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Why Is the Missouri River Overflowing?

The Missouri River on June 4, 2011. (Image credit: NASA Earth Observatory.)

A massive snowpack, historic rainfall and more wet weather in the forecast are the triple whammy causing waters to swell along the Missouri River and its tributaries.

The huge amount of water will force the U.S. Army Corps of Engineers to release more water than ever from the river's reservoir system, officials said today (June 6).

Experts said that unusually wet weather has led to significant amounts of water in the Missouri River basin, especially in the upper reaches. The river's two largest reservoirs saw record amounts of inflow in May, and several more inches of rain are forecast in the upper reaches of the basin over the next few days.

To combat the rising water, the corps is planning water releases at up to 150,000 cubic feet per second from the river's reservoirs in the coming days, an unprecedented rate.

"We're going to be releasing more water than we've ever released before," said Kevin Grode of the U.S. Army Corps of Engineers.

To add to the flooding problem, forecasters see the "potential for really significant rainfall in that area," possibly up to 2.5 inches (6.4 centimeters) in Montana and northern North Dakota, said Lynn Maximuk of the National Weather Service. Heavy rain could also hit near Omaha, Neb.

If that happens, the Missouri River flooding could at least rival the current flooding on the Mississippi River , Grode said.

The corps may be forced to continue releasing water until mid-August, since this year's snowpack 140 percent of normal hasn't fully melted.

"At this point we have yet to see the mountain snowpack come off," Grode said.

A La Niña pattern caused the usually big snowpack and the rainfall in the region (and this year's violent tornado season , too), Maximuk said.

Richard Serino, of the Federal Emergency Management Agency, said that people living along the river should pay close attention to their local officials and television and radio warnings for the best information on flooding near their towns.

Mightiest Floods of the Mississippi River

Reach OurAmazingPlanet staff writer Brett Israel at bisrael@techmedianetwork.com. Follow him on Twitter @btisrael.

Brett Israel was a staff writer for Live Science with a focus on environmental issues. He holds a bachelor’s degree in biochemistry and molecular biology from The University of Georgia, a master’s degree in journalism from New York University, and has studied doctorate-level biochemistry at Emory University.