The Lake Delton breach was caused by violent, drenching weekend thunderstorms that threatened the survival of the tiny Wisconsin town of Gays Mills and displaced thousands of Indiana residents. The stormy weather was blamed for 15 deaths in the Midwest and elsewhere.
Also, the East Coast is being baked by a heat wave. Heat watches and advisories were in effect Tuesday from North Carolina to New Hampshire. New York City recorded a high of 99 on Monday at La Guardia Airport, with 96 at the heart of the city in Central Park.
Scores of schools around the Northeast planned early closings for a second day in classrooms that lack air conditioning. Agencies in Wilmington, Del., appealed for donations of fans and air conditioners for needy residents.
In the past two days, records broke in nearly 50 places including northwest Georgia, which sizzled at 103 degrees, reports CBS News correspondent Bianca Solorzano.
One engineering assessment team from the Wisconsin National Guard headed to Lake Delton to determine what equipment and supplies will be needed to repair the gaping hole that let water from the 267-acre lake carve a new channel to the Wisconsin River on Monday.
Other crews were going to dams throughout the southern and western part of the state to assess damage.
They also were monitoring several dams that were seeping or in danger of failing, state Emergency Management spokeswoman Jessica Iverson said.
However, no significant damage had been reported at any of the dams, she said.
The downpours in states like Iowa, Illinois and Indiana flooded corn fields and made it difficult for farmers to plant, pushing corn prices to record highs on commodities exchanges this week.
New storms during the night knocked out power to more than 50,000 customers in Ohio, utilities reported Tuesday. Michigan utilities said about 247,000 customers were still blacked out because of the weekend storms.
The collapse of the embankment at Lake Delton swept away three houses and tore apart two others.
Don Kubenik, 68, burst into tears after seeing the 2,800-square-foot home he built in 2003 snapped into pieces. The businessman from the Milwaukee suburb of West Allis said he spent every weekend there.
"That house had everything you can imagine and now it's all gone," said Kubenik, who was in West Allis when the lake overflowed. "My boat's gone. The pier's gone. Everything is gone."
Lake Delton, a key part of the Wisconsin Dells tourism area, was nearly dry by Monday afternoon. The 20 resorts that line the lake already are reporting cancellations by people who had planned summer vacations in the area.
About 70 miles southwest of Lake Delton, the village of Gays Mills was inundated during the weekend, just 10 months after another devastating flood left residents working to rebuild homes and businesses.
The swollen Kickapoo River engulfed nearly the entire town Monday morning, forcing about 150 of the 625 residents to evacuate. By evening, the village was a grid of canals with cars submerged up to their windows, just as it was last August.
"I can't believe this is happening again," said Liz Klekamp, 23, who said she grabbed her cat and fled Monday morning when water poured into her house. "It's really, truly sad."
Asked if this was the end of the town, Village President Larry McCarn just stared and said: "It could be."
In waterlogged Indiana, military crews joined desperate sandbagging operations Monday to hold back streams surging toward record levels, and rushing water breached dams and washed out portions of highways.
Indiana officials said they could not give a dollar estimate on the damage or the number of homes and businesses destroyed by flooding caused by up to 11 inches of rain on Saturday. Two more inches fell Monday.
Some 200 Indiana National Guard members and 140 Marines from North Carolina helped local emergency agencies sandbag a levee of the White River at Elnora, about 100 miles southwest of Indianapolis. The White River was forecast to crest Tuesday at nearby Newberry at 16 feet above flood stage.
Flooding in parts of Indiana had eclipsed levels set in the deluge of March 1913, which had been considered Indiana's greatest flood in modern times, said Scott Morlock, a hydrologist with the U.S. Geological Survey in Indiana.
The weekend's heavy rain and the threat of more heavy rain later this week could push corn prices even higher, analysts say, likely adding to Americans' growing grocery bills. The price of corn for July delivery jumped to a record of nearly $7 a bushel Monday on the Chicago Board of Trade, up from around $4 a year ago.
Indiana Gov. Mitch Daniels asked U.S. Agriculture Secretary Edward Shafer to declare farm disasters in 44 Indiana counties because of crop and livestock losses blamed on the flooding and other storms this month.
The weekend death toll included eight in Michigan, three in Indiana and one each in Iowa and Connecticut. Authorities said wet roads contributed to the deaths of two motorists in separate accidents Monday in Oklahoma, where more than 4 inches of rain fell.