LODGE GRASS, Mont. — Rain-swollen rivers that have swamped Montana towns could keep flooding the region for another month or more as melting mountain snow delivers a second slug of water to the soggy Northern Plains.
Heavy rains are forecast through the holiday weekend. Warm weather after that is expected to kick off the melt of high-elevation snows that are much deeper than average.
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In neighboring Idaho, Gov. Butch Otter declared an amergency due to flooding. High water in central Idaho is blamed for the disappearance and likely death of a woman who authorities said was swept into the Salmon River on Wednesday.
And Wyoming directed its National Guard to deploy troops to help counties facing high water.
Even with rivers running wildly from record rainfalls, agencies have started dumping massive volumes of water from low-land reservoirs to get ready for the annual spring melt. That's predicted to flood homes downstream in the Dakotas, and possibly in Iowa, Nebraska, Kansas and Missouri as well.
"There is going to be record flooding all along the Missouri River," said Paul Johnson, director of the Douglas County, Neb., Emergency Management Agency. "This isn't going to return to normal anytime soon."
In Montana, the state's famous rivers and streams — swollen to several times their usual size in places — continued to carry a torrent of debris and damage through small towns and over roads Friday as emergency officials brought in reinforcements and the governor toured the hardest-hit areas.
Mountain peaks were packed with up to twice as much melting snow as usual. And more rain was forecast for a Memorial Day weekend that will to be hard on travellers: Dozens of roads and highways were closed around the state as cresting waters broke through barriers and filled many homes with muddy floodwater.
Officials warned that dozens of campgrounds and fishing access sites also would be closed.
"We are going to be in floods not just here but all over Montana for the next 30 days," Gov. Brian Schweitzer said after a helicopter tour of the waterlogged Crow Indian Reservation south of Billings.
"Things suck, that's the most polite way I can say it," Jeff Gates, the area's disaster and emergency services coordinator said on Friday.
The U.S. Army Corps of Engineers said it had no choice but to continue record releases from brimming reservoirs. Dams built decades ago to contain dangerous floodwaters were now being used to release a carefully controlled torrent.Video: Teen rescued from rising floodwaters (on this page)
In Missouri and Nebraska, the river was already spilling over its banks and soaking low-lying farmland. More flooding was predicted as releases from swollen upstream reservoirs were expected to reach "historic" levels, officials said.
"We have gotten about a year's worth of rain in Montana in the last month," said Monique Farmer, spokeswoman for the corps' Omaha, Neb., district. "It's just crazy. It's been an unusual year."
Officials said water is encroaching on cities such as Fort Calhoun, Neb., and Sloan, Iowa — where residents built a temporary levee out of sandbags to help protect a dozen homes near the river.
The Army Corps of Engineers predicted 2011 could be one of the wettest years on record in the Missouri River basin. The agency has predicted flooding into July.
South Dakota officials decided to build emergency earthen levees on each side of the Missouri River in an attempt to protect homes in Pierre and Fort Pierre from floodwaters.
But South Dakota Gov. Dennis Daugaard said waters expected to increase again Saturday with more releases from dams will flood some homes before work on the levee system can begin
"We believe the levee construction is certainly very good news, but some areas will be inundated even as the levees are being constructed," Daugaard said.
In Wyoming, Gov. Matt Mead said Friday he was deploying more than 100 Wyoming National Guard soldiers as more snow was predicted to fall this weekend and the state's huge mountain snowpack was expected to begin melting in earnest next week. Five teams of soldiers will be available next week, and three counties have already requested Guard help.
Unseasonably cool weather could bring a small amount of respite in Montana over the holiday weekend by slowing the melting mountain snows. But Montana Disaster and Emergency Services Division chief Ed Tinsley warned the reprieve could be brief.
Weather officials said another 1 to 2 inches of rain was forecast over the weekend for eastern Montana. May has already seen over 5 inches of rain in Glasgow — a place accustomed to not much more than an inch for the entire month.Video: Floodwaters force animals out of Dakota zoo (on this page)
The additional precipitation could cause the Milk River in northern Montana to rise another foot, putting it 6 feet beyond flood levels, said Bill Martin, National Weather Service meteorologist.
The Montana Department of Fish, Wildlife and Parks warned anxious anglers that the state's blue-ribbon trout streams are now carrying "all manner of dangerous debris." The agency closed access to the rivers in many places and warned those who try to brave the floodwaters to be prepared.
Schweitzer and U.S. Sen. Jon Tester toured waterlogged communities to gauge the damage from flooding that has spread across the state. Several dozen homes in the central Montana town of Roundup remained underwater.
A 170-mile stretch of U.S. 12 from Harlowton to Forsyth was closed Friday morning, state Transportation Department officials said. Roundup emergency services said the closure cut off road access to the town from the west and east. The only way into Roundup by road was from the north because U.S. 87 south of town also was shut down, officials said.
On the Crow Reservation, officials have tallied 200 damaged homes and that figure is expected to rise, Chairman Cedric Black Eagle said. Also damaged by the high waters were irrigation systems, roads, bridges and other infrastructure.
"It will be six months to a year before things are back to normal," Black Eagle said.
About 300 reservation residents fled north to Billings to take temporary refuge on a college campus where the Red Cross had set up a shelter in a residence hall. Crews were working Friday to restore full pressure to the reservation's water supply.
Montana's governor also planned to travel north to Lewistown, where floodwater had swamped parts of town and forced road closures.
The state was expecting help from the Federal Emergency Management Agency by next week.
The Associated Press and Reuters contributed to this report.