DENVER (AP) - Colorado regulators grappling with a historic energy boom that's pushing oil rigs to the very doorsteps of suburban schools and homes were among the first in the nation to require companies to disclose the chemicals they use in their new drilling techniques.
Now, the regulators have issued what they tout as the country's toughest energy drilling regulations, requiring rigs to be at least 500 feet away from occupied buildings and take other steps to limit pollution.
But few are pleased, underscoring the difficulties that governments across the country are facing as they try to regulate an industry that is moving ever closer to people's neighborhoods but also contributing jobs and millions of dollars to local economies.
"Colorado has been on the leading edge of" regulating the energy boom, said Bruce Baizel, who tracks regulations nationwide for the environmental group Earthworks. "It's trying to muddle through and not satisfying anybody."
Environmentalists complain the new regulations have too many loopholes, while the energy industry frets they will create more hoops to jump through before it can hire people to extract the oil or gas from the ground.
"There is so much energy in the ground that we can access, that it's coming into more people's backyards than ever before," said Julia Bell, a spokeswoman for the Independent Petroleum Association of America. "The tension is popping up everywhere."
Colorado is one of many that has dealt with the explosion in energy extraction that analysts say may enable the United States to overtake Saudi Arabia as the world's top energy producer in a decade.
The same boom has brought drilling rigs, and the fears of air and water pollution that accompany them, into densely-populated urban areas.
Innovations like hydraulic fracturing, known as "fracking," have made it easier to extract oil and especially natural gas from energy-rich geological formations such as the Niobrara shale, which stretches from Wyoming to beneath the densely-populated Front Range of Colorado's Rocky Mountains.
Last year, more than 150 bills were introduced in 25 states to regulate energy drilling, said Jacquelyn Pless, an analyst at the National Conference of State Legislatures. Only 14 became law, many to define whether state or local governments could regulate the procedure.
In the Denver suburb of Longmont, residents passed a ballot initiative in November banning hydraulic fracking.
An industry group has filed a lawsuit to overturn the ban, arguing only the state can regulate energy exploration. There is a similar challenge over Longmont's own drilling regulations, which are more stringent than even the state's new ones.
Other cities have already embarked on similar paths.
The university town of Fort Collins, Colo., gave preliminary approval to its own fracking ban. In Pittsburgh, the cradle of the American energy industry in the 19th century, banned new drilling projects within city limits in 2010, but the state is challenging the authority of cities to issue such bans.