Strong evidence that shale drilling is risky

By Rob Jackson and Avner Vengosh

'Would you drink the water?" Somebody asked us that question after hearing about our team's study showing high levels of methane in well water near natural-gas drilling sites.

Released on Monday, our analysis will surely fuel the debate over whether the United States should pursue natural gas more vigorously as an alternative to oil and coal, whose unfortunate side effects range from Middle Eastern instability to global warming. Proponents of natural gas highlight its domestic abundance and other advantages. Critics cite potential harm to people and the environment.

Our team examined 68 private groundwater wells in Pennsylvania and New York. We found the average methane concentration to be 17 times higher in water wells located within a kilometer of active drilling sites. Some concentrations were dangerously high.

The companies drilling at these sites employ a process called hydraulic fracturing, or "fracking," pumping water, sand, and chemicals deep underground at high pressure. This opens cracks that allow natural gas to flow into the wells. The process now accounts for about 15 percent of natural-gas production, and some estimates see it rising to nearly half of production by 2035.

Some homeowners in drilling areas believe fracking has polluted their drinking water. Our study suggests that some of them may be right, at least in terms of methane contamination. Our results are also relevant to the bigger question of what role shale gas and hydraulic fracturing should play in solving the nation's energy problems.

Natural gas, or methane, is not benign. It's flammable and potentially explosive. In very high concentrations, it can cause asphyxiation. However, there has been little research on its health effects in drinking water, and the federal government doesn't regulate it as a contaminant in public water systems.

So when someone asked us whether we'd drink water from the wells we studied, we thought for a moment and then answered that we would drink it once or twice, and maybe even occasionally. However, we wouldn't feel safe drinking it regularly, and we don't think the region's homeowners should have to.

Environmental scientists often have the unpleasant task of exposing the drawbacks of different technologies, and this study shows one downside of fracking. But other energy resources have drawbacks, too, and in some cases they're big ones.