From the Denver Business Journal (Cathy Proctor):
“In relative terms, the amount of water used for hydraulic fracturing is a very small percentage of the water that’s used in the state of Colorado — most of it is used for agriculture,” said David Neslin, the director of the Colorado Oil & Gas Conservation Commission, which regulates industry activities in the state.
The report — “Water Source and Demand for the Hydraulic Fracturing of Oil and Gas Wells in Colorado from 2010 through 2015,” available for download here — cautioned that predicting water use related to oil and gas operations is difficult.