Among the many dubious provisions in the 2005 energy bill was one dubbed the Halliburton loophole, which was inserted at the behest of - you guessed it - then-Vice President Dick Cheney, a former chief executive of Halliburton. It stripped the Environmental Protection Agency of its authority to regulate a drilling process called hydraulic fracturing [commonly referred to as fracking"]. Invented by Halliburton in the 1940s, it involves injecting a mixture of water, sand and chemicals, some of them toxic, into underground rock formations to blast them open and release natural gas. Hydraulic fracturing has been implicated in a growing number of water pollution cases across the country. It has become especially controversial in New York, where regulators are eager to clear the way for drilling in the New York City watershed, potentially imperiling the city's water supply. Congress last week approved a bill that asks the E.P.A. to conduct a new study on the risks of hydraulic fracturing. An agency study in 2004 whitewashed the industry and was dismissed by experts as superficial and politically motivated. This time Congress is demanding "a transparent, peer-reviewed process." Cumbersomely named the Fracturing Responsibility and Awareness of Chemicals Act, it would close the loophole and restore the E.P.A.'s rightful authority to regulate hydraulic fracturing. It would also require the oil and gas industry to disclose the chemicals they use.