Natural Gas Extraction - Hydraulic Fracturing

Natural gas burner and juxtaposed slate or shale rock

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 management 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 salt content also called total dissolved solids or TDS. The wastewater can also contain various organic chemicals, inorganic chemicals, metals, and naturally occurring radioactive materials (also referred to as technologically enhanced naturally occurring radioactive material or TENORM). In partnership with states, EPA is examining the different management 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 to surface waters and municipal sewage treatment plants based on the performance of treatment and control technologies. Effluent guidelines for on-shore oil and gas extraction facilities prohibit the discharge of pollutants into surface waters, except for wastewater that is of good enough quality for use in agricultural and wildlife propagation for those onshore facilities located in the continental United States and west of the 98th meridian. However, those standards do not currently include categorical pretreatment standards for indirect discharges from onshore oil and gas extraction to municipal wastewater treatment plants (also known as publicly owned treatment works or POTWs). 

Historically, operators primarily managed their wastewater via underground injection in disposal wells (where available). Where unconventional oil and gas wells were drilled in areas with limited underground injection wells, and/or there was a lack of wastewater management alternatives, it became more common for operators to look to POTWs and private wastewater treatment facilities to manage their wastewater. Because they are not typical of POTW influent wastewater, some unconventional oil and gas extraction wastewater constituents:

  • Can be discharged, untreated, from the POTW to surface waters
  • Can disrupt the operation of the POTW (for example, by inhibiting biological treatment)
  • Can accumulate in biosolids (also called sewage sludge), limiting their use, and
  • Can facilitate the formation of harmful disinfection by-products.

Proposed rulemaking:  On April 7, 2015, EPA published proposed pretreatment standards for the Oil and Gas Extraction Category (40 CFR Part 435). The regulations would address discharges of wastewater pollutants from onshore unconventional oil and gas (UOG) extraction facilities to POTWs.

Related study of private wastewater treatment facilities:  EPA is conducting a study of private wastewater treatment facilities (also known as centralized waste treatment, or CWT, facilities) accepting oil and gas extraction wastewater. EPA is collecting data and information related to the extent to which CWT facilities accept such wastewater, available treatment technologies (and their associated costs), discharge characteristics, financial characteristics of CWT facilities, the environmental impacts of discharges from CWT facilities, and other relevant information.

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 also committed to promoting informed decision making and transparency regarding chemicals and mixtures used in hydraulic fracturing activities.

  • Hydraulic Fracturing Chemicals and Mixtures.  On May 9, 2014, EPA issued an Advance Notice of Proposed Rulemaking (ANPR) under Section 8 of the Toxic Substances Control Act (TSCA).  The notice will begin the public participation process and seek public comment on:
    • the types of chemical information that could be reported and disclosed under TSCA, and
    • the approaches to obtain this information on chemicals and mixtures used in hydraulic fracturing activities, including non-regulatory approaches.
    This process:
    • will help inform EPA’s efforts to facilitate transparency and public disclosure of chemicals used during hydraulic fracturing and
    • will not duplicate existing reporting requirements.
    The Federal Register published the notice on May 19, 2014.  The comment period is now closed.  On, you can view: You can also: