"Water is still our primary concern," said Pat Ball, the city's utilities director. "We're still using water at a greater rate than we're producing."
More than 400 city blocks and 3,900 homes were flooded in Cedar Rapids, where early estimates put property damage at $736 million, according fire department spokesman Dave Koch.
While the Cedar River ebbed in hard-hit Cedar Rapids, a levee breach in the state capital of Des Moines flooded a neighborhood of more than 200 homes, a high school and about three dozen businesses.
In Iowa City, more than 200 homes were evacuated because of the flooded Iowa River, expected to crest Monday or Tuesday. People filled thousands of sandbags at the University of Iowa but officials were conceding some buildings to the expected flooding.
"We've pretty much just abandoned any effort to try and protect the Arts Campus because we are just overwhelmed by the amount of water," university spokesman Steve Parrott said. "It's just too unsafe." Valuable paintings have been removed from the art museum, he added.
At least three deaths in Iowa have been attributed to the storms and subsequent flooding, and 12 more have died in two recent tornadoes. The storms have prompted the governor to issue disaster proclamations for 83 of the state's 99 counties.
President Bush was briefed on the flooding in Iowa and other parts of the Midwest while he was in Paris, and was assured that federal agencies are making plans to help people affected by the high water, White House press secretary Dana Perino said.
"He expressed his concern for people who may still be in danger and for those who are hurting from the impact of the storms," Perino said.
Elsewhere, Illinois emergency authorities said a levee along the Mississippi River in far western Illinois burst Saturday morning and voluntary evacuations were under way in Keithsburg, a town of about 700 residents.
"The levee broke in two places," said Keithsburg Alderman George Askew, 76. "We're getting under water."
Farther south, rising water prompted officials to close a bridge over the Mississippi connecting Quincy, Ill., to Missouri. Authorities were sandbagging an area around a water treatment facility and other nearby businesses as a precaution.
Democratic presidential candidate Sen. Barack Obama toured Quincy and helped fill sandbags Saturday.
"Since I've been involved in public office we've not seen this kind of devastation," Obama said of the Midwest flooding. He vowed to push the federal and state governments to provide needed aid to the stricken areas.
Parts of southern Wisconsin have been dealing with flooding for days, and Bush declared disasters in five counties there Saturday.
Iowa's worst damage so far was in Cedar Rapids, a city of more than 120,000. The Cedar River crested there Friday night at nearly 32 feet, 12 feet higher than the old record set in 1929. City Engineer Dave Elgin said the Cedar River was dropping at a rate of about 2 inches an hour Saturday.
Murky, petroleum- and garbage-choked water inundated three collection wells and threatened the fourth before several hundred volunteers staged a last-ditch sandbagging operation.
Water lapped to within 3 feet of the improvised, 4-foot-high wall surrounding the brick pumping station before it began to recede. Two portable generators, one as big as a semitrailer, roared around the clock to keep the three pumps inside running.
"It's the little engine that could," said Ron Holtzman, one of several people who came to watch the operation Saturday from a nearby foot bridge.
Residents not forced to leave their homes took the warnings to conserve seriously.
Kathy Wickham, 65, was collecting water from the dehumidifier in her basement and has been bathing from the 6-inch-deep enamel washbasin she used as a child on the farm.
"I grew up without any running water, so I'm going back to my childhood," she said.
Raejean White posted bright yellow signs at all six entrances to the Preston Terrace Condominiums that read: "If it's yellow let it mellow. If it's brown, flush it down."
In Catherine Holt's household, there are nine children ranging in age from 2 to 17 -- including four teenage girls. She said they're making do with baby wipes and water stored earlier in the week in milk jugs and soda bottles.
"So what if it stinks?" said Holt, who closed off one of the family's two bathrooms and forbade the children from using any faucets. "This is so minor compared to what other people are going through."
About 100 miles to the west in Des Moines, a levee ruptured early Saturday and the Des Moines River poured into the Birdland neighborhood near downtown. A mandatory evacuation was ordered for 270 homes; many of those residents had left after a voluntary evacuation request Friday.
Des Moines city crews and National Guard units started to build a temporary berm in a bid to stop the water, but by midmorning the water had cut through mounds of dirt and sandbags and inundated the homes and other buildings, including North High School.
"Things happened really fast," said Toby Hunvemuller of the Army Corps of Engineers. "We tried to figure out how high the level would go. Not enough time. We lost ground."
Authorities knew the aging levee near Birdland, a working-class, racially diverse neighborhood, was the weakest link among the city's levees. A 2003 Corps report called for nearly $10 million in improvements across Des Moines, but there wasn't enough federal money to do all the work.
"This was the first to fail, and we felt it was the one likely to fail," said Bill Stowe, the city's public works director.
Some residents were upset that other areas of city have received more flood-control improvements than Birdland since massive floods hit the area in 1993.
"In the short term they did a great job with the buildup of the sandbags. But they should have known this was coming," Chris Lucas said at a shelter.
In southeast Iowa, authorities told all the roughly 250 people in Fredonia to leave their homes ordered more evacuations in two other small towns, Columbus Junction and Columbus City. The communities are clustered near the junction of the Iowa and Cedar rivers.
Iowa has had a wet spring and at least 8 inches of rain since June 6. More thunderstorms are possible in the Cedar Rapids area during the weekend, but next week is expected to be sunny and dry.