Portland residents and businesses cleaned up Thursday in the wake of a drenching downpour that flooded streets and basements in a matter of hours Wednesday.

Nearly 6 inches of rain fell in Portland during one of the city’s rainiest days on record, with torrential rains at the peak of the storm dropping 2.22 inches in an hour. The storm caused flash flooding in parts of the city, leading to road closures and stranded drivers.

Streets in Portland that were covered with waist-deep water Wednesday were mostly dry Thursday. On Somerset Street, where several cars had been stuck in the water, the only remaining signs of the flood were mud in the road and a crumbled retaining wall next to Whole Foods Market.

AAA of Northern New England responded to 1,600 calls for roadside assistance Wednesday in Maine, New Hampshire and Vermont, about 600 more than a typical day. Spokesman Pat Moody said the 350 calls in Portland and South Portland included many cars that were flooded or stuck. AAA crews from New Hampshire were called in to help deal with the high call volume.

Whether a car is a total loss after being flooded depends on the depth of the water and whether the driver tried to start the engine afterward, said Tom Gaisson of AAA in Portland. If water rises above the floorboards and into the engine compartment, the car should be towed to a mechanic to be checked out. Cars that were in freshwater often can dry out and be fine, but saltwater can cause irreversible damage.

Gaisson said the most important thing to remember with a flooded car is not to start it, especially if the owner doesn’t know how high the water rose.

“Once you fire up the engine, that’s when trouble occurs,” he said.

HIGH WATER PLAGUES WHOLE FOODS

Mona Freeman of Clark Insurance in Portland said most comprehensive auto insurance policies cover flood damage, but that doesn’t necessarily make dealing with the damage easy.

“It can be tricky if they don’t dry their car out right away,” she said. “If the water stays in the car and gets musty, it can be an ongoing issue.”

Much of the flooding that damaged cars in Portland was in the area of Whole Foods Market, where several cars were inundated on Somerset Street when water rose quickly.

Frank Keenan, owner of Keenan Excavating in Scarborough, said his crews were called into Portland on Wednesday when the parking lot at Whole Foods flooded. The company handles heavy maintenance for the store, such as plowing, and has dealt with flooding there before, but nothing like Wednesday’s rain.

“They called us when they had 6 feet of water,” he said. “They’re always impacted by the astronomical high tides, so we’re always battling that. But I have never, ever seen water that high up along there.”

When the water receded, the store parking lot and a nearby parking lot for employees were strewn with bark mulch, gravel and chunks of concrete. A retaining wall along the side of the building crumbled. Keenan said his crew cleared away debris to make the sidewalk passable, then returned Thursday morning to pump out the employee parking lot.

“Everything will dry out today,” he said.

DRYING OUT FLOODED BASEMENTS

In Brunswick, River Road was reopened Thursday evening, 24 hours after a flash flood from Wednesday’s downpour destroyed a culvert that runs under the road. An emergency dispatcher said the road, near its intersection with Rocky Hill Road, reopened around 6 p.m.

The rain also flooded basements throughout the area.

Holly Merrill, marketing manager for Gorham-based Servpro, said the company was inundated with calls from homeowners and businesses with flooded basements, primarily in Portland, South Portland and Yarmouth. She said the company responded to about 50 residential calls and about 25 from businesses.

“Our phones will start to ring with 3 inches (of rain) or more,” she said. “With that much rain yesterday, we were expecting a high call volume. It was all hands on deck.”

Merrill said the water had already receded in most basements after the rain stopped Wednesday evening, but people still wanted to make sure their basements were drying properly. Crews spent Wednesday placing fans and dehumidifiers and went back out Thursday to check.

Freeman, from Clark Insurance, said most homeowner insurance policies don’t cover damage from surface water, which is likely what caused much of the flooding Wednesday.

“If you have water that comes in through your foundation or bulkhead, that’s considered surface water and is not covered,” she said.

HURRICANE MAY BRING MORE FLOODING

Freeman said she took a call from one customer who had water in his basement, but because the damage came from surface water, insurance would not cover it. “He was not a happy camper,” she said.

Freeman suggests that people prepare before heavy rains to reduce the risk of flooding, including making sure sump pumps are working and buying generators in case the power goes out. She also recommends that homeowners talk to their insurance providers about policy enhancements that cover water damage or, if the residence is in a flood-prone area, purchase separate flood insurance.

And more flooding is possible.

Servpro employees are keeping an eye on Hurricane Joaquin, a dangerous Category 4 storm that was sweeping through the Bahamas on Thursday. The storm is predicted to turn north-northwest toward the U.S. by Friday, but forecasters were still determining where it will track and how it might affect the East Coast.

National Weather Service meteorologists in Maine said the next few days will be dry, but rain will move in again by the end of the weekend or early next week.

Staff Writer Dennis Hoey contributed to this report.