OMAHA, Neb. — When the Missouri River's floodwaters recede this fall, piles of debris, silt and some smelly surprises will be revealed.
It's hard to say exactly what's hiding under the waters, but experts said it is certain that this year's epic flood will leave behind a mammoth mess once the water returns to within the Missouri River's banks.
"It's a very unpleasant chore for people trying to clean this up," said John Remus, who oversees hydrologic engineering for the Army Corps of Engineers' Omaha office.
The corps has been releasing massive amounts of water from the dams along the Missouri River all summer to deal with above-average Rocky Mountain snowpack and unexpectedly heavy spring rains. The huge amount of water flowing down the river caused flooding all along the Missouri that began in June and will continue into fall.
Many of the hundreds of thousands of acres the river flooded in Iowa, Nebraska and Missouri this year were farmland, so the mess is certain to include agricultural debris like crops, fuel tanks, branches and miscellaneous equipment.
"We know that there's going to be damage up and down the river, but the degree of damage is likely to vary considerably," said David Haldeman, a division administrator with the Nebraska Department of Environmental Quality.
Haldeman said the fact that most people had a couple weeks' notice before the floodwaters arrived in the spring might reduce the number of propane tanks, gas cans and other floating debris that got swept away.
Carcasses of small animals swept up by the flood and fish left behind when the waters recede will add to the mess.
"A very bad odor gets started very quickly," said Kathy Lee, a spokeswoman for the Iowa Department of Natural Resources.
At the height of the flooding, there were reports of camping trailers, decks, 60-foot-tall trees and other large debris being swept away by the river. And the flood swept through a number of cabin developments north of Omaha and some rural houses, so almost anything found in a home could wind up in the flood.
"You can find about anything under the sun after flooding," Lee said.
There will be piles of sand left behind because the rushing water picked up deposits from the river bed and carried it onto the floodplain. And anywhere where the river broke through a levee, the amount of sand will be increased because many rural levees are made of sand.
"The main thing you're going to find under the water is sand," Remus said.
Farmers will have to scrape the sand away to reach the topsoil before they consider planting on the land again. And Remus said in some cases, it may not make economic sense to do that, depending on the thickness of the sand layer and the quality of the farmland.
"I think most of it will be able to be rehabbed," Remus said.
The corps has begun gradually reducing the amount of water being released from the dams, but it's a long process. So people who live near the river in Iowa, Nebraska and Missouri will have to wait until sometime in September or October for the floodwaters to return to the riverbanks.
Officials predict the river will fall below flood stage in the Sioux City, Iowa, area in late August. Near Omaha, the river will fall below flood stage by mid-September, and the flooding near Rulo, Neb. and Hamburg, Iowa, should end by late September.
Flooding along the river in Missouri may not end until around mid-October because several levees failed in the northwest corner of the state and allowed a large amount of floodwater to accumulate.
The length of this year's flood will make the cleanup harder.
"It won't give us much time for recovery before frost and winter sets in," Lee said.