Researchers at the University of Texas – Arlington (UTA) this week released a study entitled “A Comprehensive Analysis of Groundwater in the Barnett Shale Region.” The authors speculate that oil and gas development is one possible cause of elevated levels of contaminants in some water wells in the region, even though they specifically state in the report that their data don’t demonstrate this.
The anti-fracking activist group Earthworks immediately blasted out a press release with the fear-mongering headline “UT study shows widespread groundwater pollution from fracking chemicals.”
The study, however, did not claim to find contamination caused by fracking. The authors clearly conclude:
“The detection of numerous volatile organic compounds in aquifers above the Barnett shale does not necessarily implicate unconventional UOG extraction as the source of contamination; however, it does provide an impetus for further monitoring and analysis of groundwater quality in this region.” (p. 18) [emphasis added]
Perhaps that is why Earthworks (whose Texas representative recently compared fracking – a routine well-completion technique used for more than 60 years – to rape) had to include the disclaimer that the study’s primary author, Dr. Zachariah Hildenbrand, does not endorse the activist press release.
This study is an update to a 2013 study by the same researchers that actually concluded that “natural gas activities do not result in systemic contamination of groundwater.” There is nothing in the updated data to contradict this conclusion.
While this report adds to the body of data on water quality in North Texas, there are a few important facts to consider when evaluating the extent of the report’s utility.
Fact #1: Researchers did not engage in random sampling or include baseline data
The study consisted of an analysis of groundwater sampled collected from 550 private and public supply water wells drawing from aquifers located above the Barnett Shale. The study was necessarily limited in its methodology by biased sampling, which the authors concede. EID has previously reported on this and other limitations found in this study and its predecessor.
Per the study:
“Of the 550 samples, 339 (61.6%) were collected from water wells within 1 km of the nearest UOG well, which likely reflects the increased willingness of well owners to participate in this research in more heavily drilled areas. Unfortunately, this opportunistic and necessarily biased sampling hindered our ability to make meaningful inferences regarding levels of contamination as a function of distance from nearest UOG well for several reasons: (1) the expectation of no detection of a given contaminant for a given sample well assumes uniform and substantial sampling across a gradient of distances from UOG wells, but the distribution of well samples as a function of distance from UOG well was strongly right-skewed; (2) the radius of 1 km for the majority of our groundwater samples is not an adequate distance to detect meaningful statistical patterns of contaminant diffusion from the site of UOG wells; and (3) distance to nearest UOG well is positively correlated with depth of groundwater well (r = 0.36, p < 0.0001) (SI Figure 1), a potential confounding variable (see water quality results below).” (p. 8) [emphasis added]
The study also suffers from a lack of baseline data, which is a major reason that the detection of VOCs in any given well does not necessarily implicate UOG extraction, or hydraulic fracturing, as the source of contamination. In fact, the authors suggest that agricultural activities are likely to be the cause of contamination in some parts of the Barnett Shale as well as noting:
“This region includes a portion of the Dallas-Fort Worth metropolitan area and outlying areas, and groundwater is potentially vulnerable to contamination from various urban and rural sources.” (p. 3)
A lack of baseline data, however, means that the authors cannot legitimately correlate their findings with anything, whether natural gas wells or agriculture or anything else.
Fact #2: Leaves out data on VOC concentrations
The authors also didn’t show the levels of VOC concentrations they found. We simply do not know if they were insignificant trace amounts or something more. The researchers also examined wells outside of the Barnett Shale region. It would be valuable to know what they found there, because if they found BTEX and other compounds there as well, that would indicate that what they found is naturally caused or has a cause other than oil and gas development.
Fact #3: Relies on questionable research
Also troubling is that the authors repeatedly cite, uncritically, research by Duke University’s Avner Vengosh and Rob Jackson on methane concentrations in water wells based on their proximity to oil and gas wells, which subsequent research has shown to be deeply flawed. It is also of concern that the UTA cite a thoroughly discredited study by Anthony Ingraffea of Cornell claiming a 12 percent failure rate of wells in their first year of operation.
Fact #4: EPA’s recent groundwater study found no widespread, systemic impacts to groundwater
The Environmental Protection Agency (EPA) recently released 1,000 page, five-year study on water quality. The EPA noted that there are (non-fracking) mechanisms by which fluids associated with well stimulation could potentially impact groundwater, but these involve issues not directly part of the fracking process, like well casing failure, which the authors of the UTA study claim occurs at a rate of 3 percent but which the Groundwater Protection Council has calculated happens closer to .01 percent of the time.
None of this is to imply that UTA’s most recent study does not add to the body of knowledge about water quality and the Barnett Shale. However, the study is not an indictment of oil and gas development, something the authors take pains to emphasize and activist groups choose to ignore for ideological reasons.