More than 3,200 oil and gas wells classified as active lie abandoned beneath the Gulf of Mexico, with no cement plugging to help prevent leaks that could threaten the same waters fouled by last year's BP spill, The Associated Press has learned. These wells likely pose an even greater environmental threat than the 27,000 wells in the Gulf that have been plugged and classified officially as "permanently abandoned" or "temporarily abandoned." Those sealed wells were first tallied and reported as a major leaking threat in an investigative report by the AP in July. The unplugged wells haven't been used for at least five years, and there are no plans to restore production on them, according to the federal government. Operators have not been required to plug the wells because their leases have not expired.

As a result, there is little to prevent powerful leaks from pushing to the surface. Even depleted wells can repressurize from work on nearby wells or shifts in oil or gas layers beneath the surface, petroleum engineers say. But no one is watching to make sure that doesn't happen.