Hydraulic fracturing has been used in nearly 1 million wells across the United States. Nonetheless, careful studies by the Environmental Protection Agency and the Ground Water Protection Council haven't revealed a single case of drinking water contamination from shale gas drilling. That's because the fracturing occurs far below the location of drinking water, and the gas wells are encased in steel and concrete to ensure isolation from ground water. All but 1 percent of the fracturing mixture is made up of water and sand, so the small amount of chemicals and additives is well diluted. What's more, as the gas rises to the surface it drives most of the mixture back out of the well, where it can be captured and treated in accordance with state and federal regulations.

Is producing, gathering, processing and delivering natural gas from shale formations completely risk-free? Of course not. Some accidents will happen. But these minimal risks must be weighed against the huge economic and national security benefits that can be realized by fully developing our domestic natural gas resources. Let's not squander this unique opportunity.

http://www.chron.com/disp/story.mpl/editorial/outlook/6768635.html