By David Hendee
OMAHA, Neb (Reuters) - Drivers trying to cross from southeast Nebraska into Missouri and Iowa on Monday found bridges closed for more than 100 miles for safety reasons due to flooding and heavier water flows on the Missouri River.
Authorities said water flowing over two levees in northwest Missouri's Holt and Atchison counties on Sunday closed U.S. Highways 159 and 136 in western Missouri, affecting bridge crossings at Rulo and Brownville in southeastern Nebraska.
With those closings, flooding has shut down all road bridges over the Missouri River for about 112 miles from just south of Omaha, Nebraska, to St. Joseph, Missouri. The Nebraska Highway 2 bridge at Nebraska City, Nebraska, closed earlier.
More bridges and railroad lines may have to close as the water continues to rise, officials said.
"We've never experienced anything like this," Iowa Department of Transportation spokeswoman Dena Gray-Fisher said.
Heavy rains and snow melt along the Missouri River valley have flooded areas from Montana through Missouri, forcing residents to shore up protections and evacuate their homes.
The bridge closures coincided with stepped-up releases of water from swollen reservoirs from Montana to South Dakota by the U.S. Army Corps of Engineers, which is managing record flood waters this season in the Plains.
The Corps boosted water releases over the weekend from two dams -- Oahe above Pierre, South Dakota's capital, and Big Bend Dam just downstream from that -- to make room for more flows expected with potentially heavy rains.
A toll bridge from Onawa, Iowa, to Decatur, Nebraska, may close, Gray-Fisher said. Other vulnerable bridges include one on U.S. 30 between Missouri Valley, Iowa, and Blair, Nebraska, and at U.S. 34 between Interstate 29 and Plattsmouth.
Union Pacific and Burlington Northern Santa Fe railroad tracks have been raised in some areas to escape flooding, according to company officials.
Some track sections are closed. Flooding may close a Union Pacific line between Omaha and Kansas City, Kansas at Atchison, Kansas this week, railroad spokesman Mark Davis said.
In North Dakota, residents braced as Garrison Dam above the state capital at Bismarck released what is expected to be a sustained peak flow of 150,000 cubic feet per second.
"This 72 hours that we are in right now with the 150,000 cubic feet per second is probably the most critical period," Bismarck Mayor John Warford told reporters on Monday morning.
Peak releases are planned until at least mid-August and high flows are expected until December.
Extensive heavy rains of up to 2 inches are possible from western and central Nebraska through central and eastern South Dakota adding to stress in the Missouri River basin.
Rain totals of 3 inches to 4 inches are likely in some spots with 5 inch-plus rains possible, Bruce Terry, a National Weather Service forecaster, told reporters.
The weather service also expects up to 3 inches of rain in central and western North Dakota over the next two days, with lesser amounts in far western North Dakota and eastern Montana, meteorologist Lisa Schmit told reporters.
Breaches of levees in Missouri decreased flooding near Hamburg, Iowa, on Monday. Fire Chief Dan Sturm said Hamburg was using the reprieve to bolster its secondary levee.
In South Dakota, Pierre resident Emily Wickstrom said the levees were still holding, although an affluent neighborhood in Fort Pierre was evacuated.
"I think everybody figures it's a hurry up and wait," Wickstrom said. "It is kind of scary, though, to watch the water creep up."
Flash flooding from heavy rains overnight also caused problems in areas away from the Missouri River.
Three miners were trapped by high water in an underground coal mine in southeastern Kentucky Monday. A state official said it is expected they will be rescued this afternoon.
Along the Illinois River, a levee in Scott County, Illinois was breached in three places, flooding farmland but posing no threat to people, Corps spokesman Mike Petersen said.
(Additional reporting by David Bailey in Minneapolis; Michael Avok in Omaha, Bruce Olson in St. Louis, and Kevin Murphy in Kansas City; Editing by Mary Wisniewski and Greg McCune)