Storm-weary New England residents waded out into a fifth day of rain Tuesday as the region's dams kept a tenuous hold against cresting rivers and evacuees wondered what remained of their homes after water filled their basements and surged over some rooftops.

Across northeastern Massachusetts, thousands of people fled submerged neighborhoods during the region's worst flooding in nearly 70 years. More than a foot of rain fell during the weekend in some areas.

"It seemed almost Biblical," Gov. Mitt Romney said Tuesday on ABC's "Good Morning America." "We're sort of making jokes about Noah and taking two of each kind of animal because we haven't ever seen rain like this."

The stubborn storm system lingering over the region was expected to move out by Wednesday, and Peter Judge, a spokesman for the Massachusetts Emergency Management Agency, said the worst of the flooding appeared to be over.

But Tuesday morning, commuters still awoke to another day of driving rain.

In Lowell, crews took to the streets in boats and used bullhorns to urge 1,000 households to evacuate. Nick Barrett, 24, took an air mattress when he left his condominium overlooking the Merrimack River, and later joked it might become a raft.

"I'm going to use it to get back in, too," he said late Monday night as he looked over the flooded parking lot of his building.

In New Hampshire, more than 600 roads have been damaged, destroyed or inundate by water. In Maine, flooding washed out dozens of roads and bridges, and threatened a pair of dams along the swollen Salmon Falls River in Lebanon. Two areas of Lebanon near the Spaulding Dam were evacuated Monday as a precaution.

The rising water of Pillsbury Lake in Webster, N.H., breached a dam Monday, releasing millions of gallons of water and threatening to drain the lake. The water eroded the earth from one side of the dam and began running into woods and downstream to the Contoocook River, causing some flooding and forcing the evacuation of several families.

Several hundred residents in Methuen, Mass., also left their homes after officials became concerned that the Spicket River Dam, shored up by several thousand sand bags, would give way under the pressure of the raging river.

Even though the ferocious water tore away a wooden walkway across the top of the dam and knocked over a nearby lamp post, the concrete structure kept a tenuous hold when the river crested early Tuesday.

"We still have dams holding back a lot more water than they were designed to carry," Romney said on CBS' "The Early Show" Tuesday. "This is what you can expect when you've got a storm that's bigger than anything we've faced in 70 years."

U.S. Route 1 north of Boston was expected to remain closed for the Tuesday morning commute, state police said. Large portions of the highway between Route 16 in Revere and the interchange with Route 128 in Lynnfield were underwater, forcing the shutdown of dozens of businesses.

Schools across the North Shore and Merrimack Valley as well as in southern New Hampshire closed for a second day Tuesday.

The flood water also overwhelmed sewage systems and drowned waste water treatment plants. Burst pipes in Haverhill have been dumping 35 million gallons of waste a day since Sunday into the Merrimack River. A flood at a regional treatment plant in Lawrence was threatening to shut down the power there, which would send sewage into the Merrimack at a rate of 115 million gallons a day.

The statewide damage was expected to reach the tens of millions of dollars, Romney said Tuesday. He said officials were also concerned about the long-term environmental impact of the sewage on shellfish beds.

"This is gonna be a big financial crisis for a lot of people," he said.