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New Flow Rate Estimates Match an Earlier, Unpublicized Number Used by BP

New flow rate estimates make the Gulf oil spill the largest unintentional spill in history. The new estimates also match a number BP cited to the Coast Guard in early July.

A team of scientists assembled by the government has released new estimates of the oil flow from BP's ruptured well in the Gulf of Mexico, pegging it at 62,000 barrels per day toward the start of the disaster and 53,000 barrels per day just before it was capped in mid-July.

The 53,000-barrels-per-day number is identical to the figure that BP was using in early July in correspondence with the Coast Guard. That number was not publicized, but was found in two letters noted by Rep. Edward Markey.

In those letters, BP wrote to the Coast Guard to request exemptions to apply dispersant on the surface of the Gulf, making the case for the volume of dispersant it wished to apply by “assuming a flow rate of 53,000 bbls/day.” (Read one such letter.)

Prior to this week’s revised estimates, the official flow rate estimate was a much wider range of 35,000 to 60,000 barrels per day. The fact that BP cited a flow rate on the higher end of the range—an assumption identical to this week’s official estimate—would seem to suggest that the company may have known the well was close to its worst-case scenario.

But when I asked BP about the matching numbers, spokesman Mark Proegler said the earlier flow rate assumption was a "government-mandated" assumption, used at the request of the EPA and the Coast Guard. Proegler said the number was the expected containment capacity of three vessels used to capture oil. (We've asked the EPA and the Coast Guard about this and are waiting for a response.)

"It does seem to be a bizarre coincidence, that now the Flow Rate Technical Group is saying that’s the rate," Proegler told me. 

In May, BP had told some lawmakers behind closed doors that the flow rate could be as much as 60,000 barrels per day. The latest flow rate estimate shows that at times, it was worse.

The Flow Rate Technical Group estimated that in all, BP’s well spewed about 4.9 million barrels—more than 200 million gallons of crude—before it was temporarily capped. Only about 800,000 barrels—about 16 percent—was captured, leaving a significant amount of oil still in the Gulf.

Flow rate, as we’ve pointed out, matters for a number of reasons—not least of which, at this point, are the fines the company will have to face.

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