PIERRE, S.D. (AP) — Crews raced approaching floodwaters Tuesday to complete emergency levees aimed at protecting South Dakota's capital city and two other towns as the swollen Missouri River rolled downstream from the Northern Plains. Meanwhile, the mayor of Minot, N.D., ordered a quarter of the city's residents to evacuate areas along the flooding Souris River.
Residents of the upscale community of Dakota Dunes in southeastern South Dakota, below the final dam on the river, have been told to move their possessions to higher ground and be ready to leave their homes by Thursday, a day before releases from the dams are set to increase again.
Several thousand people in Pierre, the state capital, and neighboring Fort Pierre on the west bank have been working day and night since late last week to lay sandbags around their homes and move to safety.
Those forced to leave their homes may not be able to return for two months or more. No evacuation orders had been issued Tuesday in South Dakota, but many people in the three cities had already moved to safer places.
"We're going to fight this flood with every fiber of our beings, and we'll do everything we can to minimize its effects," Gov. Dennis Daugaard said.
In Minot, N.D., Mayor Curt Zimbelman said the evacuation order affects about 10,000 residents who live along a 4-mile stretch of the Souris, which has risen with rain, snowmelt and discharges from Lake Darling. Zimbelman said residents are expected be out of their homes by Wednesday night, in part to give construction crews room to raise and reinforce earthen dikes in the area. The Souris is part of a different river system than the Missouri.
The U.S. Army Corps of Engineers is increasing releases from the six dams on the Missouri River to drain water from record rains of up to 8 inches that fell in eastern Montana and Wyoming and western North Dakota and South Dakota in the past two weeks. Heavy runoff from melting snow in the northern Rocky Mountains is expected to add to the problem soon.
Flooding in Montana has damaged at least 200 homes on the Crow Indian Reservation and many more homes and businesses in other areas. Water levels had dropped more than 2 feet in the central Montana town of Roundup, but warmer weather later in the week is expected to cause a new round of flooding in parts of the state as mountain snows melt.
In North Dakota, more than seven miles of levees were being built in Bismarck and another 3 1/2 miles were going up across the river in Mandan.
A minimum-security state prison on the Missouri's east bank just south of Bismarck was evacuated, North Dakota corrections officials said Tuesday. About 140 inmates from the Missouri River Correctional Center were moved Monday to a juvenile detention center in Mandan, but officials said they will be housed away from the center's teenagers.
Officials in western Iowa, downstream from Dakota Dunes, were making plans to deal with flooding in Sioux City and other areas. The Nebraska towns of Niobrara and Santee are already dealing with flooding from the Lewis and Clark Reservoir, while cities further downstream are preparing for high water over the next month.
In the three South Dakota cities, streets were busy with National Guard trucks, pickups carrying sandbags and large trucks carrying clay to build the levees. Many homes had already been surrounded with walls of sandbags that were up to 6-foot high.
Daugaard said the earthen levees were being built to 2 feet above the expected crest in all three towns, but he urged residents not to count on the levees to protect them.
"Citizens should assume the worst, that we will be unsuccessful in getting the levees raised in time or that the levees once raised will not hold," the governor said.
He said no deaths had been reported from flooding, and for now, the concern is about saving property.
"In the end, we must remember these things are just things," Daugaard said.
Water levels are expected to rise by 8 feet in the Dakota Dunes area by June 14, when releases from Gavins Point Dam are expected to peak at 150,000 cubic feet a second, about double the current flow, Paul Boyd of the Corps of Engineers said.
Daugaard said nearly all of Dakota Dunes, a city of about 2,500, would be subject to flooding if the levee system does not hold.
Jeff Dooley, city manager, said Dakota Dunes planned to shut down its water treatment plant and connect to Sioux City, Iowa's water system.
Russ Riesen said he and his wife had already moved most of their possessions to an apartment they rented in nearby Sioux City.
"We're going to sit it out up in the hills and hope everything works out," Riesen said. "With Mother Nature, you never know what's going to come."
Dakota Dunes, an upscale planned community established in 1990 in the extreme southeastern tip of South Dakota, is home to a number of companies. It was founded after computer maker Gateway started operations in the area, but the company later moved to California.
Water levels are predicted to rise about 4 feet in Pierre and Fort Pierre, where about 2,000 people in Pierre and several hundred more in Fort Pierre could be affected. Water has already reached some houses in Fort Pierre, and levees are expected to be completed before Friday morning, when releases are next increased from Oahe Dam.
Daugaard said a small residential area in Yankton, upstream from Dakota Dunes, was expected to flood, but little flood damage was expected on the Lower Brule and Crow Creek Indian reservations in central South Dakota.
Associated Press writers James MacPherson and Dale Wetzel in Bismarck, N.D., Josh Funk in Omaha, Neb., and Grant Schulte in Niobrara, Neb., contributed to this report.