One of the issues surrounding development of shale gas resources has been concern over the effects of resource development (especially fracturing processes) on groundwater quality. Congress has initiated an investigation of the practice, for example.
Geoff Styles looks over the issue in “Shale Gas and Drinking Water“, concluding it isn’t likely to be a big deal:
The more I learned about fracking, the more puzzled I became that it has attracted so much criticism recently. After all, the practice was developed in the late 1940s and has been used since then in tens of thousands of wells to produce literally billions of barrels of domestic oil and trillions of cubic feet of domestic natural gas.
… So how do we explain the current ruckus over hydraulic fracturing? Perhaps one reason this old practice is attracting new scrutiny is because it’s being applied in parts of the country that haven’t seen a drilling rig in decades, where it provokes a similar reaction to the arrival of 300-ft. wind turbines, utility-scale solar arrays, and long-distance transmission lines.
The industry doesn’t seem too concerned about the Congressional inquiry, which suggests that folks in the business don’t think that there is anything to be concerned about.