Officials guess it will be four days before the Cedar River drops enough for workers to even begin pumping out water that has submerged more than 400 blocks, threatened the city's drinking supply and forced the evacuation of a downtown hospital.
"We're estimating at least a couple of weeks before the flood levels get down right around flood stage and below," said Dustin Hinrichs of the Linn County emergency operations center.
The Cedar River crested Friday night at nearly 32 feet, 12 feet higher than the old record set in 1929.
Even as the river slowly recedes, officials worried that the city's supply of fresh drinking water would run out. Only one of the city's half-dozen wells was working, and it was protected by sandbags and pumps powered by generators.
The damage in Cedar Rapids was extensive, with preliminary damages estimates in Cedar Rapids of $737 million, and officials foresee a long recovery.
"It's a bit overwhelming ... " said the city's mayor pro-tem, Brian Fagan. "This is an endurance competition. We have to be patient. We have to be cooperative."
In Des Moines, a levee ruptured early Saturday and allowed the Des Moines River to pour into an area near downtown, and a mandatory evacuation was ordered for 270 homes, authorities said. Many residents of the area already had left after a voluntary evacuation request was issued Friday.
Des Moines city crews and National Guard used dump trucks and front-end loaders to build a temporary berm of dirt and sandbags in a bid to stop the water before it flowed out of the largely business area and into more populated neighborhoods. By midmorning, the berm stretched about a half-mile long.
Water pouring through the 100-foot-wide gap in the levee surrounded the city's North High School, and in places the water was up to 4 feet deep.
Just south of Cedar Rapids, in Iowa City, Gov. Chet Culver warned that more dramatic flooding could be on the way as the Iowa River rises.
"A real wave of water is on the way as we speak," he said.
In Cedar Rapids on Friday the full scope of the damage was becoming clear. At least 438 city blocks were under water, hospital patients in wheelchairs and stretchers were evacuated in the middle of the night, and officials said as many as 10,000 townspeople had been driven from their homes in this city of 120,000.
The flooding was blamed for at least two deaths in Iowa: a driver was killed in an accident on a road under water, and a farmer who went out to check his property was swept away.
Since June 6, Iowa has gotten at least 8 inches of rain. That came after a wet spring that left the ground saturated. As of Friday, nine rivers were at or above historic flood levels. More thunderstorms are possible in the Cedar Rapids area over the weekend, but next week is expected to be sunny and dry.
Gov. Chet Culver declared 83 of the state's 99 counties disaster areas, a designation that helps speed aid and opens the way for loans and grants.
The drenching has also severely damaged the corn crop in America's No. 1 corn state and other parts of the Midwest at a time when corn prices are soaring. Dave Miller, a grain farmer and director of research for the Iowa Farm Bureau, estimated that up to 1.3 million acres of corn and 2 million acres of soy beans - about 20 percent of the state's overall grain crop - had been lost to flooding.
"Farmers have already put a lot of resources into a crop that is now underwater," Miller said.
At Cedar Rapids' Prairie High School, where 150 evacuees waited, people could be seen crying in the cafeteria while others watched flood coverage on TVs set up in the gym. Tables were lined with shampoo, toothpaste, contact lens solution and other items, and piles of clothes were separated by size.
At the school, Lisa Armstrong wept as she watched TV news footage of her own rescue. She saw herself climbing into a boat, and watched rescuers trying to coax her dog out of the house. They finally grabbed the animal and pulled it out.
"I didn't think it was going to be as bad as it was, and we should have got out when we were told to leave," she said. "I didn't think or imagine anything like that."
The shelter was the third stop for Don Webster and his family, after his mother-in-law's house and then a stepson's place. Holding his 4-year-old grandson, Leroy, he said he planned to stay for a few days, then "just pray and hope there's something when you go back."
"We really need to reduce the amount of water we are using," Koch said, "even using paper plates, hand sanitizer."
Hotels implored guests to use water only for drinking.
The city's newspaper, The Gazette, continued to cover the story with the help of emergency generators. But the floodwaters were just outside the front door, and the place had no running water. Portable bathrooms were set up outside for the staff.
"We're putting the paper out through heroic, historic effort by the staff companywide," said Steve Buttry, who started as editor of the newspaper on Tuesday - just one day before the disaster struck.
In Des Moines, fire officials had no immediate estimate of the number of people who were urged to evacuate. Mayor Frank Cownie said the evacuations were an attempt to "err on the side of citizens and residents."
Interstate 80 was closed east of Iowa City to Davenport after the Cedar River washed over the highway. Amtrak service aboard the California Zephyr was suspended between Denver and Chicago because of flooded-out tracks. Alternate transportation was being provided by bus between Denver and cities in Nebraska including Omaha, Neb., but none was being provided in Iowa.