(Bloomberg News) Halliburton Co. and Baker Hughes Inc.'s BJ Services are among 12 oil and gas companies using diesel fuel in hydraulic fracturing, potentially violating the law, three U.S. House Democrats said.

The providers injected 32.2 million gallons of unauthorized diesel fuel, or fluids containing the fuel, to extract gas from wells in 19 states from 2005 to 2009, Representatives Henry Waxman, Edward Markey and Diana DeGette wrote today in a letter to Environmental Protection Agency Administrator Lisa Jackson. BJ Services led with 11.5 million gallons followed by Halliburton at 7.2 million, they said.

Companies using hydraulic fracturing--a technique that shoots water, sand and chemicals into shale to extract natural gas--aren't required to get permits unless they use fluids containing diesel, which the EPA said is a threat to drinking water. No companies sought such permits, the lawmakers said.

"This appears to be a violation of the Safe Drinking Water Act," according to the letter from Waxman of California, Markey of Massachusetts and DeGette of Colorado. "It also means that the companies injecting diesel fuel haven't performed the environmental reviews required by the law."

Schlumberger Ltd., the No. 1 provider of oil-field services, Halliburton, the second biggest, and BJ Services agreed with the EPA in 2003 to stop using diesel fuel in fracturing fluids for coalbed methane production. Such wells tend to be closer to sources of drinking water than other oil and gas production wells.

Companies Comply

Halliburton, BJ Services and Schlumberger said they comply with the agreement and aren't using diesel fuel in coalbed methane wells, according to the letter. Three smaller companies told the lawmakers that they have used a limited amount of diesel in such wells, without providing information on the proximity to drinking-water sources, the lawmakers said.

None of the oil and gas service companies provided information on whether they performed hydraulic fracturing in or near underground sources of drinking water, the lawmakers wrote to Jackson.

"A key question is whether the unauthorized injection of hydraulic fracturing fluids containing diesel fuel is adversely affecting drinking water supplies," according to the letter.

Houston-based Halliburton said in a statement today that it doesn't believe the fracturing activities have violated any U.S. laws and it "is firmly committed to meeting all of the regulatory requirements applicable to hydraulic fracturing."

'New Technologies'

The company has implemented "new technologies for hydraulic fracturing that provide an extra margin of safety for public health and the environment," according to the statement.

A spokesman for Baker Hughes, the oil-field contractor that acquired BJ Services last year, and a spokeswoman for Schlumberger didn't respond to requests for comment. Both companies are based in Houston.

The EPA is collecting information as part of a study into the effects of hydraulic fracturing on drinking water. Gas from shale may total half of the U.S. natural-gas supply by 2035, up from 20 percent today, according to IHS Cambridge Energy Research Associates, a Cambridge, Massachusetts-based adviser to energy companies.

The EPA said today that it's planning to clarify the permitting process for the use of diesel fuel in hydraulic fracturing.

"Our goal is to put in place a clear framework for permitting so that fracturing operations using diesel receive the review required by law," the agency said in an e-mailed statement.

Industry, Environmentalists

The Independent Oil & Gas Association of New York, an industry group whose directors include representatives from Halliburton, has said fracturing is safe. Environmental groups led by the New York-based Natural Resources Defense Council said the chemicals used are often toxic, citing cases in Wyoming and Pennsylvania where residents were told not to drink well water.

The House Oversight and Government Reform Committee began its investigation of fracturing in February 2010.

The panel concluded that 12 of 14 companies questioned used diesel fuel or fluids containing diesel in 19 states. Texas accounted for half of the total. Companies used at least 1 million gallons of diesel-containing fluids in Oklahoma, Wyoming, North Dakota, Louisiana and Colorado, the lawmakers said.