In spite of all the controversy, not one study published before 2016 on hydraulic fracturing (fracking) finds evidence that the practice causes systemic groundwater contamination. Some instances of methane migration into or brine contamination of groundwater have occurred, but these are largely attributable to poor well design or failed cement or casings. In CoMeta™, the negative general causation risk scores for methane migration and brine contamination hypotheses reflect the absence of science showing that fracking poses systemic risk to groundwater. This evidence points to the need to implement and enforce best practices in fracking rather than a need to reject it outright.
But in early 2016, Dominic DiGiulio and Robert Jackson published a study that revisits the contentious case of Pavillion, Wyoming, and suggests that the risk of groundwater contamination could be higher for shallowly fracked wells.1 In 2011, the U.S. Environmental Protection Agency (EPA) published a draft report linking fracking to groundwater contamination in Pavillion. The report drew sharp criticism from industry; the EPA withdrew from the study and handed it off to the State of Wyoming. DiGiulio was a lead scientist on the original EPA study and later moved to Stanford University. There, he teamed-up with Jackson, a leading researcher in the field and author of an early study highlighting the potential for fracking to cause groundwater contamination.2 Using previously published information from the State of Wyoming, the EPA, and documents obtained from Freedom of Information Act requests, DiGiulio and Jackson conclude that fracking did indeed lead to groundwater contamination in Pavillion: “We have, for the first time, demonstrated impact to USDWs [underground sources of drinking water] as a result of hydraulic fracturing.”
As striking as this finding sounds, it comes with an important caveat: Fracking injections in the Pavillion field occurred between depths of 250 and 2,000 feet, much shallower than the typical depth of 8,000 feet or more. Because the water table can reach to depths of about 1,000 feet, and because hydraulic fractures can propagate as much as 2,000 feet, it should not surprise anyone to learn that fracking in shallow formations can lead to groundwater contamination. Elsewhere, Jackson et al. (2015) show that approximately 6% of hydraulically fractured wells in the United States are shallow enough that fractures may reach groundwater,3 but a focused analysis of these shallow wells has not yet been conducted. While it is possible that shallowly fracked wells are at greater risk for contamination, it remains to be shown. In the meantime, Colorado and Texas have implemented depth-based regulations designed to mitigate the risks of shallow fracking, but whether these regulations work as intended is also not known.
CoMeta will continue to monitor and characterize the science around this and other fracking-related risks to ensure your underwriting strategies are informed by the most up-to-date information available. At present, these early study results suggest that wells fractured at depths of less than 3,000 feet may be at greater risk of causing groundwater contamination.
R.J. Briggs is Praedicat’s Energy Economist.
You can reach R.J. by email at firstname.lastname@example.org