NEW ORLEANS — The BP spill is by far the world’s largest accidental release of oil into marine waters, according to the most precise estimates yet of the well’s flow rate, announced by federal scientists on Monday.
Nearly five million barrels of oil have gushed from BP’s well since the Deepwater Horizon rig exploded on April 20, according to the latest data. That amount outstrips the estimated 3.3 million barrels spilled into the Bay of Campeche by the Mexican rig Ixtoc I in 1979, previously believed to be the world’s largest accidental release.
The BP spill was already thought to be the largest spill in American waters, but it was unclear whether it had eclipsed Ixtoc.
“We’ve never had a spill of this magnitude in the deep ocean,” said Ian R. MacDonald, a professor of oceanography at Florida State University.
“These things reverberate through the ecosystem,” he said. “It is an ecological echo chamber, and I think we’ll be hearing the echoes of this, ecologically, for the rest of my life.”
Federal science and engineering teams, citing data that are “the most accurate to date,” estimated that 53,000 barrels of oil a day were pouring from the well just before BP was able to cap it on July 15. They also estimated that the daily flow rate had diminished over time, starting at about 62,000 barrels a day and decreasing as the reservoir of hydrocarbons feeding the gusher was gradually depleted. Before Monday’s announcement, federal scientific teams had estimated the spill in a range from 35,000 to 60,000 barrels a day.
The teams believe that the current estimates are accurate to within 10 percent. They also reported that of the roughly 4.9 million barrels that had been released from the well, about 800,000 had been captured by BP’s containment efforts. That leaves over four million barrels that gushed into the Gulf of Mexico from April 20 to July 15.
As the estimates of the number of barrels spilled increases, so, too, do the penalties under the Clean Water Act, which calls for fines of $1,100 per barrel, or $4,300 per barrel if the government finds that gross negligence led to the spill.
At 4.9 million barrels, that means that the total fine could be $5.4 billion — and, if gross negligence led to the spill, $21 billion. If BP successfully argues that the 800,000 barrels it has recovered should mitigate the penalty, then the figure drops to $4.5 billion and $17.6 billion, respectively.
The amount of oil estimated to be pouring from the well has been a matter of dispute from the earliest days of the spill. Federal and BP officials initially announced that no oil appeared to be leaking, then 1,000 barrels a day, then 5,000 a day, frequently repeating that spill estimates are rough at best and that the main goal was to stop the well. But criticism mounted that no effort was being made to measure the leak with more certainty.