Nearly all of Alabama's 8,000 gas and oil wells are located on private land, and it is up to a small team of state regulators to inspect them.
Seven agents at the Alabama Oil and Gas Board are responsible for inspecting them, but state law doesn't spell out how often that must happen.
Butch Gregory, a petroleum engineer for the Oil and Gas Board based in Tuscaloosa, said one state agent in northern Alabama focuses on conventional wells, especially oil or natural gas. That agent visits about 650 wells at least once a year.
Two agents focus on the more common coal bed methane wells throughout northern Alabama originally designed to vent the gas from underground mines.
"There are thousands more of them and only a few agents," Gregory said. He estimated about 6,350 coal bed methane wells are permitted in Alabama.
Acting Deputy Director of the Oil and Gas Board Kirk McQuillan said agents know the history of well operators and focus on those with weak safety records. Operators must allow agents at well locations, must send in regular updates on well production and must report any spills to state and federal agencies.
"Oil and gas operations are an industrial activity, so by its very nature you have to be careful because accidents can happen," said Marvin Rogers, the board's general counsel.
Alabama has few oil and gas wells on federal land. But at least one well classified as having a high pollution risk has been inspected, according to federal data supplied to The Associated Press. Alabama is just one of six states where all oil or gas wells identified as high risk were inspected by federal regulators.
An Associated Press review of data provided by the U.S. Bureau of Land Management found four in 10 new oil and gas wells across the country identified as high risk were not inspected between 2009 and 2012.
The high risk category includes wells that could contaminate water or cause other safety and environmental issues. Bureau of Land Management officials said a boom in drilling made keeping up difficult.