In this March 29, 2013 photo, workers tend to a well head during a hydraulic fracturing operation at an Encana Oil & Gas Inc. gas well outside Rifle, Colorado.
In this March 29, 2013 photo, workers tend to a well head during a hydraulic fracturing operation at an Encana Oil & Gas Inc. gas well outside Rifle, Colorado. Brennan Linsley AP
In this March 29, 2013 photo, workers tend to a well head during a hydraulic fracturing operation at an Encana Oil & Gas Inc. gas well outside Rifle, Colorado. Brennan Linsley AP