The U.S. Environmental Protection Agency found no evidence that hydraulic fracturing caused ground water contamination in a hamlet in rural Pennsylvania.

The finding could be a major impetus to further expansion of the lucrative but controversial practice throughout the country. Hydraulic fracturing, or fracking, is a drilling technique for natural gas in which high volumes of water, chemicals and sand are injected underground to fracture shale rock formations. Natural gas trapped in the rock is released and then extracted.

The EPA investigated claims made by families in Dimock, Pa., a hamlet in northeastern Susquehanna County with a population of 128. Although the families alleged Cabot Oil & Gas Corp. ( COG ) contaminated groundwater to 11 homes, the EPA said the claims were unfounded.