The Coast Guard said there are roughly 550 skimmers working in the Gulf, with 250 or so in Louisiana waters, 136 in Florida, 87 in Alabama and 76 in Mississippi, although stormy weather in recent days has kept the many of the vessels from working.

The frustration extends to the volunteers who have offered to clean beaches and wetlands. More than 20,000 volunteers have signed up to help in Florida, Alabama and Mississippi, yet fewer than one in six has received an assignment or the training required to take part in some chores, according to BP.

The executive director of the Alabama Coastal Foundation, Bethany Kraft, said many people who volunteered are frustrated and angry that no one has called on them for help.

"You see this unfolding before your eyes and you have this sense that you can't do anything," she said. "To watch this happen in our backyard and not be able to help is hard."

Some government estimates put the amount of oil spilled at 160 million gallons. That calculation was arrived at by using the rate of 2.5 million gallons a day all the way back to the oil rig explosion. The AP, relying on scientists who advised the government on flow rate, bases its estimates on a lower rate of 2.1 million gallons a day up until June 3, when a cut to the well pipe increased flow.

By either estimate, the disaster would eclipse the Ixtoc disaster in the Gulf two decades ago and rank as the biggest offshore oil spill during peacetime. The biggest spill in history happened in 1991 during the Persian Gulf War, when Iraqi forces opened valves at a terminal and dumped about 336 million gallons of oil.

The total in the Gulf disaster is significant because BP is likely to be fined per gallon spilled. Also, scientists say an accurate figure is needed to calculate how much oil may be hidden below the surface, doing damage to the deep-sea environment.

"It's a mind-boggling number any way you cut it," said Ed Overton, a Louisiana State University environmental studies professor. "It'll be well beyond Ixtoc by the time it's finished."