Cleanup crews worked Saturday to empty a ruptured barge that leaked about 10,000 gallons of petroleum waste water into the Grand River, killing catfish but causing little other apparent environmental damage.

The barge, leased to GSX Corp. and carrying Exxon Chemical Co. products, ruptured while unloading Friday at a dock on the river, a slow moving stream much like a bayou that empties into the Intracoastal Waterway about 70 miles west of New Orleans.The waterway, just below where the river enters, has inlets into marshland and swamps that 70 miles to the south meet the Gulf of Mexico.

Jill Johnson, spokeswoman for Exxon Chemical in Houston, said crews must first empty the barge of an estimated 500,000 gallons of the liquid - a process called lightering - before beginning skimming and other cleanup operations on and in the water.

"We will continue lightering through the better part of today and perhaps tomorrow," she said Saturday. "The process is slow."

The liquid was first pumped into tanker trucks, but each truck carries only about 30,000 gallons and takes two to three hours to load. Another barge was moved up next to the ruptured barge Friday night, and the remaining liquid was being pumped into it.