A new study estimates that fluids used in the hydraulic fracturing of natural gas in the Marcellus Shale region can migrate into underground drinking water supplies far more quickly than experts have previously estimated. The study, based on computer modeling and funded by opponents of fracking, concluded that natural faults and fractures in the Marcellus shale, exacerbated by the effects of hydraulic fracturing, or “fracking,” could allow chemicals to reach shallow drinking water supplies in as little as “just a few years.” Companies involved in fracking for natural gas have maintained that impermeable layers of rock in the Marcellus Shale formation would keep fracking fluids safely locked nearly a mile below water supplies. But independent hydrologist Tom Myers, who published his study in the journal Ground Water, says his modeling shows that is not the case. “Simply put, [the rock layers] are not impermeable,” said Myers. The Marcellus Shale underlies large portions of the northeastern U.S., and thousands of fracking wells have been drilled in recent years. The study was funded by two organizations opposed to gas fracking, and some scientists strongly disagree with its conclusions.