Dozens Remain Stranded in Flooded Portage, Wisc.

Updated at 11:47 a.m. ET

Dozens of residents have opted to stay in their flood-stranded homes in central Wisconsin, even as a nearby levee weakened by recent heavy rain barely holds.

Columbia County Emergency Management director Pat Beghin said the levee on the Wisconsin River has deteriorated in the Town of Caledonia, just west of Portage. The river has been swollen by recent thunderstorms.

Beghin said if the levee breaks it could destroy an already flooded access road to the town's Blackhawk Park neighborhood. Some 75 of 300 area residents have decided to stay in their homes.

Wisconsin Department of Natural Resources engineers are inspecting the 14-mile levee system, which includes some dikes built mainly of sand in the 1890s.

Beghin said authorities are monitoring riverside towns where minor flooding has occurred.

Kathy Matavka said she was taken from her home by boat after she received a second call urging her to evacuate.

"If I didn't sit there and take the boat, I would be stuck. I would not be able to get groceries. I would not be able to get medications I need to take," Matavka told WISC-TV in Madison.

Kevin Remus told the Portage Daily Register that he and his wife decided to leave their home with their 17-month-old daughter because they were concerned about being cut off from the outside word. Their house wasn't likely to flood because it's on a hill, but the access road was already covered in 6 inches of water by the time the family was ready to leave.

His wife, Lindsay, said the family planned to stay in a motel for a few days.

"It's kind of a feeling of hopelessness," she said. "The water is out of control."

The flooding was the result of extraordinarily heavy rains that fell across the upper Midwest last week - as much as 10 to 12 inches in some areas, reports CBS News correspondent Cynthia Bowers.

The Wisconsin River is swollen from thunderstorms last week that dumped several inches of rain in southern Minnesota and central Wisconsin.

The Columbia County Emergency Management Office warned residents in the Blackhawk Park area that emergency vehicles, including police, fire and ambulances, would not be able to reach those who stayed behind.

"The residents down there are used to having high water and dealing with high water a lot but this could be something that they've never seen, with this amount of water," said Kathy Johnson, deputy director of the Columbia County Emergency Management Office.

Johnson said those who evacuated might be out of their homes for up to a week, and the Red Cross opened a shelter at a local church.

Elsewhere, in the small South Dakota town of Renner, just north of Sioux Falls, thousands of sandbags were being filled to deal with any unexpected rise of the Big Sioux River.

The National Weather Service expects the river to crest Monday morning about 4 feet over flood stage.

The Big Sioux River has been running high all summer. Heavy rain last week pushed the river over its banks from Brookings south to Sioux Falls.

In Minnesota, residents of Zumbro Falls and Hammond - two of the cities hardest-hit by flooding from last week's heavy rains - got a chance to briefly go to their homes to fetch medications or other essentials. It was the first look many had of the damage.