LAFAYETTE — A federal judge has fined CITGO Petroleum $9 million in connection with a 2006 oil spill at the company’s Lake Charles refinery.

U.S. District Judge Richard Haik filed the ruling this week following a trial earlier this year in a Clean Water Act lawsuit brought by the U.S. Environmental Protection Agency.

Haik ordered CITGO to pay $6 million to federal regulators and $3 million to state regulators.

The judge also ordered CITGO to carry out several projects to help prevent future spills at the refinery.

CITGO has already paid $13 million in fines after pleading guilty in 2008 to a criminal charge in the spill.

In the civil case, CITGO admitted fault in the spill but contested the government’s figures for how much oil was spilled and argued against the more than $200 million in penalties that federal regulators sought.

The June 2006 oil spill occurred during heavy rains in the Lake Charles area that caused two “slop oil” tanks to overflow into a containment area and then into nearby waterways.

Slop oil is a mixture of oil, water and other waste substances from the refining process.

Federal regulators had argued that 76,800 barrels of waste oil flowed into area waterways, while experts with CITGO argued that the amount was 54,000 barrels.

Haik wrote in his ruling that there was not sufficient evidence to determine the exact amount but that he found CITGO’s figure to be more reasonable.