The problem is not what you've been told.

• Position: Hydraulic Fracturing

Utilizing a new method of geochemical forensics to trace how methane migrates under the earth, a team of researchers uncovered the likely source of most natural gas contamination in drinking-water wells associated with hydraulic fracturing--and it is not the source many people may have feared. What is more, the problem may be fixable: improved construction standards for cement well linings and casings at hydraulic fracturing sites.

The study identified eight clusters of contaminated drinking-water wells in Pennsylvania and Texas. Most important among the findings is that neither horizontal drilling nor hydraulic fracturing of shale deposits seems to have caused any of the natural gas contamination.

"There is no question that, in many instances, elevated levels of natural gas are naturally occurring but, in a subset of cases, there is also clear evidence that there were human causes for the contamination. However, our data suggests that where contamination occurs, it was caused by poor casing and cementing in the wells," says study leader Thomas Darrah, assistant professor of earth sciences at Ohio State University, Columbus, who was aided by researchers from Duke University, Durham, N.C.; Stanford (Calif.) University; Dart mouth College, Hanover, N.H.; and the University of Rochester (N.Y.).

In hydraulic...