Immediately after the explosion, BP and the
United States Coast Guard did not estimate any oil leaking from the sunken rig or from the well.
[39] On April 24, Coast Guard
Rear Admiral Mary Landry announced that a damaged wellhead was indeed leaking.
[40][41] She stated that "the leak was a new discovery but could have begun when the offshore platform sank ... two days after the initial explosion."
[40] Initial estimates by Coast Guard and BP officials, based on remotely operated vehicles as well as the oil slick size, indicated
the leak was as much as 1,000 barrels per day (160 m³/d).
[40] Outside scientists quickly produced higher estimates, which presaged later increases in official numbers.
[42][43][44] Official estimates increased from 1,000 to 5,000 barrels per day (160 to 790 m³/d) on April 29,
[45][46] to 12,000 to 19,000 barrels per day (1,900 to 3,000 m³/d) on May 27,
[47][48][49][50] to 25,000 to 30,000 barrels per day (4,000 to 4,800 m³/d) on June 10,
[51][52][53] and to between 35,000 and 60,000 barrels per day (5,600 and 9,500 m3/d), on June 15.
[54][55] Internal BP documents, released by Congress, estimated the flow could be as much as 100,000 barrels per day (16,000 m3/d), if the
blowout preventer and wellhead were removed and if restrictions were incorrectly modeled.