As the country awaits results from a nationwide safety study on the natural gas drilling process of fracking, a separate government investigation into contamination in a place where residents have long complained that drilling fouled their water has turned up alarming levels of underground pollution.

A pair of environmental monitoring wells drilled deep into an aquifer in Pavillion, Wyo., contain high levels of cancer-causing compounds and at least one chemical commonly used in hydraulic fracturing, according to new water test results released yesterday by the Environmental Protection Agency.