A report on how the Federal Safe Drinking Water was amended by the U.S. Congress in 2005 to exempt hydraulic fracturing from its regulations.

WASHINGTON — Over the last four years, the Bush administration and Vice President Dick Cheney's office have backed a series of measures favoring a drilling technique developed by Halliburton Co., Cheney's former employer.

The technology, known as hydraulic fracturing, boosts gas and oil production and generates $1.5 billion a year for the company, about one-fifth of its energy-related revenue. In recent years, Halliburton and other oil and gas firms have been fighting efforts to regulate the procedure under a statute that protects drinking water supplies.

The 2001 national energy policy report, written under the direction of the vice president's office, cited the value of hydraulic fracturing but didn't mention concerns raised by staff members at the Environmental Protection Agency.

Since then, the administration has taken steps to keep the practice from being regulated under the Safe Drinking Water Act, which Halliburton has said would hurt its business and add needless costs and bureaucratic delays.

An EPA study concluded in June that there was no evidence that hydraulic fracturing posed a threat to drinking water. However, some EPA employees complained about the study internally before its completion, and others have strongly criticized it publicly since its release.