Oil company Phillips 66 has been federally indicted in connection with alleged violations of the Clean Water Act in California, authorities said Thursday.

The Houston-based company is accused of discharging hundreds of thousands of gallons of industrial wastewater containing excessive amounts of oil and grease, the U.S. Department of Justice said.

The company allegedly dumped the wastewater from its Carson oil refinery into the Los Angeles County sewer system in 2020 and 2021 and did not report the violations, prosecutors said.

Phillips is charged with two counts of negligently violating the Clean Water Act and four counts of knowingly violating the Clean Water Act. The company faces up to five years of probation on each count and a maximum of $2.4 million in fines.

An arraignment date has not been set.

“Phillips 66 will continue its cooperation with the U.S. Attorney’s office and is prepared to present its case in these matters in court,” a spokesperson said in a statement Thursday. “The company remains committed to operating safely and protecting the health and safety of our employees and the communities where we operate.”

Last month, Phillips announced it would close its Southern California refinery by the end of 2025, citing market concerns. That refinery accounts for about 8% of California’s refining capacity, according to the state’s Energy Commission.

The company also operates a refinery near San Francisco that accounts for about 5% of California’s refining capacity, according to the state Energy Commission.