Kim Norvell, and Charly Haley

Des Moines Register

Flooding forced residents from their homes in the northeast Iowa towns of Greene and Clarksville on Thursday as the Shell Rock River jumped its banks following heavy storms that dumped up to 9 inches of rain in some areas.

Further downstream, residents in Cedar Falls, Waterloo and Cedar Rapids are preparing for the worst flooding to hit those cities since 2008, when Cedar River flooding dislocated more than 18,000 people in Cedar Rapids and caused more than $2 billion in damage to the city.

UPDATED FLOOD COVERAGE:

The Cedar River is expected to crest at 24.1 feet in Cedar Rapids early Tuesday morning. That's 12 feet above flood stage and second only to the record 31.12-foot crest eight years ago.

“If you own property in the affected area, you need to begin flood mitigation efforts, whatever those efforts may be for your individual building or home. It could be relocation, it could be moving to higher ground or it could be simply sandbags,” Cedar Rapids Mayor Ron Corbett said at a news conference Thursday afternoon. “The city is taking this event very seriously, and we’re putting in plans today. Citizens, property owners need to do the same.

“We have four days to get ready, and now is the time to start."

Water will reach the downtown core, the NewBo district and the Czech Village and Time Check neighborhoods if levels actually hit 24 feet, city officials said. Public Works crews were out Thursday plugging sewers, preparing pumps and identifying areas to sandbag. Pre-emptive road closures are expected Saturday.

City Manager Jeff Pomeranz called the event “potentially significant.” Officials warned residents to stay alert and prepare to evacuate if needed.

The city is expected to make decisions about whether to evacuate low-lying areas Sunday morning.

“While no one knows exactly what is going to happen, we believe that communication and caution, preparation and response is absolutely critical in an event such as is being predicted,” Pomeranz said.

The city plans a 10 a.m. news conference every day through Tuesday to provide updates on its preparation plans. Updates also will be posted on the city’s website.

Upstream, the Cedar River upstream at Cedar Falls and Waterloo is expected to crest at its second-highest levels ever during the weekend.

The National Weather Service expects it to crest 9½ feet above flood stage in Cedar Falls on Saturday afternoon, barring no more rain. The river crested 14.1 feet above flood stage in 2008. It could reach 22 feet by Saturday night in Waterloo. That's 9 feet above flood stage. The Cedar River reached 27 feet in Waterloo eight years ago.

Those projections could change as more rain was expected Thursday night in northeast Iowa. The National Weather Service was predicting half an inch to an inch of rain overnight, with the potential for localized rainfall reaching up to 4 inches.

"We're not expecting quite the amount we saw last night, but still the potential for significant rainfall," according to the weather briefing.

Black Hawk County Emergency Management Coordinator Lorie Glover said the river is already out of its banks at some spots in Waterloo. Many areas along the floodplain were part of a buyout following the 2008 flood, and other homes in the area have been elevated, she said. The levee system in Waterloo can hold water levels up to 30 feet, she said.

Storm sewers there will close when the Cedar River reaches 17 feet, and some bridges will close at 24 feet. The river was at 10 feet at 6 p.m. Thursday, a full 3 feet below flood levels.

Emergency personnel are preparing to address flooding by moving pumps and testing gates. They are in constant communication with law enforcement, non-profit agencies such as the American Red Cross and local hospitals, Glover said.

She asked residents to be alert and prepare for evacuation if needed.

Flooding is not expected farther south in Iowa City and Coralville — two communities that suffered extensive damage in 2008.

Dee Goldman, the Army Corps of Engineers' operations project manager at Coralville Lake, said engineers are releasing water from the dam at the maximum level of 6,000 cubic feet per second to mitigate moderate flooding in Marengo.

The river downstream of the dam should remain within its banks, Goldman said.

The Army Corps plans to reduce output from the dam to 1,000 cubic feet per second Tuesday as floodwaters make their way south along the Cedar River to avoid worse flooding to the south, where the Cedar River meets the Iowa River at Columbus Junction.

Flooding upstream

About 50 miles upstream, law enforcement reported widespread flooding across Butler and Bremer counties, with several county roads closed because of high water.

Butler County Sheriff Jason Johnson said emergency personnel rescued residents from six homes overnight Thursday in Greene, a town of about 1,100 on the Shell Rock River. Residents from about 80 homes were moved to higher ground during the day, he said.

Some city streets were covered with up to 2 feet of water and at least two homes had to be reached by boat, Johnson said. The river was expected to crest at 20 feet Thursday night, a mark below 2008 levels.

No injuries were reported, Johnson said.

"Everyone is in good shape," he said. "A lot of them have been through this before, and they've been making preparations all night."

Gov. Terry Branstad verbally declared a disaster proclamation for Butler, Chickasaw and Floyd counties. Additional counties are expected to be added to a formal proclamation in the days ahead, according to a news release from the governor's office.

"We anticipate extensive flooding along the Cedar River eventually affecting Cedar Rapids," Lt. Gov. Kim Reynolds said in the release. The state has provided 30,000 sandbags and deployed eight water pumps to affected counties.

Volunteers and emergency responders started flood operations in Greene on Wednesday night, said Jeff Stirling, a volunteer with the local ambulance service. He and many others had been working overnight to fill sandbags and help protect their community, he told a reporter Thursday afternoon.

Residents stopped by the site where Stirling was working to pick up sandbags for their homes. Walls of sandbags also were built on East Traer Street, near Second Street and First Street.

Marilyn Wahlgren, who lives on North Grove Street, took sandbags to her house even though it’s on high ground. She said her basement flooded, because water from the heavy rains had saturated the soil around the home she has owned for 25 years.

Mark Nelson, of Marion, traveled to his hometown of Greene to help with the sandbag operations.

“You've got to save your hometown,” he said. “I was raised here. My children and grandchildren still come here to visit their grandmother and great-grandmother, and I just want to make sure that it's here for another 100 years. That's what we do. We just get together as a community."

The North Butler school district canceled classes Thursday and Friday. The high school is being used as an emergency shelter. Cedar Rapids Xavier planned to let students out of school at 11 a.m. Friday to help with sandbagging efforts there.

The National Weather Service said the Greene fire department reported 7½ inches of rain just before 11 p.m. Wednesday. The service also said a tornado reported to have touched down briefly 4 miles west of Greene had not been confirmed.

Travel into Greene was restricted to local traffic only. Operations were hampered by people coming to town to observe the flooding, Johnson said. Anyone who wishes to volunteer in the future can call 319-267-9968. They will be put on a list and contacted as needed, he said.

In Mason City, where residents were evacuated from two apartment complexes, more than 2½ inches of rain fell over 12 hours. The Winnebago River was expected to crest 4 feet above flood stage at 14.2 feet early Friday morning, depending on rainfall upstream and in the area.

Mason City authorities asked residents in low-lying areas to plan for evacuations and move their vehicles to higher ground.

The National Weather Service also reported flooding in Hawkeye, Charles City and Lansing, where mudslides were bringing trees on to highways. Charles City received about 4.8 inches of rain, and one measuring station south of Nora Springs recorded 9.36 inches, the service said.

— The Associated Press contributed to this report.

Cedar and Shell Rock river forecasts

Shell Rock: Shell Rock River expected to crest at 18.1 feet by 1 p.m. Friday. Record is 20.36 in 2008.

Cedar Falls: Cedar River expected to crest at 97.5 feet by 1 p.m. Saturday. Record is 102.10 feet in 2008.

Waterloo: Cedar River expected to crest at 22 feet by 7 p.m. Saturday. Record is 27.01 feet in 2008.

Cedar Rapids: Cedar River expected to crest at 24.1 feet by 1 a.m. Tuesday. Record is 31.12 feet in 2008.

*National Weather Service river forecasts as of 7 p.m. Thursday. Crest levels and times subject to change. Visit water.weather.gov for up-to-date forecasts.

One injured in accident

A pedestrian who was trying to direct traffic around flood waters in Rockwell was struck by an oncoming vehicle. The Cerro Gordo County Sheriff's Office reports 34-year-old Mark Nel of Nora Springs was taken to the hospital with injuries.

The driver, 70-year-old Merlyn Tramel of Rockwell, was cited for unsafe approach to a stationary vehicle resulting in injury.