Hardrock Excavating LLC owner Ben Lupo, of nearby Poland, appeared in court Thursday and pleaded not guilty, U.S. Attorney Steven Dettelbach said.
Lupo, 62, faces up to three years in prison, a $250,000 fine and a year of supervised release if convicted.
No attorney was listed for him in court records and there was no immediate comment in response to a message left at his office.
Authorities allege Lupo repeatedly directed that unknown amounts of drilling mud and brine be discharged into a sewer that empties into the Mahoning River watershed. They say Lupo admitted giving such orders six times, but an employee told authorities waste was dumped into the drain at least 20 times.
The employee told the investigators that Lupo had issued a directive to say, if questioned by officials about it, that the dumping had occurred only four or six times.
Investigators following up on an anonymous tip about the illegal dumping visited Hardrock, a brine hauler, two weeks ago and found a hose running from a storage tank into a storm drain, Dettelbach said. The facility's approximately 58 storage tanks each can hold about 20,000 gallons.
An Ohio Environmental Protection Agency crew went to the scene the following morning and found a tank drained to within 18 inches of the bottom. The amount allegedly drained wasn't specified.
The Ohio Department of Natural Resources revoked the permits of Hardrock and D&L Energy after workers at the companies' Youngstown headquarters reported seeing the material being dumped.
Dettelbach said the investigation is ongoing and declined to comment on whether others might be charged.
"Obviously the existence of Utica Shale and natural gas under our feet provide a great opportunity for Ohio, but it also provides a challenge for us," he said. "Companies and workers must follow the rules when they extract this valuable natural resource."
Ohio Attorney General Mike DeWine said the state intends to take civil action in the case in regard to allegations of illegal storage, transportation and disposal. DeWine says fines for such violations could total thousands of dollars daily.