BP PLC could face up to $13.7 billion in civil penalties under the U.S. Clean Water Act for its role in the Deepwater Horizon oil spill, according to a federal judge’s ruling on Thursday.

U.S. District Judge Carl Barbier of the Eastern District of Louisiana sided with the U.S. Department of Justice that BP’s maximum allowable fine under the Clean Water Act should be $4,300 per barrel—an amount for gross negligence adjusted by the Environmental Protection Agency for inflation.