"On Monday, BP said a cap was capturing 11,000 barrels of oil a day from the well. The official government estimate of the flow rate is 12,000 to 19,000 barrels a day, which means the new device should be capturing the bulk of the oil.

But is it? With no consensus among experts on how much oil is pouring from the wellhead, it is difficult -- if not impossible -- to assess the containment cap’s effectiveness. BP has stopped trying to calculate a flow rate on its own, referring all questions on that subject to the government. The company’s liability will ultimately be determined in part by how many barrels of oil are spilled."

Justin Gillis  and Henry Fountain report for the New York Times June 7, 2010. [2]