Evacuations are already underway in low-lying areas of western Iowa and eastern Nebraska as the Missouri River rises. Water levels are expected to hit record highs with huge snowpacks melting up stream and water gushing from reservoirs. Nebraska Governor Dave Heineman took an aerial tour along many miles of the Missouri on Tuesday and says it appears the region is in for a long-lasting disaster.

“This is going to be a 100-year, 500-year flood, there’s no question about it,” Heineman says. “I’m very concerned it’s going to be a very serious situation that we’re going to face, along with our neighbors in Iowa and South Dakota. In most of our lifetimes, this is going to be the largest and potentially the most devastating flood that we’re ever going to see.”

Heineman met with leaders in several communities along the swollen Missouri River. The governor says, “The big concern I think I heard all day long is how much more water is going to occur and flow down the Missouri River over the next two weeks?”

Forecasters say the already-high waterway will continue to rise into mid-June, cresting perhaps seven feet over flood stage in many areas. Some fear the flooding will persist well into July.