The spill was discovered near New Cumberland, Hancock County, early Monday.

Tom Szymanek, who owns a nearby campground, said he saw the spill, but authorities told him there was no problem.

"They said they called over there and there's nothing in the barge, but pretty soon there won't be anything in the barge -- it's all in the water," Szymanek said.

Officials with the Mine Marine Safety Unit said the responsible people are aware of the problem, and they are working to complete salvage work on the barge. They said the coal does not pose a threat to the water.

But families who planned to spend the day on the river decided to scrap those plans after taking a look at the water.

Kristi Cremeans, of Rootstown, Ohio, said, "The kids saw like a stream of what we thought was diesel fuel ... or oil. It was just running straight down with the current."

Tammy Dolin, also of Rootstown, said, "We were going to figure out where we could find a clean spot in the water to swim."

The coal is blanketing the water with a thick black scum.

"What's it doing to the fish? ... It's just coagulating on top of the water," Cremeans said.

Marine Safety officials said it may take some time to clean up the mess.

Stay with NEWS9 for continuing coverage.

-Renee Cardelli & Jackie Cain, NEWS9