Documentation of Hydraulic Fracturing (fracking) drilling for natural gas in the Marcellus Shale formations in Dimock and Bradford County, Pennsylvania.
Some residents of these areas have filed lawsuits against gas companies alleging that the water wells they rely upon for domestic and agricultural use have been contaminated by nearby drilling processes.
Shale gas production has increased to a quarter of the U.S. natural gas supply in only five years, driven by new technology in hydraulic fracturing and high prices. The new processes involve drilling deep into shale rock formations as much as 7,000 feet (2,100 meters) and then horizontally into shale layers. Water, sand and chemicals under high pressure are injected into the rock to break them up (fracturing) and release gas or oil trapped in between the layers.
The Energy Policy Act of 2005 excluded hydraulic fracturing, except when diesel fuels are used, for oil and gas production from permitting under the Safe Drinking Water Act’s (SDWA) Underground Injection Control program. This was because of concern about the risks to drinking water from diesel fuels.
The U.S. Environmental Protection Agency is studying the impacts of hydraulic fracturing on water resources, air quality and the environment and plans to release a report in 2012, with a followup expected in 2014.
The EPA reports that "waste water associated with shale gas extraction can contain high levels of total dissolved solids, fracturing fluid additives, metals, and naturally occurring radioactive materials."
The most common disposal method of the large volume of wastewater is underground injection, but there are reports of this causing earthquakes in Oklahoma and Ohio. The EPA and states say they are studying these and other disposal methods to see if new regulations on disposal are necessary.