"More than 27,000 abandoned oil and gas wells lurk in the hard rock beneath the Gulf of Mexico, an environmental minefield that has been ignored for decades. No one — not industry, not government — is checking to see if they are leaking, an Associated Press investigation shows.

The oldest of these wells were abandoned in the late 1940s, raising the prospect that many deteriorating sealing jobs are already failing.

The AP investigation uncovered particular concern with 3,500 of the neglected wells — those characterized in federal government records as "temporarily abandoned."

Regulations for temporarily abandoned wells require oil companies to present plans to reuse or permanently plug such wells within a year, but the AP found that the rule is routinely circumvented, and that more than 1,000 wells have lingered in that unfinished condition for more than a decade."

Jeff Donn and Mitch Weiss report for the Associated Press July 7, 2010. [2]