Natural Gas Extraction - Hydraulic Fracturing

Natural gas burner and juxtaposed slate or shale rock

EPA Study of the Potential Impacts of Hydraulic Fracturing on Drinking Water Resources

EPA is conducting a study to better understand any potential impacts of hydraulic fracturing on drinking water and ground water. The scope of the research includes the full lifespan of water in hydraulic fracturing.  You can learn more about the study at epa.gov/hfstudy.

Natural gas plays a key role in our nation's clean energy future. The U.S. has vast reserves of natural gas that are commercially viable as a result of advances in horizontal drilling and hydraulic fracturing technologies enabling greater access to gas in shale formations. Responsible development of America's shale gas resources offers important economic, energy security, and environmental benefits.

EPA is working with states and other key stakeholders to help ensure that natural gas extraction does not come at the expense of public health and the environment. The Agency's focus and obligations under the law are to provide oversight, guidance and, where appropriate, rulemaking that achieve the best possible protections for the air, water and land where Americans live, work and play. The Agency is investing in improving our scientific understanding of hydraulic fracturing, providing regulatory clarity with respect to existing laws, and using existing authorities where appropriate to enhance health and environmental safeguards.

On this page:


Improving our Scientific Understanding of Hydraulic Fracturing

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Providing Regulatory Clarity and Protections against Known Risks

Although the national study should enhance our scientific knowledge, some concerns associated with overall natural gas and shale gas extraction, including hydraulic fracturing, are already well known. These operations can result in a number of potential impacts to the environment, including:
  • Stress on surface water and ground water supplies from the withdrawal of large volumes of water used in drilling and hydraulic fracturing;
  • Contamination of underground sources of drinking water and surface waters resulting from spills, faulty well construction, or by other means;
  • Adverse impacts from discharges into surface waters or from disposal into underground injection wells; and
  • Air pollution resulting from the release of volatile organic compounds, hazardous air pollutants, and greenhouse gases.

Because natural gas development is increasing rapidly in many regions, prudent steps to reduce these impacts are essential now even as further research to understand potential risks continues. EPA is:

Ensuring that hydraulic fracturing using diesel fuels is properly permitted

A core element of the Safe Drinking Water Act's (SDWA) Underground Injection Control (UIC) program is setting requirements for proper well siting, construction, and operation to minimize risks to underground sources of drinking water. The Energy Policy Act of 2005 excluded hydraulic fracturing, except when diesel fuels are used, for oil, gas or geothermal production from regulation under the UIC program. This statutory language caused regulators and the regulated community alike to raise questions about the applicability of permitting practices.

EPA has developed revised UIC Class II permitting guidance specific to oil and gas hydraulic fracturing activities using diesel fuels.  Although developed specifically for hydraulic fracturing where diesel fuels are used, many of the guidance’s recommended practices are consistent with best practices for hydraulic fracturing in general, including those found in state regulations and model guidelines for hydraulic fracturing developed by industry and stakeholders.  Thus, states and tribes responsible for issuing permits and/or updating regulations for hydraulic fracturing will find the recommendations useful in improving the protection of underground sources of drinking water and public health wherever hydraulic fracturing occurs.

EPA is issuing the guidance alongside an interpretive memorandum, which clarifies that Class II UIC requirements apply to hydraulic fracturing activities using diesel fuels, and defines the statutory term “diesel fuel” by reference to five chemical abstract services registry numbers. The guidance outlines for EPA permit writers, where EPA is the permitting authority, (i) existing Class II requirements for diesel fuels used for hydraulic fracturing wells, and (ii) technical recommendations for permitting those wells consistently with these requirements.

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Ensuring the safe disposal of wastewater, stormwater, and other wastes from hydraulic fracturing activities

As the number of shale gas wells in the U.S. increases, so too does the volume of shale gas wastewater that requires disposal. Wastewater associated with shale gas extraction can contain high levels of total dissolved solids (TDS), fracturing fluid additives, metals, and naturally occurring radioactive materials. In partnership with states, EPA is examining the different disposal methods employed by industry to ensure that there are regulatory and permitting frameworks in place to provide safe and legal options for disposal of flowback and produced water. These options include:

Underground injection of waste disposal fluids from oil and gas wells (Class II wells)

In many regions of the U.S., underground injection is the most common method of disposing of fluids or other substances from shale gas extraction operations. Disposal of flowback and produced water via underground injection is regulated under the Safe Drinking Water Act's Underground Injection Control (UIC) program.

Related study: 2004 EPA study evaluating the impacts to underground sources of drinking water by hydraulic fracturing of coalbed methane reservoirs

Wastewater discharges to treatment facilities

The Clean Water Act (CWA) effluent guidelines program sets national standards for industrial wastewater discharges based on best available technologies that are economically achievable. Except in limited circumstances, effluent guidelines for oil and gas extraction prohibit the on-site direct discharge of wastewater from shale gas extraction into waters of the U.S. While some of the wastewater from shale gas extraction is reused or re-injected, a significant amount still requires disposal. However, no comprehensive set of national standards exists at this time for the disposal of wastewater discharged from natural gas extraction activities. As a result, some shale gas wastewater is transported to treatment plants (publicly owned treatment works (POTWs)) or private centralized waste treatment facilities (CWTs)), many of which are not properly equipped to treat this type of wastewater.

In October 2011, as part of the CWA section 304(m) planning process, EPA announced a schedule to develop standards for wastewater discharges produced by natural gas extraction from underground coalbed and shale formations. To ensure that these wastewaters receive proper treatment and can be properly handled by treatment plants, we will gather data; consult with stakeholders, including ongoing consultation with industry; and examine a variety of options for rulemaking. In August 2013, EPA proposed to limit the scope of the rulemaking to standards for wastewater discharges from shale gas extraction, while discontinuing rulemaking for coalbed methane extraction due to declining prevalence and economic viability of coalbed methane extraction. EPA took comment on this approach and expects to make a final decision on wastewater standards for coalbed methane extraction in 2014.

Related study: 2009 coalbed methane extraction sector survey for effluent guidelines program

EPA is also updating chloride water quality criteria for the protection of aquatic life under CWA section 304(a)(1). EPA's recommended Water Quality Criteria are used by states when considering updates to applicable state water quality standards. Such standards provide a basis for establishing acceptable discharge limits. Because flowback and produced water from fracturing operations have very high levels of total dissolved solids (TDS), and chlorides are the major component of the TDS, updating the water quality criteria for chloride will provide an updated scientific basis on which to issue discharge permits. A draft criteria document is expected in late 2014.

In March 2011, EPA issued a set of questions and answers that provide state and federal permitting authorities in the Marcellus Shale region with guidance on permitting treatment and disposal of wastewater from shale gas extraction.

EPA plans to supplement these frequently asked questions with additional guidance directed to permitting authorities, pretreatment control authorities and POTWs. This guidance will provide assistance on how to permit POTWs and CWTs by clarifying existing CWA authorities and obligations.

Stormwater discharges from oil and gas operations or transmission facilities

Under the CWA, oil and gas exploration, production, processing, or treatment operations or transmission facilities, including associated construction activities, are not required to obtain National Pollutant Discharge Elimination System (NPDES) permit coverage for stormwater discharges unless there is a reportable quantity spill or the discharge causes or contributes to a water quality violation.

Use of surface impoundments (pits or ponds) for storage or disposal

In some cases, operators use surface storage tanks and pits to temporarily store hydraulic fracturing fluids for re-use or until arrangements are made for disposal.  In addition, other wastes are generated during the well drilling, stimulation, and production stages. States, tribes, and some local governments have primary responsibility for adopting and implementing programs to ensure proper management of these wastes.

Recycling of wastewater

Some drilling operators elect to re-use a portion of the wastewater to replace and/or supplement fresh water in formulating fracturing fluid for a future well or re-fracturing the same well. Re-use of shale gas wastewater is, in part, dependent on the levels of pollutants in the wastewater and the proximity of other fracturing sites that might re-use the wastewater. This practice has the potential to reduce discharges to treatment facilities or surface waters, minimize underground injection of wastewater and conserve water resources.

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Addressing air quality impacts associated with hydraulic fracturing activities

There have been well-documented air quality impacts in areas with active natural gas development, with increases in emissions of methane, volatile organic compounds (VOCs) and hazardous air pollutants (HAPs). EPA, the Department of the Interior, other federal agencies and states are working to better characterize and reduce these air emissions and their associated impacts. Through the Natural Gas STAR program, EPA and partner companies have identified technologies and practices that can cost-effectively reduce methane emissions from the oil and natural gas sector in the U.S. and abroad. Through the Clean Construction USA program, EPA is promoting newer, more efficient technology and cleaner fuels to innovate the ways in which hydraulic fracturing equipment and vehicles reduce emissions. EPA also administers Clean Air Act regulations for oil and natural gas production, including regulations on reporting greenhouse gas emissions.

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Assuring Compliance

EPA targets enforcement to ensure compliance with laws and regulations, with an emphasis on correcting violations with significant potential harm to human health and the environment. In addition to self-directed investigations, EPA receives thousands of leads and incident reports relating to oil and gas activities that could impact air or water quality. EPA works with state and local governments to respond to incidents, encourage diligent accident prevention, and provide effective and prompt response when emergencies occur. EPA's offices around the nation ("Regions" or "Regional offices") provide guidance and grants to state regulators, perform inspections, conduct enforcement actions, and issue permits and information request letters, in order to ensure that existing laws are effectively implemented.

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Promoting Transparency and Conducting Outreach

Within the federal government, EPA has played a lead role in conducting stakeholder outreach to individual citizens, communities, tribes, state and federal partners, industry, trade associations and environmental organizations that have a strong interest in the Agency's work and policies related to hydraulic fracturing and shale gas extraction. EPA is committed to full transparency and providing opportunities for stakeholder input on all agency actions.

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