The flow of oil into the Gulf of Mexico seems to have stopped for now, according to the federal government's top oil-spill commander, U.S. Coast Guard Adm. Thad Allen.
On Wednesday, BP and government engineers began an effort called "top kill," which pumps heavy drilling mud into the pipe. So far, they've pumped enough drilling fluid to block oil and gas from spewing from the well, Allen said. The pressure from the well was very low, he said, but persisting.
Once engineers reduce the well pressure to zero, engineers will pump cement into the hole to permanently seal the well. Although stopping short of declaring success, Allen said he's confident this will work. "We'll get this under control," he said.
Allen said progress is going well -- one ship that was pumping fluid into the well had run out of the mud, and that a second ship was on the way.
New government estimates put the size of the leak at 12,000 to 19,000 barrels of oil per day. So after 37 days of leaking, that's about 19 million gallons on the low and, and up to 39 million gallons on the high end, making it by far the worst oil disaster in U.S. history. The Exxon Valdez spilled 11 million gallons into Prince William Sound in Alaska in 1989.
"This will be felt for generations to come," said Regan Nelson, senior oceans advocate at the Natural Resources Defense Council in Washington. "It's an unprecedented disaster."