LOS ANGELES (MarketWatch) — A section of the Mississippi River has been closed indefinitely due to high waters, hindering commercial traffic along the critical waterway, Coast Guard officials said Tuesday.

A 15-mile stretch of the river near Natchez, Miss., has been closed, said Coast Guard Petty Officer Bill Colclough. The National Weather Service says the river has risen to a flood-stage level of 62.8 feet. “It’ll be closed until further notice,” Colclough said. The New Orleans Times-Picayune said on its website Tuesday that the river is expected to crest Saturday at 63 feet in Natchez, five feet above a record set there in 1937. It could take several weeks for water levels to return to normal. Natchez is well north of where deep-draft ships are allowed on the Mississippi; those vessels are allowed only as far as Baton Rouge. But bulk cargo traffic is expected to be severely affected by the move. Some cargo normally loaded off deep-draft, oceangoing ships and onto barges for transport further up river may be halted. Conversely, barge traffic headed for Baton Rouge and points south may not be able to get to destinations in time for off-loading to larger ships. The closure is expected to put a severe crimp in the operations at the Port of South Louisiana, just up river from New Orleans, the largest in the Western Hemisphere in tonnage handled. The port receives 55,000 barges each year as well as 4,000 oceangoing vessels, according to its Web site. While other ports such as New Orleans handle mostly container traffic that is loaded onto rail cars and trucks, the Port of South Louisiana deals primarily in break bulk and dry bulk — usually the cargo handled on barges that travel further up the Mississippi. Port of South Louisiana officials could not be reached for immediate comment. At the Port of New Orleans, officials say they have been told that spillways diverting water from the Mississippi should keep water levels at a flood-stage level of 17 feet. “New Orleans is already cresting,” said Chris Bonura, port spokesman. New Orleans shipping traffic affected by the barge shutdown at Natchez should be minimal, Bonura said. A total of 35% of its ships deal in break-bulk cargo such as steel or forest products. He said an unknown portion of that comes to the port through barges. If the shutdown is short-term, many shippers going in and out of that port could probably work around it, Bonura said. They could offload whatever cargo is needed for what is called “hotshot” deliveries and send it by rail or truck. “As long as it’s a short-term closure, that’s something you could work around with that kind of strategy,” Bonura said. Meanwhile the strategy to open nearly all the gates of the Bonnet Carre Spillway just upstream of New Orleans, along with portions of the Morganza Spillway north of Baton Rouge, seems to be working, reports say. Fifteen of the 125 gates at Morganza have been opened, sending water south into the Atchafalaya Basin toward the Gulf of Mexico, the Times-Picayune said. The number of opened floodgates has remained steady since Monday, but is expected to double at some point. Louisiana Gov. Bobby Jindal was quoted by the paper as saying the water shooting down the basin is moving more slowly than expected, speculating that some of it was being absorbed into the earth. Russ Britt is the Los Angeles bureau chief for MarketWatch.