MINNEAPOLIS (Reuters) - South Dakota appealed for bulldozers and operators and called up 200 more National Guard troops on Sunday in a race to finish levees before heavy Missouri River flows reach the capital, officials said.

The U.S. government plans to step up releases from several dams along the Missouri River in early June to relieve pressure on reservoirs swollen by heavy rains and melting winter snowcaps from Montana through North and South Dakota.

South Dakota Governor Dennis Daugaard on Sunday said he would call up additional troops and sought bulldozers and operators to support construction crews, but urged residents of Pierre and Fort Pierre to be prepared for the worst.

"While we will work urgently around the clock to get these levees constructed, individuals must assume the worst, that the levees may not be completed in time and if completed they may not hold," Daugaard said.

The U.S. Army Corps of Engineers increased flows from the Oahe Dam upstream from Pierre Saturday to relieve pressure and will hold that level until Friday, the day after additions to the levees are due to be finished.

"The contractor is working urgently to complete these levees, but the increased flow requirement means that the job has suddenly been enlarged within the same time frame, which was already a difficult time frame," Daugaard said.

Daugaard suspended commercial truck driver licensing requirements and appealed to farmers and ranchers with experience operating heavy machinery to fight flooding.

"I want to use their talents where we can," he said.

The Corps expects to reach maximum flows from the dams by about mid June and hopes to hold a two-foot buffer on the levees around the capital. Some residents are not protected by levees under construction.

Hundreds of residents in both Pierre and Fort Pierre are expected to be affected by the rise in the Missouri River as the flows increase, the mayors of the cities said on Sunday.

Rain overnight through to Sunday morning likely did not add to the Missouri River heights, but created a nuisance factor for those building clay levees, officials said.

Drinking water has been protected and steps have been taken to protect the sewage treatment plant, Pierre Mayor Laurie Gill said on Sunday.

Daugaard, meanwhile, has pressed for better maps of potential flooding downstream so residents of Yankton and other towns will have better information to plan evacuations.

On Saturday, Daugaard urged Yankton residents to plan for possible evacuations. Yankton is a city of about 14,500 residents in southeast South Dakota along the Nebraska border. He urged the same for the 2,500 residents of Dakota Dunes.

"Property owners in Yankton and Dakota Dunes should plan for the worst," he said Sunday. "Move property out, now."

Prison inmates have been sent to the downstream communities to bag sand in advance of peak flows expected in coming weeks.

Officials in the states of Idaho, Montana, Wyoming and North Dakota also are amassing emergency assistance to fight flooding, including calling up National Guard troops.

About 1,500 North Dakota National Guard troops have been mobilized to fight flooding along the Missouri River that threatens the state capital of Bismarck and nearby Mandan as the flow from the Garrison Dam is increased.

Bismarck city officials said they needed volunteers to fill more than 4 million sandbags by Thursday to fight the flooding. The Corps has also hired contractors to build more than 5 miles of temporary levees to reduce flooding in Bismarck.

Tributaries of the Columbia River have breached their banks in eastern and northern parts of Idaho, forcing the governor to declare a state of emergency.

High water in the Columbia and Missouri follows major flooding of the Mississippi in the Midwest and South this year. The Missouri flows into the Mississippi, compounding flooding fears in the downstream states of Iowa, Nebraska and Missouri.

(Reporting by David Bailey in Minneapolis and Laura Zuckerman in Idaho; Editing by Jerry Norton)

Source: Reuters US Online Report Domestic News