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A century-old sand dike that held back the raging Wisconsin River helped protect a rural neighborhood, but state officials said Tuesday they'll renew a push to buy out homeowners and let the levee deteriorate.

The river surged around one end of the levee, leaving low-lying portions of the Blackhawk Park neighborhood in Caledonia under more than a foot of dirty water. But after three days of flooding, residents who evacuated Sunday were expected to return Wednesday, officials said.

Even though the dike held, water seeped through it. The situation underscored experts' concerns that many levees across the nation are aging and weren't designed to hold back big floods. The National Committee on Levee Safety warned in a report to Congress last year that inattention to poorly built levees has put more people and structures at risk over the past 100 years.

Portions of the upper Midwest have seen severe flooding over the past few days as heavy rains moved through the region.

Federal and state officials assessed damage in southern Minnesota on Tuesday, while St. Paul Mayor Chris Coleman declared a flooding emergency. The Mississippi River was expected rise to nearly 18.5 feet by Saturday afternoon — 4.5 feet above flood stage.

White House spokesman Bill Burton issued a statement saying President Barack Obama's administration has been in constant contact with the governors in Wisconsin and Minnesota and the U.S. Army Corps of Engineers was providing sandbagging and other help. The statement came as Obama appeared at a campaign rally for Democratic candidates in Madison.

A band of farmers and homeowners built the levee in Caledonia in the 1890s to protect farms from flooding. The town lies about 40 miles north of Madison, in the swamps where the Baraboo and Wisconsin rivers meet and Interstates 90/94 and 39 converge.

The 14-mile-long berm made of sand and grass runs along the Wisconsin River's southern shore. Most of it separates the Pine Island Wildlife Area from the river, but the last mile-and-a-half on the western end walls off Blackhawk Park, a collection of about 100 homes and seasonal cottages.

It's unclear how much worse the flood might have been had the levee burst, but Steve Miller, director of the state Department of Natural Resources' Bureau of Facilities and Lands, said the levee's best days are over.

"We're just lucky it hasn't washed out," Miller said. "It's too old. It's dilapidated. It's poorly built. I'm pretty sure our position will be to look at a different way to manage the flood plain."

Many levees nationwide are similar — just mounds of dirt farmers piled up to protect crop land, said Eric Halpin, vice chair of the National Committee on Levee Safety.

"Many weren't designed to protect people at all," Halpin said.

A study group the Wisconsin DNR convened after Hurricane Katrina burst New Orleans' levees reported in 2007 that the berm couldn't be relied on to protect the community. The levee could actually make flooding worse if water backed up behind it and spread out, the group said.

"Reliance on these levies for providing flood protection elevates the risk of putting lives and properties in harm's way," the group's report said.

The DNR will continue to maintain the dike, but major upgrades would cost millions of dollars per mile, Miller said. He believes it would be cheaper to buy out homes in the flood plain and let the levee erode, although just how much that would cost isn't known.

The most logical next step would be to work with the Federal Emergency Management Agency and secure funding for buyouts, Miller said. The DNR had started talking with local government officials about making such a move in 2008.

This weekend's floods should re-energize the talks, Miller said.

But Steve Pate, chairman of the Town of Caledonia Board, said he believes the DNR should go on maintaining the dike. The levee keeps floodwater from blocking Interstate 39 and clearly kept things from getting worse last weekend, he said.

"I think we have an interest in having it maintained," Pate said.

Another board member, John Exo, said he hasn't made up his mind about the DNR's plan, but in general, he doesn't believe in blocking flood plains.

"You're just making the problem worse for someone else downstream," Exo said. "It will be a healthy discussion after the water goes down."