Lawyers for the Justice Department and BP PLC – the oil company largely responsible for spilling millions of gallons of oil into the Gulf of Mexico in 2010 – finished arguing in court on Friday over exactly how much oil was discharged.
Government experts estimated that the Deepwater Horizon disaster, which killed 11 workers, caused 176 million gallons of oil to spill into the Gulf. BP attorneys have urged U.S. District Judge Barbier to set the figure at nearly 103 million gallons.
The final number will determine how much BP pays for the cleanup. Using government figures, a maximum penalty if the company is found grossly negligent could total $18 billion. The company's figures would result in a $10.5 billion fine.
As both sides argued in court, Louisiana's Coastal Protection and Restoration Authority revealed this week that significantly more oil had been found in the Gulf so far this year.
In the first eight months of 2013, some 3.01 million pounds of "oily material" were cleaned up on Louisiana's coast, up from 119,894 pounds in the same period last year, according to the state's Department of Natural Resources.
While the state did not reveal why there was a more than 20-fold increase in the amount collected this year, some believe Tropical Storm Karen, which occurred earlier in October, may have washed away sand and exposed more oil.
Some of the oil, especially so-called tar balls, apparently washed ashore after Karen hit.
The report said more than 200 miles of Louisiana shoreline still display some degree of oil pollution after the largest offshore crude spill in U.S. history.
The findings prompted some to say that the cleanup efforts since 2010 have been lackluster.
"The conventional wisdom would be that the number (of pounds of oily materials collected) should go down, obviously," Garret Graves, chairman of the Coastal Protection and Restoration Authority, told Reuters Thursday. "But if the response effort was insufficient ... I think the numbers speak for themselves."
Danny Wallace, a BP incident commander, said the rise in recoveries this year stemmed from where BP was focusing its efforts after Hurricane Isaac rearranged sands in August, 2012.
"In 2013 most cleanup activities have focused on the barrier islands where Hurricane Isaac uncovered heavily-weathered residual oil that had been buried when tropical storms deposited deep layers of sand along the shoreline in 2010 and 2011," Wallace said.
He said the state had initially shied away from allowing the company to dig deeply to recover oily material, but after Isaac scooping up the oil became easier and posed fewer environmental risks.
U.S. District Court Judge Carl Barbier is expected to decide early next year how much BP should be fined for the spill under the Clean Water Act.
Al Jazeera and wire services