Rising flood waters were expected to make 11 locks and dams impassable on the mid- and upper-Mississippi River and force the closure of the river later on Monday from Bellevue, Iowa, to Saverton, Missouri, the U.S. Army Corps of Engineers said.
The closure would be the most extensive since 2008 on that stretch of the country's busiest waterway, said Ron Fournier, public affairs officer for the Army Corps' Rock Island district. At least 80 barge tows are expected to be affected by the closure.
The Mississippi River is the main shipping route to the U.S. Gulf Coast, where about 60 percent of all U.S. corn, soybeans and wheat exports exit the country.
Near-record rains caused extensive flooding last week in parts of Minnesota, Iowa and the Dakotas. The rising waters prompted lock closures at the Twin Cities of Minneapolis and St. Paul, which prevented barges from being loaded and slowed the transportation of grain and scrap metal.
The fast-moving waters are now causing problems downriver, and will likely force closure of 11 of 12 Mississippi River locks in the Rock Island district, Fournier said.
"The river levels will increase where the river goes over the miter gates and that makes them inoperable. This new water that's coming could cause some problems," Fournier said.
There was no estimate for when the locks would be reopened, he said.
A storm system moving across eastern Iowa and southern Minnesota could dump 2 inches (5 cm) of rain on Monday. This is already the wettest June in the Twin Cities since 1874, according to the National Weather Service.
The Mississippi River at Rock Island, Illinois, was in the moderate flood stage of 17 feet and was expected to hit the major flood state of 21.8 feed by Saturday, the weather service said.
Barge loadings could be delayed for seven to 10 days, a shipping source said.
(Additional reporting by Karl Plume in Chicago; Editing by Chris Reese, Toni Reinhold)