An EPA report that said fracking was safe is now being disputed by its own scientists

REUTERS/Peter Andrews

A fracking rig.

An Environmental Protection Agency report released in June on the impacts of fracking on water quality is now being called into question - by none other than the agency's own scientists.

The report initially did not find "widespread, systemic impacts" on drinking water resources close to fracking sites. But the EPA's Science Advisory Board responded in December, after the report was released, that "major findings are ambiguous or inconsistent with the observations/data presented in this report," according to Bloomberg.

The controversy rests on one key aspect of the report's findings. It states that the "...number of identified cases [of contaminated wells], however, was small compared to the number of hydraulically fractured wells."

While this may be accurate, the report goes on to admit that insufficient long-term data on pre and post fracking water quality could have limited their results, and may not explicitly point to the "rarity of effects on drinking water resources."

It's this paucity of information that gives some of the reviewing scientists pause: "I do not think that the document's authors have gone far enough to emphasize how preliminary these key conclusions are and how limited the factual bases are for their judgments," James Bruckner, a member of the Science Advisory Board, told Bloomberg.

Members of the Science Advisory Board, as well as environmental advocates, are also pushing the EPA to include more detailed analysis of the severity of alleged instances of contamination near drilling sites.

Though the Board's reccommendations aren't binding, the EPA will "evaluate" possible changes to the report, according to Bloomberg.

Hydraulic fracturing, or fracking, is a method used to release oil and natural gas from tight rock formations deep underground. Fluids are injected deep into the earth at pressures high enough to fracture the rock surrounding the oil and natural gas deposits, allowing the fuel a clear path to the surface.

The fluids - toxic slurries of water and volatile organic compounds like benzene - are the primary cause of health impacts when they leach into groundwater supplies used for drinking due to improper storage, disposal, or work-site accidents.