(Adds Mississippi River reopening near St. Louis, adds grain prices rising)
By Karl Plume
April 22 (Reuters) - Commercial shipping traffic was moving again on the Mississippi River south of St. Louis after a pair of barge accidents that forced the U.S. Coast Guard to close the waterway over the weekend, but navigation remained severely impaired further north.
Flooding following torrential rains across the central United States forced the U.S. Army Corps of Engineers to close about a dozen locks on the Illinois River and the Mississippi River north of St. Louis late last week.
The U.S. Coast Guard will also close a section of the Illinois River near Peoria to all traffic later on Monday to protect levees, and was considering shipping restrictions in other areas as heavy currents made navigation treacherous.
The shipping headaches come just three months after near-record-low water threatened to close the Mississippi River along a busy stretch from St. Louis to its confluence with the Ohio River at Cairo, Illinois.
"While the conditions are much different than they were this winter, the effects are quite the same. We're placing operational guidelines on the vessel industry and shutting parts of the river," said Coast Guard spokesman Colin Fogarty.
A 15-mile stretch of the Mississippi River near St. Louis was closed late Saturday after 114 barges primarily owned by American Commercial Lines (ACL) broke free from a fleeting area and 11 of them, all containing coal, sank.
All of the barges were secured and an aerial survey on Monday found that none of the sunken barges posed a risk to navigation. The Coast Guard, U.S. Army Corps of Engineers and ACL were coordinating plans to remove the sunken barges.
"Two of the barges were just barely outside the channel so we were able to allow navigation by them. There was also one barge that sunk in the middle of the channel, but it is currently under about 20 feet of water so it doesn't pose a threat," Fogarty said.
A queue of at least four upriver vessels and four downriver vessels towing 79 barges formed during the 36-hour closure and should be cleared quickly as the river was open to two-way traffic.
Another barge accident further south near Vicksburg, Mississippi, shuttered the river Sunday morning between mile markers 415 and 436 before one-way traffic was allowed to resume early on Monday.
Three grain barges and 27 coal barges had broken free of a barge tow. One sank and at least one struck a railroad bridge, the Coast Guard said.
When the river reopened to southbound traffic, 12 vessels pushing about 120 barges were awaiting passage. A northbound queue of 16 vessels pushing about 230 barges would be cleared through the area once the southbound queue had passed, the Coast Guard said.
The Army Corps shuttered about a dozen locks on the Illinois and Mississippi rivers late last week and over the weekend due to high water, but most could reopen by the end of April or early May, according to the latest river crest forecasts from the National Weather Service.
Grain export prices climbed as the shipping disruptions, expected to persist to some degree for at least another week, severed the farm-to-port supply pipeline for shippers at the Gulf of Mexico.
Some 60 percent of U.S. grain exports are shipped via the Mississippi River system from production areas in the Midwest to export terminals at the Gulf of Mexico. Various other commodities, including oil, coal and fertilizer are also shipped on the inland waterway system.
Spot corn prices at the Gulf rose to the highest in a month while soybean prices hit a three-month high as exporters scrambled for needed supplies.
(Reporting by Karl Plume in Chicago; Editing by Dan Grebler and Jim Marshall)