Environmental impact of fracking in the United States has been an issue of public concern, and includes the contamination of ground and surface water, methane emissions, air pollution, migration of gases and fracking chemicals and radionuclides to the surface, the potential mishandling of solid waste, drill cuttings, increased seismicity and associated effects on human and ecosystem health. Research has determined that human health is affected. A number of instances with groundwater contamination have been documented due to well casing failures and illegal disposal practices, including confirmation of chemical, physical, and psychosocial hazards such as pregnancy and birth outcomes, migraine headaches, chronic rhinosinusitis, severe fatigue, asthma exacerbations, and psychological stress. While opponents of water safety regulation claim fracking has never caused any drinking water contamination, adherence to regulation and safety procedures is required to avoid further negative impacts.
As early as 1987, researchers at the United States Environmental Protection Agency (EPA) expressed concern that fracking might contaminate groundwater. With the growth of fracking in the United States in the following years, concern grew. "Public exposure to the many chemicals involved in energy development is expected to increase over the next few years, with uncertain consequences" wrote science writer Valerie Brown in 2007. It wasn't until 2010 that Congress asked the EPA to conduct a full study of the environmental impact of fracking. The study is ongoing, but the EPA released a progress report in December 2012 and released a final draft assessment report for peer review and comment in June 2015.
Air quality and methane emissions.
Methane emissions from wells raise global warming concerns. There is a 2,500 square-mile methane plume hovering over the Four Corners area of the western US. The magnitude of the plume was such that NASA researcher Christian Frankenberg reported to the press that, "We couldn't be sure that the signal was real." According to NASA: "The study's lead author, Eric Kort of the University of Michigan, Ann Arbor, noted the study period predates the widespread use of fracking near the hot spot. This indicates the methane emissions should not be attributed to fracking but instead to leaks in natural gas production and processing equipment in New Mexico's San Juan Basin, which is the most active coalbed methane production area in the country."
Other concerns are related to emissions from the fracking chemicals and equipment such as volatile organic compound (VOC) and ozone. In 2008, ozone concentrations in ambient air near drilling sites in Sublette County, Wyoming were frequently above the National Ambient Air Quality Standards (NAAQS) of 75 ppb and have been recorded as high as 125 ppb. In DISH, Texas, elevated levels of disulfides, benzene, xylenes and naphthalene have been detected in the air, emitted from compressor stations. In Garfield County, Colorado, an area with a high concentration of drilling rigs, VOC emissions increased 30% between 2004 and 2006.
Researchers from the University of Michigan analyzed the emissions produced from the fracking equipment at the Marcellus Shale and Eagle Ford Shale plays, and concluded that hydraulic pumps accounted for about 83% of the total emissions in the fracking fleet. NOx emission ranged between 3,600 and 5,600 lb/job, HC 232–289 lb/job, CO 859–1416 lb/job, and PM 184–310 lb/job. If the fuel efficiencies of the fracking pumps are improved, the emissions can be reduced.
On April 17, 2012, the EPA issued cost-effective regulations, required by the Clean Air Act, which include the first federal air standards for natural gas wells that are hydraulically fractured. The final rules are expected to yield a nearly 95% reduction in VOC emissions from more than 11,000 new hydraulically fractured gas wells each year. This reduction would be accomplished primarily through capturing natural gas that escapes into the air, and making it available for sale. The rules would also reduce air toxins, which are known or suspected of causing cancer and other serious health effects, and emissions of methane, a potent greenhouse gas.
A study published in the "Proceedings of the National Academy of Sciences" in April 2014 "identified a significant regional flux of methane over a large area of shale gas wells in southwestern Pennsylvania in the Marcellus formation and further identified several pads with high methane emissions. These shale gas pads were identified as in the drilling process, a preproduction stage not previously associated with high methane emissions." The study found that "Large emissions averaging 34 g CH4/s per well were observed from seven well pads determined to be in the drilling phase, 2 to 3 orders of magnitude greater than US Environmental Protection Agency estimates for this operational phase. The emissions from these well pads, representing ~1% of the total number of wells, account for 4–30% of the observed regional flux. More work is needed to determine all of the sources of methane emissions from natural gas production, to ascertain why these emissions occur and to evaluate their climate and atmospheric chemistry impacts."
A two-day airborne survey of fracking sites in southwest Pennsylvania revealed drilling operations releasing plumes of methane 100 to 1,000 times the rate the EPA expects from that stage of drilling.
In 2019, Robert W. Howarth concluded that rising shale-gas production in North America has contributed significantly to the recent increase in global atmospheric methane. The "ideas and perspectives" piece from Howarth is controversial with a critical comment from Lewan (2020) and at odds with other papers including a 2019 review paper on atmospheric methane (Turner et al., PNAS 2019) and two earlier papers using stable isotopes (Schaefer et al., Science 2016; Schwietzke et al., Nature 2016).
Water issues.
2015 EPA Report on Spills.
In May 2015, the EPA released a report reviewing the spill data from various state and industry sources for data about spills related to hydraulic fracturing. Of the total reports reviewed in the study 1% (457) were determined to be related to hydraulic fracturing, while 66% were unrelated and 33% had insufficient data reported to determine if the spill was associated to hydraulic fracturing. In 324 incidents the spilled fluids were reported to reach categorized environmental receptors: Surface Water 67%, Soil 64%, and Ground Water 48%.
Other key spill figures from the report:
This report was cited in the full hydraulic fracturing water report now open for peer review though not directly addressed in the contents of the EPA spill data report. Several times, associations between hydraulic fracturing, causes of spills, and response to spills were unknown or indeterminate because of missing or unreported data. This highlights the need for more complete reporting and standardization of reporting for improved tracking to better guide implementation of environmental safety practices particularly where the impact is likely to impact key health determinants like water quality.
Water usage.
Hydraulic fracturing uses between of water per well, with large projects using up to . Additional water is used when wells are refractured. An average well requires of water over its lifetime. Back in 2008 and 2009 at the beginning of the shale boom in Pennsylvania, hydraulic fracturing accounted for (less than 0.8%) of annual water use in the area overlying the Marcellus Shale. The annual number of well permits, however, increased by a factor of five and the number of well starts increased by a factor of over 17 from 2008 to 2011.
According to Environment America, a federation of state-based, citizen-funded environmental advocacy organizations, there are concerns for farmers competing with oil and gas for water. A report by Ceres questions whether the growth of hydraulic fracturing is sustainable in Texas and Colorado as 92% of Colorado wells were in extremely high water stress regions (that means regions where more than 80% of the available water is already allocated for agricultural, industrial and municipal water use) and 51% percent of the Texas wells were in high or extremely high water stress regions. In Barnhart, Texas the aquifer supplying the local community ran dry because of intensive water utilization for hydraulic fracturing. In 2013, the Railroad Commission of Texas adopted new hydraulic fracturing water recycling rules intended to encourage Texas hydraulic fracturing operators to conserve water used in the hydraulic fracturing process.
Consequences for agriculture have already been observed in North America. In some regions of the US that are vulnerable to droughts, farmers are now competing with fracking industrials for the use of water resources. In the Barnett Shale region, in Texas and New Mexico, drinking water wells have dried up due to fracking's withdrawal of water, and water has been taken from an aquifer used for residential and agricultural use. Farmers have seen their wells go dry in Texas and New Mexico as a result of fracking's pressure on water resources, for instance in Carlsbad, New Mexico. Agricultural communities have already seen water prices rising because of that problem. In the North Water Conservation District in Colorado was organized an auction to allocate water and the prices rose from $22/acre-foot in 2010 to $28 in the beginning of 2012.
Injected fluid.
Hydraulic fracturing fluids include proppants, various chemicals, and sometimes radionuclide tracers. While many are common and generally harmless, some additives used in the United States are known carcinogens. Out of 2,500 hydraulic fracturing products, more than 650 contained known or possible human carcinogens regulated under the Safe Drinking Water Act or listed as hazardous air pollutants". Between 2005 and 2009, 279 products had at least one component listed as "proprietary" or "trade secret" on their Occupational Safety and Health Administration (OSHA) required safety data sheet (SDS). In many instances, companies who bought products off the shelf did not know the ingredients. Without knowing the identity of the proprietary components, regulators cannot test for their presence. This prevents government regulators from establishing baseline levels of the substances prior to hydraulic fracturing and documenting changes in these levels, thereby making it more difficult to prove that hydraulic fracturing is contaminating the environment with these substances.
The Ground Water Protection Council launched FracFocus.org, an online voluntary disclosure database for hydraulic fracturing fluids funded by oil and gas trade groups and the United States Department of Energy (DOE). The site has been met with some scepticism relating to proprietary information that is not included. Some states have mandated fluid disclosure and incorporated FracFocus as the tool for disclosure.
Groundwater contamination.
In-depth research to determine a relation between fracking and groundwater contamination is sparse, but evidence suggests that fracking has contributed to groundwater contamination due to the chemicals used in the procedure of shale drilling; however, since thousands of feet of dirt and rock separate natural gas deposits and groundwater supplies, and other contaminating agents could also contribute, it is difficult to determine an absolute relation between fracking and groundwater contamination.
In 2009, state regulators from across the country stated that they had seen no evidence of hydraulic fracturing contaminating water in their respective jurisdictions. In May 2011 the EPA Administrator Lisa P. Jackson testified in a Senate Hearing Committee stating that the EPA had never made a definitive determination of contamination where the hydraulic fracturing process itself has contaminated water. However, by 2013, Dr. Robin Ikeda, Deputy Director of Noncommunicable Diseases, Injury and Environmental Health at the CDC testified to congress that EPA had documented contamination at several sites.
Flowback and produced water.
Flowback is the portion of the injected fracturing fluid that flows back to the surface, along with oil, gas, and brine, during well commissioning, a process which typically takes a week, though durations vary. An estimated 90% of flowback in the United States is disposed of into deep EPA-licensed Class II disposal wells, with the remaining less than 10% reused, evaporated, used for irrigation, or discharged to surface streams under an NPDES permit. Of nine oil and gas-producing states studied in 2012, underground injection disposal was by far the predominant method in all but Pennsylvania where were only six active waste disposal wells. In California, Virginia, and Ohio there have been instances of illegal dumping of flowback, a precursor to possible contamination of local ground and surface water reservoirs. Discharging oil and gas produced water to surface streams without an NPDES permit is a federal crime. Discharges through water treatment works must comply with the federal Clean Water Act and the terms of their NPDES permits, but the EPA noted that most water treatment works are not set up to treat flowback.
In Pennsylvania, oil and gas produced water had for many years been accepted by licensed water treatment works for treatment and discharge, but the volume expanded greatly with the proliferation of Marcellus Shale wells after 2000. In