As the level of hydraulic fracturing of oil and gas wells in the United States has intensified in recent years, much of the mounting public concern has centered on fears that underground water supplies could be contaminated with the toxic chemicals used in the well-stimulation technique that cracks rock formations and releases trapped oil and gas. But in some parts of the country, worries are also growing about fracking’s effect on water supply, as the water-intensive process stirs competition for the resources already stretched thin by drought or other factors.

Every fracking job requires 2 million to 4 million gallons of water, according to the Groundwater Protection Council. The Environmental Protection Agency, or EPA, has estimated that the 35,000 oil and gas wells used for fracking consume between 70 billion and 140 billion gallons of water each year. That’s about equal, EPA says, to the water use in 40 to 80 cities with populations of 50,000 people, or one to two cities with a population of 2.5 million each.

Some of the most intensive oil and gas development in the nation is occurring in regions where water is already at a premium. A paper published last month by Ceres, a nonprofit that works on sustainability issues, looked at 25,000 shale oil and shale gas wells in operation and monitored by an industry-tied reporting website called FracFocus.

Ceres found that 47 percent of these wells were in areas “with high or extremely high water stress” because of large withdrawals for use by industry, agriculture, and municipalities. In Colorado, for example, 92 percent of the wells were in extremely high water-stress areas, and in Texas more than half were in high or extremely high water-stress areas.

“Given projected sharp increases in production in the coming years and the potentially intense nature of local water demands, competition and conflicts over water should be a growing concern for companies, policymakers and investors,” the Ceres report concluded. It goes on to say that:

Prolonged drought conditions in many parts of Texas and Colorado last summer created increased competition and conflict between farmers, communities and energy developers, which is only likely to continue. … Even in wetter regions of the northeast United States, dozens of water permits granted to operators had to be withdrawn last summer due to low levels in environmentally vulnerable headwater streams.

Another recent study by the University of Texas looked at past and projected water use for fracking in the Barnett, Eagle Ford, and Haynesville shale plays in Texas, and found that fracking in 2011 was using more than twice as much water in the state as it was three years earlier. In Dimmit County, home to the Eagle Ford shale development in South Texas, fracking accounted for nearly a quarter of overall water consumption in 2011 and is expected to grow to a third in a few years, according to the study.

Moreover, an April report by the Western Organization of Resource Councils found that fracking is using 7 billion gallons of water a year in four western states: Wyoming, Colorado, Montana, and North Dakota. “Fracking’s growing demand for water can threaten availability of water for agriculture and western rural communities,” said Bob Leresche, a Wyoming resident and board member of the group.

The national oil and gas trade association, American Petroleum Institute, correctly notes that the “industry’s water use is small when compared to other industrial and recreational activities.” But even though hydraulic fracturing usually accounts for just 1 percent or 2 percent of states’ overall water use, the Ceres study notes that “it can be much higher at the local level, increasing competition for scarce supplies.”

New ways to frack

Not surprisingly, the oil and gas industry, along with companies drawn by the opportunity to profit from a better way to frack, are all seeking ways to reduce and even eliminate fracking’s thirst.

A new company in Texas, Alpha Reclaim Technology, sees using treated wastewater from municipal sewage-treatment plants as part of the answer. Founded in 2011, the company has signed up cities to provide about 21 million gallons of treated wastewater a day and is negotiating with oil and gas exploration and production companies to make the switch in the Eagle Ford shale play.

With regard to water use and fracking, Jeremy Osborne, the company’s vice president and general counsel, says, “We are really in a collision course here in Texas”—a course he says is accelerated by drought and population growth.

But Jillian Ryan, Alpha Reclaim Technology’s vice president for government affairs, said changing longstanding practices in the oil and gas industry can be a challenge. While the industry talks a good game about conserving water, Ryan says, “We can have a hard time getting oil and gas companies to live up to what they are talking about. Nobody wants to change. It’s easier to drill a water well where they are drilling [for oil and gas].”

Another player in this oil and gas niche is GASFRAC Energy Services, a Canadian company that says it has successfully fracked about 2,000 wells using liquid propane gas in place of water. Most of these wells are in Canada, but about 100 of them are in Texas.

Environmentalists and fracking critics, however, are alarmed at the thought of fracking with propane. Prompted by the possibility that GASFRAC would be employed in New York state and could evade a state moratorium on fracking by using propane instead of water, environmental groups, including the Sierra Club and the Natural Resources Defense Council, protested to the commissioner of the state’s Department of Environmental Conservation. Similar to water-based fracking, the groups said, fracking with propane also requires “the addition of toxic chemicals.” Because GASFRAC’s method is proprietary, the groups said in their letter that “there is little publicly-available information on the process” and the exact chemicals it uses.

Propane is also very flammable, and in two cases in Alberta in 2011, fires broke out during GASFRAC fracking operations, injuring a total of 15 workers.

Cornell University engineering professor Anthony Ingraffea is among those who are very skeptical of fracking in shale formations with propane and other alternatives to water. Ingraffea has been studying fracturing since doing research for his doctorate in the 1970s. He finds that even modern fracking practices, using millions of gallons of water per well to yield what he says is just 10 percent to 15 percent of oil and gas out, are “very inefficient and inelegant.”

Using propane or a propane-butane combination, Ingraffea says, has a positive side in that it eliminates a key problem with water-based fracking: the disposal of vast quantities of flowback water that returns to the surface after fracking is completed and is often contaminated with things such as salts and radioactivity.

But, he added, no one has yet clearly demonstrated that fracking with propane or some of the other alternatives—such as using a nitrogen or carbon dioxide gel—can compete on economics with water. Propane, he said, “is expensive and nobody really knows how much it takes to develop a typical shale gas well with a lateral that is a mile or two long.”

Oil and gas service companies such as Halliburton and Schlumberger have thrown a lot of money and bright minds at seeking efficiencies over many years, said Ingraffea, and if there was a “silver bullet you would think those companies would have hit it very hard.”

As the Ceres report concludes: