Quite a lot bigger than the estimate being uncritically quoted throughout the media of 210,000 gallons (5,000 barrels) per day. That was the last “official” estimate made by NOAA and accepted by the Coast Guard back on April 29 (see timeline below). Before that, the Coast Guard estimates ranged from 336,000 gallons (8,000 barrels) per day, to zero, to 42,000 gallons (1,000 barrels) per day. None of these estimates has been publicly explained or substantiated. And on May 1, the Coast Guard and NOAA stopped trying to estimate the spill rate, with Admiral Thad Allen saying, “Any exact estimate is probably impossible at this time.”
But the media continues to report that oil is leaking into the Gulf at 5,000 barrels per day. At SkyTruth we estimate the spill rate is closer to 1.1 million gallons (26,500 barrels) per day, based on the size of the slick on satellite images and Coast Guard maps, and thickness estimates derived from visual descriptions of the slick. That puts us at a total spill of 21 million gallons so far.
Considering that there are deepwater oil wells in the Gulf of Mexico capable of producing >1.26 million gallons (30,000 barrels) of oil per day under controlled flow rates; and that the oil slick continues to grow in size even though it’s been under attack 24/7 by skimmer vessels, burning, chemical dispersants, and natural processes; our estimate seems quite conservative.
Why is it important to get this number right?</strong This is about more than just liability, or PR. You can bet that our future response capacity is going to be overhauled and retooled based on this spill. If we low-ball the spill amount and rate, we run the risk of designing an inadequate new spill-response system that is doomed to fail the next time something this big occurs.
Here’s the timeline of spill estimates:
- 4/22 – Deepwater Horizon rig sinks; Coast Guard estimates “up to” 8,000 barrels per day (bpd) is leaking – source
- 4/23 – Coast Guard reports no leaking at all from the damaged well – source
- 4/24 – Coast Guard reports well is leaking, estimates 1,000 bpd – source
- 4/25 – BP repeats 1,000 bpd estimate – source
- 4/27 – 1,000 bpd still the official Coast Guard and BP estimate – source
- 4/27 – SkyTruth and Dr. Ian MacDonald publish first estimate that spill rate is 20,000 bpd – source
- 4/28 – NOAA weighs in and raises the official estimate to 5,000 bpd based on aerial surveys “and other factors”; BP disputes this higher estimate – source
- 4/29 – Coast Guard and NOAA repeat their estimate of 5,000 bpd – source
- 4/29 – BP’s Chief Operating Officer admits new estimate of 5,000 bpd may be correct; “He said there was no way to measure the flow at the seabed and estimates have to come from how much oil makes it to the surface” – source
- 5/1 – SkyTruth and Dr. Ian MacDonald publish revised estimate of at least 26,500 bpd – source
- 5/1 – Coast Guard Admiral Thad Allen “acknowledged there was no way really to know the extent of the leak” – source – and stated that “Any exact estimate is probably impossible at this time” – source
- 5/1 – Coast Guard and NOAA cease estimating the rate of the spill. BP continues to use 5,000 barrels per day as their estimate of the spill rate.