By Jemima Kelly
NEW ORLEANS (Reuters) - The amount of oil found on Louisiana's coast has surged this year, three years after BP's Macondo spill in the U.S. Gulf of Mexico, the state's Coastal Protection & Restoration Authority said.
Some 3.01 million pounds of "oily material" were cleaned up on Louisiana's coast from March to August this year, up from 119,894 pounds in the same period last year, according to a report on the state Department of Natural Resources website.
BP said its own tally showed 3.1 million pounds of oily debris collected in the first nine months of this year, up from 941,000 pounds a year ago. A spokesman for the authority declined immediate comment.
The state presentation did not say why there was a big increase in the amount collected this year, but a U.S. Coast Guard official said frequent tropical storms can move sands around on beaches to either cover up oily material or expose it.
The state's presentation 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 conventional wisdom would be that the number (of pounds of oily materials collected) should go down, obviously. But if the response effort was insufficient ... I think the numbers speak for themselves," Garret Graves, the chairman of the authority told Reuters late on Thursday.
Danny Wallace, 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.
BP added that some of the oil on the shore could have come from natural seeps on the seafloor.
It also said that much of the material collected - up 90 percent - was sand, shells and water. The U.S. Coast Guard said about 20 percent of the material collected was oil.
The coastal authority represents several public agencies and helps coordinate BP's restoration work.
This month in New Orleans, lawyers for BP and the federal government tussled in court over how much oil spilled during the 87 days it took before workers were able to cap the well mishap that killed 11 men.
U.S. District Court Judge Carl Barbier is expected to decide early next year how much BP should be fined under the Clean Water Act for the spill.
The government has told the court that some 4.9 million barrels spilled. BP has estimated just 3.26 million barrels escaped into the sea. Both sides have acknowledged that 810,000 barrels of oil collected in cleanup will be excluded from the final amount.
(Writing by Terry Wade; Editing by Erwin Seba and David Gregorio)