Updated

NEW ORLEANS (AP) — A federal report confirms what independent scientists have been saying for weeks about the Gulf oil spill: Undersea oil plumes extend for miles from the ruptured well.

The report may help measure the effectiveness of spreading chemicals to break up the oil.

Government researchers released a summary Wednesday of water sampling conducted last month near the site of the leaking well.

It describes a cloud of oil starting around 3,300 feet deep up to 4,600 feet deep and stretching up to 6 miles from the well. Levels of oil and gas within the cloud are significantly higher than concentrations closer to the surface.

The Environmental Protection Agency says there's been no significant harm to sea life, but marine scientist Vernon Asper of the University of Southern Mississippi says the levels are enough to kill fish.