In this March 25, 2014 photo, a worker walks among huge pumps and other equipment at the site of a hydraulic fracturing operation at an Encana Corp. well pad near Mead, Colo. The first experimental ... more 
In this March 25, 2014 photo, a worker walks among huge pumps and other equipment at the site of a hydraulic fracturing operation at an Encana Corp. well pad near Mead, Colo. The first experimental use of hydraulic fracturing was in 1947, and more than 1 million U.S. oil and gas wells have been fracked since, according to the American Petroleum Institute. The National Petroleum Council estimates that up to 80 percent of natural gas wells drilled in the next decade will require hydraulic fracturing. (AP Photo/Brennan Linsley) less 
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Associated Press | Photo By Brennan Linsley
Thu, Apr 17, 2014 10:09 AM EDT