US EPA

This assessment provides a review and synthesis of available scientific literature and data to assess the potential for hydraulic fracturing for oil and gas to impact the quality or quantity of drinking water resources, and identifies factors affecting the frequency or severity of any potential impacts. The scope of this assessment is defined by the hydraulic fracturing water cycle which includes five main activities:

1. Water acquisition – the withdrawal of ground or surface water needed for hydraulic fracturing fluids;
2. Chemical mixing – the mixing of water, chemicals, and proppant on the well pad to create the hydraulic fracturing fluid;
3. Well injection – the injection of hydraulic fracturing fluids into the well to fracture the geologic formation;
4. Flowback and Produced water – the return of injected fluid and water produced from the formation to the surface, and subsequent transport for reuse, treatment, or disposal; and
5. Wastewater treatment and waste disposal – the reuse, treatment and release, or disposal of wastewater generated at the well pad, including produced water.

This report can be used by federal, tribal, state, and local officials; industry; and the public to better understand and address vulnerabilities of drinking water resources to hydraulic fracturing activities.

Hydraulic fracturing in combination with advanced directional drilling techniques has made it possible to economically extract oil and gas from unconventional resources, such as shale, tight formations, and coalbeds. The growth in domestic oil and gas exploration and production made possible by the expanded use of hydraulic fracturing, has raised concerns about its potential for impacts to human health and the environment. Specific concerns have been raised by the public about the effects of hydraulic fracturing on the quality and quantity of drinking water resources.

The U.S. Congress urged the U.S. Environmental Protection Agency (EPA) to study the relationship between hydraulic fracturing and drinking water resources. In 2011, the EPA published its Plan to Study the Potential Impacts of Hydraulic Fracturing on Drinking Water Resources. The research described in the Study Plan began the same year and has resulted in 12 EPA reports and several journal publications. This assessment uses the results from EPA-led research projects and the results of hundreds of other publications to provide a synthesis of the science related to hydraulic fracturing and drinking water resources.

To assess the potential impacts of hydraulic fracturing on drinking water resources, if any, and to identify the driving factors that may affect the severity and frequency of such impacts.

The draft assessment was peer reviewed by the EPA’s Science Advisory Board (SAB). The SAB issued their final report on August 11, 2016. The EPA released the final report, Hydraulic Fracturing for Oil and Gas: Impacts from the Hydraulic Fracturing Water Cycle on Drinking Water Resources in the United States, on December 13, 2016.

U.S. EPA. Assessment of the Potential Impacts of Hydraulic Fracturing for Oil and Gas on Drinking Water Resources (External Review Draft). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-15/047, 2015.

Comments on the draft assessment may be submitted and reviewed using the e-Government Regulations.gov Web site. From the site, select “Environmental Protection Agency” and the keyword “EPA-HQ-OA-2015-0245 (for the docket ID) to comment on this report.