A levee on the Illinois side of the Mississippi River broke Tuesday in a region already battered for days by severe flooding.

The breach happened just across the river from Burlington, Iowa, in Henderson County, Ill. Police subsequently shut down a bridge six miles to the south.

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The federal government predicted that a total of 27 levees could potentially overflow along the river if the weather forecast is on the mark and a massive sandbagging effort fails to raise the level of the levees, according to a map obtained Monday by The Associated Press.

The breached levee meant there were 26 more that could burst.

The BNSF Railway Co. swing span bridge over the Mississippi was closed early Tuesday to car traffic at Fort Madison, near the Iowa-Illinois line, Lee County emergency management director Steve Cirinna said.

About 30 people were working to raise the railroad tracks above floodwaters, but BNSF Railway Co. spokesman Steve Forsberg said the bridge hadn't closed to trains.

Car traffic moves on the bridge and trains travel on tracks below.

The banks of the rising Mississippi were stacked with sandbags as the rest of Iowa began the slow move from protection to cleanup.

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Officials placed millions of sandbags on top of the levees in Illinois, Iowa and Missouri to prevent overflowing. There was no way to predict whether the levees would break, said Ron Fournier, a spokesman with the Army Corps of Engineers in Iowa.

In much of Iowa, there were small signs of a return to normalcy: Interstate 80 reopened near Iowa City for the first time in days, with Interstate 380 to the north scheduled to reopen early Tuesday. On the University of Iowa campus, officials began to take stock of the damage.

One woman forced to evacuate her home had to take a row boat through the flooded streets with her 7-month-old baby and husband.

"There was a lot more water than I expected there to be, honestly," Jamie Duff told FOX News. "It was insane."

In Des Moines, where a levee failure Saturday sent water pouring into the Birdland neighborhood, some residents returned for the first time to see the damage.

"It's really bad. I mean, I can't believe this," said Gloria Ruiz, whose home suffered flood damage.

Ruiz pointed to a dirty line about 5 feet up on her basement wall showing how high the water rose. Her washer, dryer and boiler, and most of her children's toys, including a stereo and an Xbox video game system, were ruined.

Floodwaters lingered about 50 feet from her driveway.

"We don't know how long it will stay like that," she said.

Where floodwaters remained, they were a noxious brew of sewage, farm chemicals and fuel. Bob Lanz used a 22-foot aluminum flatboat to navigate through downtown Oakville, where the water reeked of pig feces and diesel fuel.

"You can hardly stand it," Lanz said as he surveyed what remained of his family's hog farm. "It's strong."

LeRoy Lippert, chairman of emergency management and homeland security in nearby Des Moines County, warned people to avoid the floodwaters: "If you drink this water and live, tell me about it. You have no idea. It is very, very wise to stay out of it. It's as dangerous as anything."

Gov. Chet Culver and others pointed to the next looming trouble spot, in southeastern Iowa. Most requests for state aid were coming from Des Moines County, where the Mississippi River was expected to crest Tuesday evening at 26 feet in a mostly rural area near Burlington. Early Tuesday, the river was at 25.7 feet — more than 10 feet above flood stage — and still rising.

Crews were working to shore up a levee about 7 miles north of Burlington, where water covered about 2 blocks of the downtown area. Several businesses spent the night pumping water from basements, said Sgt. Chad Zahn of the Burlington Police Department.

Several thousand acres and about 250 homes would be flooded if the levee breaks, said Gina Hardin, the county's emergency management coordinator.

Brian Wiegand, 48, of Oakville, was sandbagging the levee Monday evening near a drainage pumping station. He was concerned about more flooding as water began lapping to within a foot of top of sandbag wall.

"The Bible says the prayer of one man, God hears," Wiegand said. "Here's my prayer: I ask for the strength of God to fight this flood, and I ask for the grace to accept whatever happens."

On the Illinois side of the river across from Burlington, a levee broke Tuesday morning south of Gulfport, Ill., forcing the closure of a bridge that connects the two cities.

Two more deaths were reported Monday in Iowa, bringing the state's death toll to five.

Also Monday, the American Red Cross said its disaster relief fund has been completely spent, and the agency is borrowing money to help flood victims throughout the Midwest.

In the college town of Iowa City, damage appeared limited. Some 400 homes took on water Sunday, and 16 University of Iowa buildings sustained some flood damage over the weekend. But the town's levees were holding and the Iowa River was falling.

Officials in Illinois were building up the approach to the only major bridge over the Mississippi River linking Hamilton with Keokuk, Iowa, so the bridge could stay open despite rising water.

In Cedar Rapids, hazardous conditions forced officials on Monday to stop taking residents into homes where the water had receded. Broken gas lines, sink holes and structural problems with homes made conditions unsafe, said Dave Koch, a city spokesman. Officials hoped to allow residents in soon.

Frustrations spilled over at one checkpoint, where a man was arrested at gunpoint after he tried to drive past police in his pickup truck.

All manner of refuse could be seen floating down the Iowa River — 55-gallon drums labeled "corrosive," propane tanks, wooden fences and railroad ties. Dead birds and fish sat on the city's 1st Avenue Bridge.

A few blocks away, a paint store stood with its windows blown out. A line indicating the high-water mark could be seen about 8 feet above the floor. At the gas station next door, strong currents had knocked over two pumps.

Also mixed into the floodwaters are pesticides, herbicides and fertilizer from Iowa's vast stretches of farmland.

Ken Sharp, environmental health director for the Iowa Department of Public Health, acknowledged that the floodwaters had the potential to make people sick. But he said the sheer volume of water can dilute hazardous substances.

"We don't typically see mass cases of disease or illness coming from floodwater, but under any circumstance like this, we want people to avoid it because we don't know what's in there," he said.

The flooding also raised concerns of contamination in rural wells, said G. Richard Olds, professor and chairman of the Medical College of Wisconsin.

"For rural folks, it's going to be hard to know if their water's safe or not," he said.

In addition to the poison in the water, there are mosquitoes — millions of them spawning in acres of standing water. Greg Burg, assistant director of undergraduate biology at the University of Kansas, said the flooding "adds that much more water where they could potentially lay eggs and have the eggs survive."

Business was already heating up at Mosquito Control, a Rolfe, Iowa-based company that sprays insecticide from a crop-duster airplane.

Near Iowa City, Angela Betts and her three children were among those who fled last week when the Iowa River burst through a levee at Coralville. She stayed just long enough to fill two trash bags with clothes.

The family is now living in a shelter, and as far as Betts is concerned, everything she left behind can stay there.

"It bothers me, with everything that's in the water," she said. "I probably won't keep anything. It won't be worth it."

Click here to read more on this story from KDSM.com.

FOX News' William LaJeunesse and The Associated Press contributed to this report.