A northern stretch of the Illinois River, a main artery for shipping bulk commodities to export terminals at the Gulf of Mexico, is expected to remain closed for several weeks as the U.S. Army Corps of Engineers works to repair a lock damaged during recent heavy flooding.

Severe flooding on the waterway has also halted the loading of corn and soybean barges at terminals along the waterway and delivery points for CME grain futures contracts, with the exchange declaring force majeure on Thursday at all terminals it uses on the river.

Barge owners also pulled their Illinois freight offers for the remainder of this week and next as shipping is halted, given the record flooding that occurred last week when torrential rains moved through the upper Midwest.

"The Coast Guard has declared it unnavigable so even if you wanted to move something you'd need to get clearance from the Coast Guard right now," an Illinois River barge broker said.

"People might be able to start loading next week on the northern half of the river if they have a barge on station, but the crest on the southern half is expected to linger a bit longer and that might bring you to the end of next week," he said.

About 60 percent of U.S. grain exports are transported via the Mississippi River and its tributaries, including the Illinois, from farm areas in the Midwest to export facilities at the Gulf of Mexico. The Illinois River disruptions considerably restrict the flow of grain from much of the No. 2 corn and soybean producing state.

Grain export premiums at Gulf of Mexico terminals climbed this week to the highest level in at least a month as the closures severed the supply pipeline upon which exporters rely. If corn and soybean exports were not currently struggling to compete with massive South American shipments, prices would likely have rallied even higher, grain traders said.

Lock Damage

The damage to the Marseilles Lock and Dam in northern Illinois suggests a portion of the waterway may remain closed well after flood waters recede.

"As soon as conditions permit, the Corps will perform engineering analyses for use in developing repair and recovery plans, ensuring that the dam can be returned to an operational status as soon as possible," said Tom Heinold, deputy chief of the Operations Division for the Corps' Rock Island district.

Five of the lock's eight gates, damaged last week when seven barges broke free from a tow in flood-swollen currents and struck the dam, are not able to close fully and maintain the pool of water above the dam. Two of the gates have 15- to 20-foot holes.

As a result, the section of the river from Marseilles to the Dresden Island lock upriver was expected to drain and become too shallow for barges and boats as soon as this weekend, the Army Corps said.

"Probably beginning next week we're going to start emergency repair work to get a rock dike out there and get work started on those gates to get them functioning to at least maintain the pool," said Army Corps spokesman Ron Fournier.

"How much of the pool we're going to lose is not determined yet, but we're not going to be able to maintain the nine-foot depth pool," he said.

A 144-mile stretch of the waterway from mile marker 43.2 south of Florence, Illinois, to mile marker 187.3 near Lacon, Illinois, remains closed to all traffic due to record flooding, the U.S. Coast Guard said on Thursday.

Eight locks on the Mississippi River from central Iowa just north of St. Louis remain closed due to high water, but the river has largely crested and all locks were likely to reopen by early next week.

The shipping disruptions come just three months after record- or near-record-low water on the Mississippi River threatened to halt navigation along a key stretch between St. Louis and the confluence of the Ohio River. (Reuters)