The report provides a synthesis of information on impacts of unconventional oil and gas operations on groundwater and surface water. The report is intended to advance the scientific foundation to help states and others better protect drinking water sources and identify uncertainties and data gaps. The report does not provide a risk assessment, nor does it evaluate best management practices or policy options.
The report identifies certain conditions under which impacts from hydraulic fracturing activities can be more frequent or severe:
- Water withdrawals for hydraulic fracturing in times or areas of low water availability, particularly in areas with limited or declining groundwater resources
- Spills during the handling of hydraulic fracturing fluids and chemicals or produced water that result in large volumes or high concentrations of chemicals reaching groundwater resources
- Injection of hydraulic fracturing fluids into wells with inadequate mechanical integrity, allowing gases or liquids to move to groundwater resources
- Injection of hydraulic fracturing fluids directly into groundwater resources
- Discharge of inadequately treated hydraulic fracturing wastewater to surface water
- Disposal or storage of hydraulic fracturing wastewater in unlined pits resulting in contamination of groundwater resources.
These findings are consistent with the NGWA position paper on hydraulic fracturing, although the EPA report places less emphasis on methane gas leaks along the outside of wellbores (“stray gas”).
The EPA has struggled with expressing the overall conclusion in its findings — from there is “no evidence for widespread, systemic impacts on drinking water resources” in an earlier draft to “hydraulic fracturing activities can impact drinking water resources under some circumstances” in the final version.
Both of these statements are actually consistent with the NGWA position paper, but by themselves in media reporting convey different messages.
The EPA report notes insufficient pre- and post-fracturing data on the quality of drinking water resources and the paucity of long-term systematic studies. The lack of definitive statements, in part, reflects research gaps and monitoring needs. There is a need for sampling conducted closer to well pads, at multiple depths, and over a longer timeframe.
NGWA will host an upcoming workshop, “Groundwater Quality and Unconventional Oil and Gas Development: Current Understanding and Science Needs,” April 25-26, 2017 in Columbus, Ohio. The call for abstracts is open until January 4, 2017.