Where All That BP Oil Is

There seems to be some concern about where all the oil from the BP oil spill/leak in the Gulf of Mexico has gone. ABC News's report is here. I have a thought: maybe there just isn't that much oil to find. I did some figuring this morning. The EPA tells us that the Gulf of Mexico contains 6.43 x 10¹⁷ or 643 quadrillion gallons of water. The spill is said to be 200 million gallons (200 x 10⁶ gallons). By my math, that comes to about three gallons of oil in every 10⁹ (billion) gallons of water. Let's say for the sake argument that the spill area is only a thousandth of the Gulf. That makes the concentration in the spill area about 3 parts per million (ppm). The current legal EPA limit for oil discharge into the ocean is 15ppm--five times this calculated concentration. It looks like there just wasn't much oil in the spill/leak to begin with, so maybe it isn't missing.