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EPA Hydraulic Fracturing Study Finds No Evidence of Widespread Systemic Impacts on Drinking Water Resources

V&E Shale Insights — Tracking Fracking E-communication, June 11, 2015

On June 4, 2015, EPA released its long-anticipated draft assessment of the impacts of hydraulic fracturing operations on drinking water resources. After four years of study, and nearly a thousand pages of analysis, EPA concluded that there was no evidence that these operations have had a “widespread, systemic impact” on surface or groundwater (emphasis added). Notably, EPA did not identify any instances where fluids migrated from the factures made in rock formations more than a mile below the surface up into aquifers that could be potential sources of drinking water. Instead, the draft report concluded that impacts appear to be limited to a small number of water supply wells, relative to the number of hydraulically fractured oil and gas production wells, and as explained below, the impacts do not appear to be specifically related to the injection process. Although EPA emphasized potential gaps in the available data, such as a lack of data associated with potential below-ground impacts and inconsistently collected local water quality data, the draft report indicates that the few instances of documented groundwater impacts were most often the result of surface-level spills or other wastewater treatment issues.

EPA’s assessment focuses on five ways in which hydraulic fracturing operations could affect drinking water resources: (1) water acquisition, (2) chemical mixing, (3) well injection, (4) flowback and produced water, and (5) wastewater treatment and waste disposal. The study focused broadly on all “drinking water resources,” a term which includes any water that could conceivably be used for drinking water at some point in the future, rather than just sources of water that are currently sources of drinking water. As summarized below, the draft assessment found little, if any, support for some of the biggest concerns that critics of hydraulic fracturing typically raise.

Impacts on Water Availability

The draft report stated that hydraulic fracturing operations currently account for less than 1 percent of annual water use in the U.S. In EPA’s view, these operations can have localized impacts on water availability in places with relatively high fracturing water use and low water availability, such as the Eagle Ford Shale in Texas. The draft assessment did not, however, find widespread impacts on the availability of drinking water. The report indicates that about 5 percent of the water currently used in hydraulic fracturing operations is recycled from previous fracturing treatments and that the available data suggests that this percentage is increasing, although the agency’s estimate appears to be low and potentially outdated given other data cited in the draft assessment, such as an estimated 70-90 percent wastewater recycling rate in Pennsylvania.

Water Contamination

EPA found only limited instances where the chemical components of hydraulic fracturing fluids had impacted surface or groundwater. In some instances, hydraulic fracturing fluids or produced flowback wastewater have been spilled on the surface before or after an operation. The data available suggested that such spills are fairly infrequent, with estimates ranging from 0.4 to 12.2 spills of produced water per 100 wells. EPA concluded that these spills stemmed largely from human error, and equipment and container integrity failures.

When these fluids spill on the surface, they can potentially reach a body of water either through overland flow, or by migrating from the soil into groundwater. According to the draft assessment, the likelihood that chemicals contained in spilled fluid will impact groundwater is influenced by a number of factors, including the volume, timing, and composition of the spill. Groundwater impacts become more likely as the volume of the spill, the duration of the release, and the concentration of substances in the spilled fluid increase.

The draft assessment also reports findings related to two types of surface spills: spills of fracturing fluids, and spills of produced water. EPA’s study of 151 spills involving fracturing fluid indicated that the fluids reached surface water in only 9 percent of cases, and reached soil in 64 percent of cases. None of the fracturing fluid spills were reported to have reached groundwater. EPA also found that only 8 percent of produced water spills included in its study reached surface water or groundwater. The risks posed by these spills are similar to spills of crude oil or other fluids from traditional oil and gas operations, which also have the potential to affect surface water or groundwater by migrating through soils.

Notably, EPA did not identify any instances where fluids migrated from the factures made in rock formations more than a mile below the surface up into aquifers that could be potential sources of drinking water. This is consistent with several recent university- and government-sponsored studies that have examined the potential vertical migration of fluids from depth to groundwater and reached this same conclusion.

Instead, the draft assessment suggested that there are several other possible avenues for fracturing fluids or produced water to reach drinking water supplies. In the handful of incidents in which EPA reported that subsurface aspects of hydraulic fracturing may have affected a potable aquifer, it appears that well casing failures, rather than the fracturing operation itself, were the cause of the problem. The risk posed by inadequate well casings is already well-understood by operators, and it is not specific to hydraulic fracturing wells. EPA also suggested that there are greater risks from fracturing older wells than from drilling new ones, due to casing degradation and the potential that older wells may not have been designed or tested to present-day specifications. Such findings may be of particular interest to operators since refracturing is expected to increase in the short- to medium-term. The draft assessment also cited unlined wastewater storage pits or inadequate wastewater treatment as possible sources of impacts on drinking water resources.

EPA determined that any risks related to possible drinking water contamination should be assessed on a local or regional, rather than a national, scale. The draft report described how operators use a wide variety of chemicals in different fracturing fluids, and how the use and occurrence of such chemicals differs widely from basin-to-basin and, in some instances, even well-to-well. EPA encouraged use of the hazard evaluation methods it set forth in the draft assessment on a regional or site-specific basis. However, EPA perceives there to be a lack of toxicity information on many of the chemicals used in fracturing fluid that is a key data limitation, contributing to greater uncertainty in any risk assessment.

Wastewater Treatment

The draft report highlighted a number of issues related to current treatment practices for the wastewater that result from hydraulic fracturing operations. Operators currently employ a number of methods of dealing with these fluids. The most common methods include disposal in underground injection wells (UIC) or disposal wells, use of evaporation ponds, treatment at centralized waste treatment (CWT) facilities followed by reuse or by discharge to either surface waters or publicly owned treatment works (POTWs), reuse with minimal or no treatment, and land application or road spreading (typically for dust suppression). Although the degree to which these methods are used varies by region, UICs are the primary method of disposal in most areas. The draft assessment does not address impacts to drinking water resources that might be associated with high volume disposal into these injection wells.

The draft assessment noted that CWTs and POTWs may not be able to remove all of the substances in the wastewater. For example, the draft assessment found that POTWs using basic treatment processes are not designed to effectively reduce total dissolved solids (TDS) concentrations in highly saline wastewater, although they can remove specific constituents such as metals, oil, and grease. CWTs with advanced wastewater treatment options such as reverse osmosis, thermal distillation, or mechanical vapor recompression, are able to reduce TDS concentrations and treat contaminants known to be in hydraulic fracturing wastewater. The draft assessment noted, however, there is limited data on the composition of hydraulic fracturing wastewater, and it is unknown whether advanced treatment systems are effective at removing constituents that are generally not subject to testing. Although EPA found no evidence of radionuclide contamination in drinking water intakes due to inadequately treated hydraulic fracturing wastewater, the draft assessment noted that CWTs and POTWs may not be able to adequately remove these substances.

The concerns related to both disposal wells and the ability of CWTs and POTWs to adequately treat hydraulic fracturing wastewater may lead regulators to take additional measures to encourage water recycling. For example, according to the draft assessment, 70-90 percent of hydraulic fracturing wastewater is currently reused in Pennsylvania. In recent years, Texas and Colorado have also eased regulatory requirements associated with wastewater recycling to encourage broader use of the practice.  


Although EPA declined to state conclusively that the public’s drinking water supplies are not being adversely affected by hydraulic fracturing activities, the draft results of EPA found no evidence of widespread, systemic impacts on drinking water resources in the United States. EPA found no evidence that hydraulic fracturing fluids migrate up from the depths where hydraulic fracturing occurs into the more shallow areas where aquifers are found. Moreover, impacts to soils or groundwater noted in EPA’s study were caused by problems with casing or the management of drilling fluids or produced water on the surface near the drill site, which could happen with any type of E&P activity. In these respects, EPA’s multi-year study is consistent with what the industry has known for some time but fails to note all the many improvements made by industry during the years while EPA was conducting its study. EPA’s failure to identify any significant contamination resulting from hydraulic fracturing activities means that this assessment is not likely to serve as springboard for pervasive federal regulation of hydraulic fracturing.

EPA’s conclusions are not yet final, and the draft assessment remains subject to public review and comment and peer review by EPA’s Science Advisory Board (SAB). EPA will issue a final report following completion of the public comment and SAB review processes.

For further information, please contact Vinson & Elkins lawyers Larry Nettles, Casey Hopkins, or one of the members of V&E's Shale and Fracking practice group.

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This information is provided by Vinson & Elkins LLP for educational and informational purposes only and is not intended, nor should it be construed, as legal advice.