A year-long, United States Department of Energy study that put tracers in fracking fluids finds that frack fluids are not returning to the surface or groundwater zone but are staying thousands of feet lower.
The study is the first to use tracers and was conducted in Greene County, Pennsylvania. The data is apparently rich, including documenting an 1,800 feet fracture, but has its limits. It is a study of 1 gas drilling site for 1 year.
But this empirical information is consistent with a decades-long record that the threat to groundwater is not from fracking fluids returning from depth. Instead the damage done by gas drilling to water involves spills at the surface, gas migration due to cementing and casing errors, and the disposal of drilling wastewater.
Drilling impacts to water are real and can be reduced by strong regulation and excellent operations. While drilling impacts to water do exist and must be reduced, the harm gas drilling does to water ranks far below coal mining impacts, sewage overflows, oil leaks and spills, nitrogen and phosphorus runoff from land, pollution from impervious surfaces, sediment runoff, and thermal pollution to name a few.