Obama aide urges listing of gas-drilling chemicals

A worker at EnCana's Frenchie Draw gas-drilling rig in central Wyoming guides sections of steel pipe into an 11,000-foot well in this September 19, 2009 file photo.

WASHINGTON (Reuters) - President Barack Obama's top environmental adviser urged the natural gas industry on Tuesday to disclose the chemicals it uses in drilling, warning that the development of massive U.S. shale gas reserves could be held back otherwise.

Joseph Aldy, special assistant to the president for energy and the environment, said concerns about water contamination from drilling chemicals could lead to states requiring disclosure and that could deter additional investment.

"You can't leave this in the status quo if you think we are going to have significant shale gas development in the United States," Aldy told Reuters after a natural gas conference.

Some energy companies decline to publish lists of toxic chemicals used in hydraulic fracturing, a technique used to extract natural gas from shale beds far underground.

Companies have been under pressure from critics of fracturing and from some lawmakers, who say the technique is damaging the water supplies of people who live near gas rigs.

Aldy said it is unclear whether fracturing chemicals are fouling groundwater but acknowledged the industry is under pressure from those who say the process leads to contamination with chemicals that can cause a range of illnesses.

"I don't think we have the information to assess that," he said.

Aldy said the industry could disclose the chemicals voluntarily, as some companies already do, or through regulation.

He declined to say whether the Obama administration supports the "Frack Act," a Congressional bill that would require drilling companies to disclose the chemicals and give the Environmental Protection Agency oversight over the industry, which is now regulated by the states.

EPA Administrator Lisa Jackson said on Monday she was "very concerned" about the composition of fracturing fluids and that she hoped the agency would conduct a study this year if it obtained funding.

U.S. shale gas reserves are estimated to contain enough of the clean-burning fuel to meet national demand for at least a century. A current boom in development has been made possible by fracturing technology that injects water, sand and a mix of chemicals to fracture the shale at high pressure.

(Editing by John O'Callaghan)