Fracking, or hydraulic fracturing, involves the underground injection of water laced with chemicals or other liquids under high pressure – usually through horizontal wells – to break up tight rock formations thousands of metres beneath the surface.
The EPA began analyzing water quality in the city of Pavillion, Wyoming three years ago, after complaints of its water well reeking of chemicals. It found that synthetic chemicals consistent with fracking practices were detected, as well as "well above" safe levels of benzene concentrate and high methane levels. These chemicals were also identified in the city's private and public drinking wells.
Residents have been advised since 2010 to use alternate water sources for drinking and cooking and to have ventilation when showering. Encana, the owner of the gas field, has been paying to provide alternate water supplies.
The EPA says that these findings are consistent with migration from areas of gas production.
The EPA's draft analysis is now subject to public comment and it will be submitted to an independent review panel. It is important to note that these findings are specific to Pavillion, whose fracking conditions are different than others in the continent. The hydraulic fracturing being done is below the drinking water aquifer and is in close proximity to drinking water wells.
The full EPA report on Pavillion, Wyoming is attached below.