BOSTON (Reuters) - Fracking by the U.S. oil and gas industry has increased the burden on the nation's water resources, but still accounts for less than 1 percent of America's total industrial water use, according to a paper by researchers at Duke University published on Tuesday.
The controversial extraction method consumed roughly 48 billion gallons of water per year from 2012 to 2014, according to the study published in the journal Environmental Science & Technology Letters, roughly the same amount that flows over Niagara Falls in 18 hours.
The industry produced about the same amount of wastewater over that period, according to the study, titled "Water Footprint of Hydraulic Fracturing."
"While the hydraulic fracturing revolution has increased water use and wastewater production in the United States, its water use and produced water intensity is lower than other energy extraction methods and represents only a fraction of total industrial water use nationwide," according to the paper.
Fracking involves injecting sand, water and chemicals underground to crack open rock formations holding natural gas and oil - a technique that has led to a boom in U.S. production and a slump in world energy prices.
Opponents of the fracking industry say the practice poses a pollution risk to groundwater, stresses available water resources, and can trigger damaging earthquakes. Industry advocates say those fears are overblown.
The Duke study said that fracking used about 248 billion gallons of water between 2005 and 2014 and yielded about 210 billion gallons of wastewater in roughly the same period. Wastewater can be treated and recycled, or disposed of in deep underground caverns.
The study said, however, that the water use accounted for just 0.87 percent of industrial consumption. It said that other energy extraction methods - including conventional oil production, uranium mining and coal mining - used more water and produced more waste per unit of energy.
The fracking industry has been heavily criticized for increasing water demand in parts of the country, particularly in California, which is suffering from a severe drought.
(Writing by Richard Valdmanis; Editing by Leslie Adler)