Two tugboats collided on the Mississippi River in Louisiana Saturday, dumping more than 69,000 gallons of crude oil into the river and stopping ship traffic, authorities said.

The oil spill posed a threat to drinking water supplies for thousands of people downriver from the accident site, about 80 miles above New Orleans, a Coast Guard spokeswoman said.Oil containment booms were placed around all water intake sites on the Mississippi downriver from the spill to avoid contamination, Lt. Cmdr. Laticia Argenti said.

The Coast Guard closed 13.5 miles of the river to all marine traffic to aid cleanup efforts, she said. The cleanup was expected to take several days "but we'll reopen the river as soon as possible, probably later today," she said.