By Karl Plume
(Reuters) - A stretch of the Ohio River near Paducah, Kentucky, was closed to shipping traffic after a barge tow ran aground in the receding waters, halting shipments of commodities such as grain and coal for at least the fourth time since September.
The U.S. Army Corps of Engineers said it had closed the nearly 90-year-old Lock and Dam 52 on Wednesday, and a backup of 32 towboats hauling 312 barges had assembled by midday on Thursday.
The area was the site of the worst river traffic jam in decades this autumn after closures caused by a malfunctioning dam triggered a backup of boats that at one time stretched more than 50 miles.
The latest river closure is expected to last into the weekend as crews remove the grounded vessel and raise the dam's wooden wickets to allow the pool of water upriver to rise, Army Corps spokeswoman Carol Labashosky said.
Once the dam is raised and the water pool is sufficiently high, vessels will be allowed to use the lock chamber to pass through the area, she said.
(Reporting by Karl Plume in Chicago; Editing by Andrew Hay and Lisa Von Ahn)