A huge chemical tank was floating down the Chattahoochee River Friday afternoon, until authorities fished it out, according to Channel 2 Action News.

Douglas County officials were able to take a closer look at the drum, which measured about 12 feet long and 9 feet tall. They then tied it in place to secure the drum until it could be taken out Saturday morning.

“We have found just about everything you can possibly imagine during our cleanup and river patrols, but this one’s new,” river keeper Jason Ulseth told Channel 2.

The massive metal drum was empty, but the find prompted an investigation by the United States Environmental Protection Agency. Authorities want to know whether or not the tank ever held toxic contents.

Ulseth told the station he has never seen a drum this size. He said the drum has stickers with red and black letters warning the tank may contain lethal fumes, a picture of a skull and cross bones, and several ‘Warning: Danger ’ notices.

“The most concerning part was whether or not there were actual chemicals in this tank,” Ulseth said.

The organization alerted the EPA and an emergency response unit responded to the Chattahoochee at first light Saturday to inspect, then carefully tow the tank down river, according to Channel 2.

They could tell it was empty, but initial tests inside the drum found no evidence of hazardous compounds or a toxic release into the water.

“And they weren’t able to detect any of those volatile chemicals, which was good,” Ulseth said.

It took a while, but they got the tank to a boat ramp and up onto a trailer. The mystery remains as to what exactly was inside and where it came from.

“But EPA is looking into that,” Ulseth said.

The investigation can look for ID or serial numbers on the tank and possibly trace it back to who dumped it.

More chemical testing can find out what was stored in it.