GREELEY, Colo. — A new race for water is rippling through the drought-scorched heartland, pitting farmers against oil and gas interests, driven by new drilling techniques that use powerful streams of water, sand and chemicals to crack the ground and release stores of oil and gas.

A single such well can require five million gallons of water, and energy companies are flocking to water auctions, farm ponds, irrigation ditches and municipal fire hydrants to get what they need.

That thirst is helping to drive an explosion of oil production here, but it is also complicating the long and emotional struggle over who drinks and who does not in the arid and fast-growing West. Farmers and environmental activists say they are worried that deep-pocketed energy companies will have purchase on increasingly scarce water supplies as they drill deep new wells that use the technique of hydraulic fracturing.

http://www.nytimes.com/2012/09/06/us/struggle-for-water-in-colorado-with-rise-in-fracking.html