"CHEYENNE, Wyo. — A state agency that oversees oil and gas development voted Tuesday to require energy companies to disclose what chemicals they're pumping underground to improve the flow of oil and gas into well bores.

The state Oil and Gas Conservation Commission unanimously approved the new rules, which cover a variety of drilling practices including hydraulic fracturing. Commonly called "fracking," the process involves pumping pressurized water, sand and chemicals underground to crack open fissures in rock.

Environmentalists said they approve of the new rules, and industry officials said they can live with the changes."

Mead Gruver reports for the Associated Press June 8, 2010. [2]