A fuel tanker overturned in Monroe County Wednesday afternoon. It happened about a mile and a half south of Highway 18 on Highway 87.

According to Monroe County Fire Department Battalion Chief Jason Lott, the tanker was carrying close to 1,000 gallons of diesel fuel, and most of it leaked out after the truck rolled onto its side.

The tanker has been cleared from the scene, but Lott says most of that diesel fuel ran downhill and into Rum Creek just beyond an embankment.

The Federal Environmental Protection Agency arrived on the scene assess what Lott expects to be a "costly cleanup."

Lott says the fuel tanker was the only vehicle involved in the crash. The driver was not injured.

Sergeant Lawson Bittick of the Monroe County Sheriff's Office says the cause isn't yet known, but witnesses say the truck veered from the northbound lane across the southbound lane into a ditch. Bittick says the driver may have fallen asleep.

Mary Gibson says she could smell fuel in the creek hours after the accident.

"I live on Rum Creek and the Ocmulgee River where the creek flows into the river, and I'm trying to let somebody know that this spill has reached the river," she said.

She said she saw "an oily substance on top of the water."

Another creek neighbor, Wayne Barlow, says he's lived near Rum Creek for decades, and up until last year, relied on well water. He says if he still had it today, he'd be worried.

"I'd get it tested," he said. "I really would, and (I would) keep testing it for a few months."

The EPA could not be reached for comment Wednesday.