Report: Fracking raising water supply worries

• Hydraulic fracturing adds to water demands in already stressed areas
• Little recycling done to date by producers in Texas%2C report says
• Other evidence points to fracking saving water by reducing reliance on coal

The USA's domestic energy boom is increasing demands on water supplies already under pressure from drought and growing populations, a new report says.

The water-intensive process used to extract oil and gas from shale underground — known as hydraulic fracturing or fracking — has required almost 100 billion gallons of water to drill more than 39,000 oil and shale gas wells in the U.S. since 2011, says Ceres, a green investment group.

More than half of those wells — 55% — were in drought-stricken areas, and nearly half were in regions under high or extremely high water stress, such as Texas, the report says.

To be in extremely high water stress means more than 80% of the area's available surface and ground water is already allocated for city, agriculture or industrial use. High stress means 40% to 80% of the water is already allocated, Ceres says.

Shale development is also occurring rapidly in areas where groundwater is already being depleted by other uses, including agriculture and residential development.

Nationwide, more than 36% of the 39,000 wells drilled since 2011 were in areas already experiencing groundwater depletion, the study says.

Hydraulic fracturing pumps water and chemicals at high pressure to break the shale, allowing trapped oil or gas to flow to the surface.

While fracking consumes far less water than agriculture or residential uses, the impact can be huge on particular communities and is "exacerbating already existing water problems," says Monika Freyman, author of the Ceres study.

Hydraulic fracking is the "latest party to come to the table," Freyman says. The demands for the water are also "taking regions by surprise," she says. More work needs to be done to better manage water use, given competing demands, she says.

Texas has the highest concentration of hydraulic fracturing activity in the U.S. More than half of its wells put in since 2011 were in high or extremely high water stress regions, Ceres says.

In Colorado and California, 97% and 96% respectively of the wells were drilled in regions under high or extremely high water stress.

The oil and gas industry says it's doing more to reuse and recycle water. It also points out that overall water use by the fracking industry is small.

In Colorado, oil and gas development accounts for 0.1% of the state's total water demand, while in Texas, it's less than 1%, says Katie Brown, researcher with Energy in Depth, a research arm of the Independent Petroleum Association of America.

A recent report from the University of Texas also found that natural gas fracking saves water overall by making it easier for utilities to switch from coal to natural gas power. As a result, it's helping to "shield the state from water shortages," Brown says.

More recycling will occur because companies "recognize the economic risk they have," with access to needed water, says Marcus Gay, water research director at IHS Global Insight.

Only about 5% of water consumed by oil and gas producers in the Barnett Shale in North Texas is currently being recycled, says a recent report by research scientist Jean-Philippe Nicot, of the University of Texas. That's probably about average for fracking throughout Texas, Nicot says.

Producers in Pennsylvania, meanwhile, are doing more recycling because they lack good access to deep injection wells to store spent water. For those companies, "it's cheaper to recycle" than ship the water out of state to deep injection wells, Nicot says.