“Keep It In the Ground” activists have claimed for years that hydraulic fracturing (“fracking”) poses an inherent threat to groundwater while deriding those who challenge the claim as “science deniers.” But there is actually no denying the fact that an overwhelming and growing body of scientific evidence shows fracking poses no significant threat to groundwater. No fewer than 29 scientific studies have reached that conclusion.

The current body of research – which includes 15 peer-reviewed papers and eight reports commissioned by regulatory agencies – has examined more than 14,500 water wells across the United States and found no evidence of systemic water contamination issues. Many of the studies examined groundwater pollution and specifically ruled out fracking as the cause. Two of the more than two dozen studies that find no evidence of groundwater impacts from fracking were even partially funded by anti-fracking groups.

Perhaps most notably, a 2016 U.S. Environmental Protection Agency study concluded that, “[H]ydraulic fracturing operations are unlikely to generate sufficient pressure to drive fluids into shallow drinking water zones.” The Obama administration’s EPA reached this conclusion even after expanding the definition of fracking to include virtually every oilfield activity imaginable, thus demonstrating the safety of the entire development process.

As Daniel Raimi, a senior research associate from environmental think tank Resources for the Future, noted in his 2017 book “The Fracking Debate”:

“To date, there is no research that indicates that the health of people living near oil and gas wells has been — or is likely to be — harmed by exposure to the chemicals mixed in with fracking fluid.”

The science is settled – fracking poses no significant threat to groundwater. Here is a review of the scientific research on the subject to date.

Peer-Reviewed Studies

• California Council on Science & Technology (2015): This peer-reviewed independent study by the nonpartisan, not-for-profit CCST and Lawrence Berkeley National Laboratory concluded: “We found no documented instance of hydraulic fracturing or acid stimulations directly causing groundwater contamination in California.” (study link)
• Duke University (2017): Duke researchers evaluated water samples from 112 drinking water wells in West Virginia’s portion of the Marcellus Shale using state-of-the-art isotopic tracers to determine whether or not detected salinity, trace metals and hydrocarbons such as methane were from the fracking process. The researchers concluded, “Based on consistent evidence from comprehensive testing, we found no indication of groundwater contamination over the three-year course of our study.” The study was partially funded by the anti-fracking Natural Resources Defense Council (NRDC). (study link)
• Duke University/United States Geological Survey (2013): Duke and USGS researchers examined the water quality of 127 shallow domestic wells in the Fayetteville Shale and found no evidence of contamination, concluding: “This new study is important in terms of finding no significant effects on groundwater quality from shale gas development within the area of sampling. … Although preproduction water-quality data were lacking for the wells sampled for this study, geochemical data presented a well-defined pattern of geochemical evolution based on natural rock-water and microbially mediated processes, strongly suggesting that the resulting water quality is derived from these natural processes with no effects from gas-production activities.” (study link)
• Gradient (2013): Researchers from environmental risk research firm Gradient released two peer-reviewed studies finding no impacts from shale development. One report states, “Overall, there is no scientific basis for significant upward migration of HF fluid or brine from formations in sedimentary basins. Even if upward migration from a target formation to potable aquifer were hypothetically possible, the rate of migration would be extremely slow and the resulting dilution of the fluids would be very large…Given the overall implausibility and very high dilution factor, this exposure pathway does not pose a threat to drinking water resources.” (study link)
• National Energy Technology Laboratory (2014): In what the Associated Press called a “landmark study,” NETL researchers injected tracers into the hydraulic fracturing fluid in a well in Greene County, Pa., to track for any signs of possible migration. After 12 months of monitoring, the researchers found no signs of this happening. The report concluded: “Current findings are: 1) no evidence of gas migration from the Marcellus Shale; and 2) no evidence of brine migration from the Marcellus Shale.” (study link/alternate link)
• National Groundwater Association (2013): NGA researchers tested 1,701 water wells in northeastern Pennsylvania and found that “methane is ubiquitous in groundwater indicating that, on a regional scale, methane concentrations are not correlated to shale-gas extraction.” (study link)
• Penn State University (2018): PSU researchers analyzed 11,000 groundwater samples collected near 1,385 unconventional natural gas wells in Pennsylvania’s most heavily drilled Marcellus Shale county. The report states that the researchers found “no statistically significant deleterious impact on ten analytes related to the aggressive increase in development of unconventional shale-gas since 2008” and “an overall trend of improving water quality” in Bradford County “despite heavy Marcellus Shale development.” (study link)
• Stanford University (2015): According the report’s press release, “Using innovative techniques such as isotopic ‘tracer’ compounds that distinguish the source of chemicals in well water, [Lead researcher Rob] Jackson has not found evidence that frack water contaminants seep upward to drinking-water aquifers from deep underground.” (study link)
• Syracuse University (2015): SU researchers evaluated 11,309 randomly selected drinking water wells throughout northeastern Pennsylvania and concluded: “There is no significant correlation between dissolved methane concentrations in groundwater and proximity to nearby oil/gas wells.” (study link) 
• University of Cincinnati (2018): UC researchers collected 180 groundwater samples before, during and after drilling was conducted in the most heavily drilled counties in Ohio’s Utica Shale over a four-year period. The researchers concluded, “We found no relationship between CH4 concentration or source in groundwater and proximity to active gas well sites” and noted “… our data do not indicate any intrusion of high conductivity fracking fluids as the number of fracking wells increased in the region.” Notably, the study was partially funded by the anti-fracking David & Sara Weston Foundation and the Deer Creek Foundation. (study link)
• United States Geological Survey (2017): USGS researchers randomly sampled 116 water wells across the Eagle Ford, Fayetteville and Haynesville shale plays and used chemical, isotopic, gas and groundwater-age tracers to thoroughly evaluate those samples. The researchers concluded that low concentrations of methane and benzene detected were likely naturally occurring and not attributable to shale development, and that “UOG [unconventional oil and gas] operations did not contribute substantial amounts of methane or benzene to the sample drinking-water wells.” (study link)
• University of Texas-Austin (2018): UTA researchers evaluated hundreds of water samples from 450 water wells across a 12-county study area located in Texas’s Barnett Shale. They concluded: “[H]ydraulic fracturing [fracking] has not affected shallow groundwater drinking sources in [the Barnett Shale] area.” (study link)
• University of Texas-Austin (2016): UTA researchers evaluated samples from 784 freshwater wells in the Barnett, Haynesville, Eagle Ford and Delaware Basin shale plays in Texas. They found that the presence of high dissolved methane concentrations in the wells “are likely natural” and not related to fracking. (study link)
• Yale University (2018): Yale researchers analyzed eight monitoring wells located in the Marcellus Shale in Susquehanna County, Pa., over a two-year period before, during and after seven shale gas wells were drilled, hydraulically fractured and brought into production. The researchers concluded, “Collectively, our observations suggest that [shale gas development] was an unlikely source of methane in our valley water wells.” (study link)
• Yale University (2015): Yale researchers found no indication of contamination from the fracking process itself in a study area located in the Marcellus Shale in northeastern Pennsylvania. As the researchers explain, “We found no evidence for direct communication with shallow drinking water wells due to upward migration from shale horizons.” (study link)

Government Agency Reports/Evaluations

• Groundwater Protection Council (2011): Based on an evaluation of Texas state data from 1993 to 2008 and Ohio state data from 1983 to 2007, the GWPC report concludes, “Neither state [Ohio and Texas] has documented a single occurrence of groundwater pollution during the site preparation or well stimulation phase of operations.” (report link)
• New York State Department of Environmental Conservation (2011): This NYDEC report states, “A supporting study for this dSGEIS concludes that it is highly unlikely that groundwater contamination would occur by fluids escaping from the wellbore for hydraulic fracturing. The 2009 dSGEIS further observes that regulatory officials from 15 states recently testified that groundwater contamination as a result of the hydraulic fracturing process in the tight formation itself has not occurred.” (report link)
• Susquehanna River Basin Commission (2016): The SRBC analyzed data from July 2008 until December 2013, a period of time when the Marcellus Shale industry was most active in Pennsylvania, and determined, “To date, the Commission’s monitoring programs have not detected discernible impacts on the quality of the Basin’s water resources as a result of natural gas development, but continued vigilance is warranted.” (report link)
• United States Department of Energy (2009): This DOE study, conducted in cooperation with the National Energy Technology Laboratory (NETL) and Groundwater Protection Council (GWPC) concludes, “[B]ased on over sixty years of practical application and a lack of evidence to the contrary, there is nothing to indicate that when coupled with appropriate well construction; the practice of hydraulic fracturing in deep formations endangers ground water. There is also a lack of demonstrated evidence that hydraulic fracturing conducted in many shallower formations presents a substantial risk of endangerment to ground water.” (report link)
• U.S. Environmental Protection Agency (2016): EPA’s six-year study found nothing to suggest that fracking is a serious risk to groundwater. While the agency made some wording changes to its previous topline finding that fracking has not caused “widespread, systemic” impacts to groundwater, the data in the report did not change from the draft version. The report states, “[H]ydraulic fracturing operations are unlikely to generate sufficient pressure to drive fluids into shallow drinking water zones.” (report link)
• United States Geological Survey (2014): The USGS and West Virginia Department of Environmental Protection’s Division of Water and Waste Management compared samples with historical water quality data in an area where drilling and hydraulic fracturing was occurring in the Monogahela River Basin during 2011-12. Researchers found that water quality in the area compared to historical data was not impacted by energy development: “The comparison of groundwater data from this study with historical data found no significant difference for any of the constituents examined and therefore warrant no further discussion.” (report link)
• United States Government Accountability Office (2012): The U.S. GAO consulted regulatory officials in eight states who explained, based on their own state investigations, that “the hydraulic fracturing process has not been identified as a cause of groundwater contamination within their states.” (report link)
• Wyoming Department of Environmental Quality (2019): A six-year-long WDEQ investigation determined that groundwater contamination near Pavillion, Wyo., is not connected to nearby hydraulic fracturing operations, debunking long-held claims to the contrary by anti-fracking groups. The report states: “Evidence does not indicate that hydraulic fracturing fluids have risen to shallow depths utilized by water-supply wells. Also, based on an evaluation of hydraulic fracturing history, and methods used in the Pavillion Gas Field, it is unlikely that hydraulic fracturing has caused any impacts to the water-supply wells.” (report link)

Other Reports

• The Academy of Medicine, Engineering and Science of Texas (2017): This two-year study by TAMEST – which is comprised of academics from a wide range of universities, industry experts and state regulators – analyzed the overall impacts oil and gas development has had on Texas, including water quality, and concluded, “The depth separation between oil-bearing zones and drinking water-bearing zones in Texas makes direct fracturing into drinking water zones unlikely, and it has not been observed in Texas.” (report link)
• Cardno Entrix (2012): This study, focusing on water wells in the Inglewood, Calif., oil field concluded, “Before-and-after monitoring of groundwater quality in monitor wells did not show impacts from high-volume hydraulic fracturing and high-rate gravel packing.” (study link)
• The Center for Rural Pennsylvania (2011): CRP researchers evaluated water sampled from 233 water wells in proximity to Marcellus gas wells in rural regions of Pennsylvania in 2010 and 2011. Among these were treatment sites (water wells sampled before and after gas well drilling nearby) and control sites (water wells sampled though no well drilling occurred nearby). The report concludes, “In this study, statistical analyses of post-drilling versus pre-drilling water chemistry did not suggest major influences from gas well drilling or hydrofracturing (fracking) on nearby water wells, when considering changes in potential pollutants that are most prominent in drilling waste fluids.” (report link)
• German Federal Institute for Geosciences and Natural Resources (2016): In this study, German geologists used computer simulations to study what would happen to frack fluids when injected into the bedrock of the North German basin and found “… that the injected fluids did not move upwards into layers carrying drinking-water.” (study link)
• University of Michigan (2013): This report states that: “The often-postulated percolation upward of fracking water used in deep, long lateral well extensions to contaminate drinking water aquifers near the surface through the intervening impermeable rock formations is highly unlikely and has never reliably been shown to have occurred.” (study link)
•  University of Michigan (2013): Based on meetings between the report’s authors and officials from Arkansas, Colorado, Louisiana, North Dakota, Ohio, Oklahoma, Pennsylvania and Texas, the report states there has been “… no report of groundwater contamination in these states was associated with hydraulic fracturing.” (report link)