KANSAS CITY, Mo. —It isn't so much the amount of water churning its way down the Missouri River that has people along the nation's longest waterway on edge. It's how long all that water will stick around.
The annual "spring rise" on the Missouri will last deep into this soggy summer, as a torrent of early season rains and winter snowpack flows through wide-open gates of South Dakota's Gavins Point Dam upriver and toward the confluence with the Mississippi River. The Missouri might start to crest soon, but it won't start to fall until August or later.
That constant pressure on the network of levees that protect farmland, roads, small towns and big cities from a river running well outside its banks is what worries folks downriver most as the high water heads south toward Kansas City and east toward St. Louis.
"The length of the flood will test levees like they've never been tested before," Missouri Gov. Jay Nixon said. "You're going to see levees which in essence may be tall enough, but not strong enough."
That isn't the only worry as the summer of 2011 shapes up as the worst since 1993, when the Missouri River swollen by weeks of rain over the north-central United States led to flooding that killed 32 people, damaged an estimated 100,000 homes and caused $15 billion in damage.
There's also the prospect of flooded fields in five states that will keep farmers from planting some crops and harvesting others. Highways covered with river water will be as much a headache for drivers as the cash-strapped states and counties that must pay to fix them. Barge operators — and those who rely on them — face big losses if the river remains closed to navigation.
And then there is the greatest unknown in a river valley with no more room for any more water.
"One of my biggest concerns is simply rain," Nixon said.
The Missouri was already running higher than normal last fall, when rains upriver combined with a heavy winter snow to fill the reservoirs in South Dakota and Montana and force the record-setting releases from dams the Army Corps of Engineers uses in most years to control the river's flow.