The U.S. Environmental Protection Agency (EPA) recently released their “final” report on the impacts of hydraulic fracturing (fracking) on drinking water resources.  This final report follows a draft report on this issue the agency released in June 2015.

The draft report concluded that fracking does not have a widespread systematic adverse impact drinking water supplies.  This finding was roundly criticized by environmental groups, opponents of the oil and gas industry, and by the EPA’s own Science Advisory Board (SAB).  The SAB faulted the agency’s report principally because the main conclusion that there were no systematic effects on drinking water was not well-supported by enough quantitative facts.

Thus the EPA went back to work and produced the 1,238 page final report in December 2016.  In the final report, the statement that fracking does not impact drinking water supplies was taken out.  The EPA found that from 0.1 to 1 percent of wells had lost some integrity, meaning that fracking fluids could escape the well and infiltrate ground water.

While these percentages are small, there are many, many wells being fracked in this country.  The U.S. Energy Information Administration estimated there were 600,000 wells in oil and gas production in 2015.  Environmental groups have reported much higher numbers of wells.  One percent of 600,000 is still 6,000 wells across the county that could be affecting drinking water supplies.

In the final report, EPA identified more than 1600 chemicals that can be present in fracking liquids.  Less than 200 of these have had their toxic effects studied enough to set chronic health risk factors.  For the latter group of chemicals, the agency has developed a ranking scheme to identify those chemicals posing the highest hazards.  This scheme is based on the toxicity of the chemicals, how often the chemical is found in fracking fluids and produced water, and physicochemical properties of the chemical such as mobility in ground water and persistence.

Benzene, acrylamide, and polycyclic aromatic hydrocarbons are the chemicals in fracking fluids and in produced water that had the highest hazard rankings for non-cancer and cancer effects.  One limitation of this report is it is not a human health risk assessment document.  The hazard rankings only identify the chemicals of highest concern.  The human health risk of exposure to these chemicals at the levels expected in fracking-operation-contaminated drinking water has not been determined.

Links to the executive summary, the full final report, and its appendices can be accessed at