Hydraulic fracturing, the process of breaking apart rock using pressurized water, sand and chemicals, isn’t out of the spotlight yet, according to Stanford News.

Stanford University environmental scientist Rob Jackson has been researching the effects of shallow fracking on underground water sources. In the study co-authored by Jackson, it was found that 6,900 U.S. oil and gas wells were drilled at depths of less than a mile. Out of those 6,900 wells, 2,600 wells were drilled at less than 1,000 feet.

The impact of fracking on drinking water supplies is one of the key concerns that the team of researchers focused on. Water use is another concern. The research team noted that the oil and gas industry has worked to reuse water for fracking. Out of the shallow wells drilled, some used as much as one million gallons of water. But compared to the amount of water used for coal and nuclear power, fracking uses significantly less water.

In addition to water concerns, the question of fracking techniques and how they might negatively impact the environment in the future was raised.

Via: Stanford News > Shallow fracking raises questions for water, new Stanford research shows