BP now challenging federal estimate of spilled oil

In the early weeks of this summer's BP oil disaster, many experts said the oil giant had an obvious interest in lowballing estimates of how fast oil was gushing from its busted well in the Gulf of Mexico. After all, such critics said, the less oil that appeared to flow, the less BP's liability in court. So while the actual flow rate was enormous, the company insisted for some time that its well was spewing just 5,000 barrels a day.

Eventually, detailed analysis by federal and nongovernment scientists concluded that the BP well had lost roughly 60,000 barrels a day, meaning that some 4.9 million barrels had soiled the gulf during the spill. BP posed no notable public objections to that figure.

Now BP is back to lowballing the spill, insisting that these later numbers are "flawed" and "highly unreliable." Researchers with the oil giant say they believe the amount of oil spilled perhaps half of the 60,000 barrels estimated, though they've presented no data to back that assertion up.

The co-chair of the president's National Oil Spill Commission was incredulous when he learned of BP's challenge to the government figures on Friday.

"They're going to argue that it was 50 percent less than that, possibly? Wow," Bob Graham said to the commission's deputy chief counsel. Graham is a former Florida senator and governor.

Depending how the numbers dispute gets resolved, it could mean a great shift in the oil giant's balance sheet. BP now stands to be fined between $1,100 and $4,300 per barrel under the Clean Water Act -- a range that hinges on how much the courts believe the disaster arose from corporate negligence on BP's part. At the current estimate, that means that BP could be on the hook for $21 billion -- a sum that many government and legal players want to use for a huge Gulf Coast restoration project.

In a statement Friday, the Department of Energy insisted that its estimates were accurate.

"The government's estimates about the flow rate were based on the best available data and rigorous analysis by world-leading scientists from inside and outside of government and the full resources of our national laboratories," said Stephanie Mueller, an agency spokeswoman.

(Photo of Gulf Coast oil: AP/Gerald Herbert)