The Negative Effects of Hydraulic Fracturing

The Academy Award-nominated documentary, "Gasland," raised a stir in 2010 with its depiction of the negative environmental effects of hydraulic fracturing, or "fracting" -- a controversial method of extracting natural gas from deep within the earth. While the gas industry maintains that the practice is harmless and necessary to wean America from foreign energy sources, residents living near fracting operations, including those appearing in "Gasland," have enlisted the help of the government to find the truth about fracting, or at least why the tap water in their homes has become flammable.

The Process

• The process of fracting involves the high-pressure injection of sand, water and proprietary chemicals into shale rock about a mile or more under the earth's surface. The pressurized mixture opens cracks in the rock through which the gas escapes and is then collected. The natural gas drilling industry claims that the process is the most efficient and economical way to collect the estimated 262 trillion cubic feet of gas believed to be lying underground in a vast shale formation stretching from New York to Virginia.

Methane

• According to a May 2011 story in "Engineering News," researchers from Duke University found unusually high levels of the combustible gas, methane, in drinking-water wells near fracting sites. Studying 68 private wells in northeastern Pennsylvania and New York, scientists discovered measurable methane levels in 85 percent of the wells. However, wells within a kilometer of fracting sites had levels an average of 17 times higher than well that are more distant. Although the industry-friendly think-tank Energy-in-Depth disputes the study's findings, residents who live near fracting sites believe the study answers questions about their ignitable tap water.

Trace Chemicals and Health Worries

• A September 2009 Associated Press story features residents of Casper, Wyoming who claim fracting in the nearby Pavillion gas field has contaminated their water wells with toxic chemicals and caused the area's unusual health problems, including liver disease, seizure disorders and a rare cancer. Though the Environmental Protection Agency found traces of chemicals such as arsenic and cobalt in 11 of the 39 wells it tested in the area, the operator of the fracting site, EnCana Corp., believes the contamination was not a result of the controversial gas extraction process and could have been created by a number of other sources.

South Africa

• In response to a letter of objection written by the environmental group, Treasure the Karoo Action Group, the South African government turned down Shell Oil's request to begin fracting in the natural gas-rich area of the country known as Karoo. Minister of the Department of Mineral Resources Susan Shabangu said the 2011 ban would be extended until an expert study on fracting and its effects on the environment was completed. In May 2011, the environmental group Earthlife Africa launched a nationwide boycott of Shell because of its plans to "fract" in South Africa.