CHAMPAIGN, Illinois -- Authorities in a southern Illinois city menaced by two dangerously swollen rivers said Sunday that most of the city's remaining residents have heeded a mandatory evacuation order, prompted by river water seeping up through the ground behind a levee.

Passing thunderstorms dumped rain overnight on the already waterlogged region, and water levels hit a record along the Ohio River early Sunday, adding to the worries of emergency officials. But a decision has not been made whether to blast a hole in the Birds Point levee downstream from Cairo, a move that could protect the city from flooding but cause water to flow into 130,000 acres (52,600 hectares) of nearby farmland.

Cairo Mayor Judson Childs ordered the city's 2,800 residents to leave by midnight due to a "sand boil," an area of river water seepage, that had become dangerously large. He made the decision after meeting with Maj. Gen. Michael Walsh, the Army Corps of Engineers officer tasked with deciding whether to breech the levee to relieve pressure on levees along the dangerously high Ohio and Mississippi rivers.

At 4 a.m. (1000 GMT) Sunday, the Ohio River topped a 1937 record of 59.50 feet (18.14 meters) by reaching 59.59 feet (18.16 meters) in Cairo, the National Weather Service reported. Police said there was no indication that anyone had defied the evacuation order, but officers still planned to go door to door.

Authorities had taken note of the new level but were gratified that the boil area appeared to hold "stable" throughout the night, said Jim Pitchford, a spokesman for Cairo's emergency services. He said the seeping water was being continuously monitored by corps officials, who were out checking the pumps during the night.

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Walsh, who toured Cairo's levee area, recently described the boil -- which has been growing since it was spotted Tuesday -- as the largest he had ever seen, the Southeast Missourian newspaper reported. Sand boils occur when high-pressure water pushes under flood walls and levees and wells up through the soil behind them. They're a potential sign of trouble.

City clerk Lorrie Hesselrode described the boil as "kind of like Old Faithful," the famous geyser in Yellowstone National Park in Wyoming. "There's so much water pressure it forces the water under ground."

"It's kind of scary. It's pretty big. We've had sand boils before but nothing like this. It is under control but other boils have popped up," she told The Associated Press.

The river is expected to crest in Cairo at 60.5 feet (18.44 meters) by Tuesday and stay there through at least Thursday afternoon, according to the National Weather Service. A flood wall protects Cairo up to 64 feet (19.51 meters), but the corps fears that water pressure could compromise the wall and earthen levees that protect other parts of the city.

The corps inched closer Saturday to blowing a hole in the Birds Point levee after a federal appeals court declined to stop the move. The corps moved a pair of barges loaded with the makings of an explosive sludge into position near the levee, which is on the Mississippi River just downstream from Cairo in Missouri, but said it hadn't decided that it needed to breach the 60-foot (18.29-meter)-high earthen wall.

The 230 people who live in the southeast Missouri flood plain behind the levee had already been evacuated from their homes, a spokesman for Missouri Gov. Jay Nixon said. Some of the farmers whose roughly 130,000 acres (52,600 hectares) of land would be inundated moved out what they could Saturday, assuming the corps would have no choice as the Mississippi and Ohio rivers rise.

In Cairo, the mayor said he was relieved that the 8th U.S. Circuit Court of Appeals decided Saturday to allow the corps to breech the levee if it deemed it necessary. Cairo is just north of where the Ohio flows into the Mississippi.

"I've been saying all along that we can't take land over lives," Childs said.

The state of Missouri had asked the court to block the plan to protect the farmland. The governor's spokesman, Scott Holste, said state officials in Missouri are now focused on protecting homes, agricultural equipment and other property left behind in the heavily farmed flood plain below the levee. In addition to people evacuated from the floodway, as many as 800 were asked to leave surrounding areas.

Holste said more than 600 Missouri National Guard troops are helping local law enforcement at checkpoints around the area.

It's unclear whether Missouri could pursue further legal action. Holste referred questions to Attorney General Chris Koster, whose didn't respond to phone calls or emails Saturday from The Associated Press.


Associated Press writers Bill Draper in Kansas City, Missouri, and Jim Salter in St. Louis contributed to this report.