldson died after he was swept away by flood waters in the backyard of his Fair Oaks home Thursday evening.
Arsalan Hakiri, 67, of Reston, was swept away along with his car and drowned when he tried to leave the vehicle, police said.
On Friday, Fairfax County Police released details from a third death Thursday night. Galo Sebastian Salvador Vinueza, 25, of Lorton died after he abandoned his car and tried to cross a flooded bridge on foot, police said. The road was where some of the worst flooding in northern Virginia occurred.
Military personnel found his body Friday on Nearby Fort Belvoir.
On Wednesday, Daniel Lambert, 49, of Pasadena, Md., died in flood waters.
In the flood-prone Huntington neighborhood near Alexandria, Cameron Run surged from its banks and covered some streets with eight feet of water even as people were preparing to move their cars. Homes in the neighborhood are on hills above street level.
“It came really quickly,” Betsy Thompson said.
Eric Bottary said it was eerie watching the water rise from a basement window: “It looks like a submarine because it’s submerged in water.”
Saul Romero borrowed a plastic storage bin to float his 2-year-old daughter up the street to dry land.
“I was just worried for my daughter,” he said, as he and others used hoses to wash inches of slimy mud off their sidewalks.
The same flash flood closed part of the Interstate 495, the Capital Beltway, overnight.
Mike Dixon of Cecil County’s emergency services agency was relieved that the river appeared unlikely to reach the nearly 36 feet that forecasters had predicted a day earlier.
“It’s still a serious flood, but it’s looking pretty good,” Mr. Dixon said.
In downstream Port Deposit, some residents paddled canoes in four feet of water covering Main Street.
Paddler Robert Hewitt, 47, was among about 60 people who stayed in town Thursday night despite a mandatory evacuation order covering nearly 1,000.
“If you’re not prepared, it’s insane,” Mr. Hewitt said. He said he had 10 gallons of drinking water and a bunch of ground beef that was defrosting because the power was out.
In Havre de Grace the flooding caused evacuations along the waterfront and closed a number of businesses on Friday.
Audrey Mylin said she came over from Perryville because she had heard the historic Concord Point lighthouse was flooded. She was relieved to find that flood waters had surrounded the lighthouse, but it did not appear to be damaged.
“Somebody said it was underwater, it’s not underwater, the road is,” said Ms. Mylin, 48.”This is a shame, I can’t get over all the junk floating.”
The lighthouse built in 1827 is one of the oldest in continuous operation on the East Coast and a popular spot for weddings and other gatherings.
“They told me it was underwater. I said ’Let me go see.’ I’m glad it’s not,” Ms. Mylin said as residents milled around the waterfront, surveying the flooding.
Ms. Mylin said flooding had also affected low-lying areas of Perryville, which lies across the river from Havre de Grace, but not her home.
In the District, the Department of Public Works continued to offer sandbags Friday at RFK Stadium.
The Prince George’s County courthouse and sheriff’s office headquarters in Upper Marlboro were closed due to flooding.
The Washington Suburban Sanitary Commission estimated that 12.7 million gallons of diluted raw sewage had escaped. It said the tap water it provides to customers in Montgomery and Prince George’s counties was safe for drinking.
The Anne Arundel County health department closed Cox Creek in the Brooklyn area because of a sewage overflow exceeding 10,000 gallons.
• Alex Dominguez in Port Deposit and David Dishneau in Hagerstown contributed to this report.
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