A new report on hydraulic gas drilling says that the practice is injecting toxic petroleum distillates into thousands of wells, threatening drinking water supplies from New York to Wyoming. What's more, the Environmental Working Group says that hydraulic gas drillers regularly skirt the law, and that federal regulators look the other way.

The Environmental Working Group report is entitled "Drilling Around the Law." According to the report, distillates from hydraulic drilling include kerosene, mineral spirits and a number of other petroleum products that often contain high levels of benzene, a known human carcinogen that is toxic in water at even minuscule levels. Drillers inject these substances into the earth under extremely high pressure in a process called hydraulic fracturing that energy companies use to extract natural gas and oil from underground formations. The process, known as "fracking," fractures the rock to allow additional gas and oil to flow to the surface.

Fracking is currently used in 90 percent of the nation's natural gas and oil wells. The practice makes drilling possible in areas that 10 to 20 years ago would not have been profitable. Recently, the state of New York has been considering new regulations to allow fracking in its Marcellus Shale region. However, that region encompasses New York City's watershed in the Catskills, which supplies the city's drinking water. Officials in New York city have been quite vocal in their opposition to any drilling in the watershed. The U.S. Environmental Protection Agency (EPA) has also voiced concerns about the state's draft regulations, citing the affect drilling would have on public health and the environment. The EPA is urging the state to study the potential impact of the proposed drilling more extensively.

According to the Environmental Working Group, there is reason for New York City residents to be concerned about fracking in the state. The group found that petroleum distillates used in a single gas well could contain enough benzene to contaminate more than 100 billion gallons of drinking water to unsafe levels, according to drilling company disclosures in New York state and published studies. That is more than 10 times as much water as the entire state of New York uses in a single day.

The group found that fracking has already been linked to drinking water contamination and property damage in Colorado, Ohio, Pennsylvania and Wyoming. Even so, Congress in 2005 exempted hydraulic fracturing, except fracturing with diesel fuel, from regulation under the Safe Drinking Water Act. The exemption followed lobbying by Halliburton and other energy companies, the Environmental Working Group said.

Diesel - itself a petroleum distillate - is the only substance for which drillers must seek a permit before it is injected underground and some companies have pledged not to use it in certain circumstances. Yet according to the Environmental Working Group, other petroleum distillates used openly by the industry contain the same toxic chemicals found in diesel at levels that can be much higher.

What's more, the group found that state and federal regulators are generally not tracking fluids used in fracturing and some agencies, including the Wyoming Oil and Gas Conservation Commission (WOGCC), say the federal Safe Drinking Water Act completely exempts fracking - even with diesel. As a result, companies could easily be fracturing with diesel without a permit.

A Wyoming official who asked not to be identified by name told the Environmental Working Group that drilling companies in the state commonly use diesel for fracturing. The WOGCC was the only one of the five state or federal agencies contacted by the group that reported tracking the chemicals used in fracking operations. The other agencies contacted were in Pennsylvania, New York, Montana, and Texas.