BP's Gulf Oil Spill Worst in U.S. History

New estimates of the flow of oil released from the broken well in the Gulf of Mexico confirm that twice as much oil as was previously reported has been spewing into ocean, making the spill the nation's worst environmental disaster in history. Meanwhile, BP's (BP) "top kill" effort to seal the broken well is continuing Thursday, but the Coast Guard would not confirm news reports of its success.

U.S. Geological Survey Director Dr. Marcia McNutt revealed on Thursday that a new analysis calculates that the flow of oil coming from the broken well was at least twice the 5,000 barrels per day estimate that has previously been reported. McNutt said that observations of oil on the surface of the Gulf and video analysis of oil escaping from the broken pipe indicate that anywhere from 12,000 to 19,000 barrels of oil per day was escaping from the broken well prior to the "top kill" procedure. The new estimates seem to confirm that BP's oil spill has far surpassed the 250,000 barrels of oil spilled from the Exxon Valdez in 1989, making it the worst oil spill in U.S. history.

When asked why the previous estimate was so wrong, McNutt explained that earlier efforts to estimate the flow of oil were based on limited data, which resulted in wide-ranging readings from 1,000 to 13,000 barrels per day. She said officials "decided to take a number somewhere in the middle that was conservative, but defensible, and of course, reserved the right to revise it."

Reports early Thursday that Coast Guard Admiral Thad Allen had confirmed that engineers had pumped enough heavy drilling fluid, referred to as "mud," into the broken blowout preventer to block all oil and gas from escaping from the well, were later said to be incorrect. The Coast Guard hopes to have updates on its progress sealing the well later on Thursday. If the procedure is successful at stopping th flow of oil and reduces the pressure in the well to zero, engineers hope to cement it closed until relief wells can be drilled in coming months to siphon off the oil properly.

The news that the oil spill is the worst in the nation's history comes on the same day President Barack Obama is expected to announce a six month extension to the current moratorium on offshore drilling. Stricter federal guidelines and safety measures on such drilling are also expected to be implemented.