Study suggests hydraulic fracturing can impact surface water quality
Tens of thousands of hydraulic fracturing wells drilled over the past few years from Pennsylvania to Texas to North Dakota have made unconventional oil and gas production part of everyday life for many Americans. This raises questions about the impacts to local communities and human health. While some studies document that hydraulic fracturing can contaminate groundwater, new evidence shows the practice can also reduce surface water quality
The study, released today in the journal Science, finds hydraulic fracturing is associated with small increases in salt concentrations in surface waters for several shales and many watersheds across the United States. The largest impacts occurred during the early phases of production when wells generate large amounts of flowback and produced water. However, even the highest levels were well below what the U.S. Environmental Protection Agency considers harmful.
"Our work provides the first large-sample evidence showing that hydraulic fracturing is related to the quality of nearby surface waters for several U.S. shales," says Christian Leuz, a co-author of the study and the Joseph Sondheimer Professor of International Economics, Finance and Accounting at the University of Chicago's Booth School of Business. "Though we estimated very small water impact, one has to consider that most measurements were taken in rivers or streams and that the average fracturing well in our dataset was not particularly close to the monitors in the watershed."
Leuz and his co-authors, Pietro Bonetti from the University of Navarra and Giovanna Michelon from the University of Bristol, combined surface water measurements with more than 46,000 hydraulic fracturing wells to examine whether new drilling and development activities are associated with elevated salt concentrations (bromide, chloride, barium and strontium) in 408 watersheds over an eleven-year period. They found a very small but consistent increase in barium, chloride and strontium, but not bromide, in watersheds with new hydraulic fracturing wells.
Several findings support the connection between the elevated salt levels and the nearby hydraulic fracturing activities. Along with the timing of when the highest levels occurred, the salt concentrations were also more pronounced for wells in areas where the deep formations exhibited higher levels of salinity. Additionally, they were highest when observed within a year at monitoring stations that were within 15 kilometers and (likely) downstream from a well.
"Better and more frequent water measurement is needed to fully understand the surface water impact of unconventional oil and gas development," says Bonetti, who notes that a lack of water quality data limited their analysis.
Hydraulic fracturing fluids contain chemical substances that are potentially more dangerous than salts. But they're not widely included in public databases, making a large-sample statistical analysis of these possibly hazardous substances infeasible. Also, many monitoring stations in a watershed are not located close to wells or may be upstream from the well, likely depressing the magnitude of the estimates.
"Policymakers could consider more targeted water measurement," Michelon says. "For instance, policymakers could place monitoring stations in locations where they can better track surface water impacts, increase the frequency of measurement around the time new wells are drilled, and more systematically track the other chemical substances found in fracking fluids."
Fracking linked to surface water quality for first time in new study
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The effects of fracking on nearby water sources may be worse than previously thought, according to a new study that found hydraulic fracturing can alter the composition of surface water and not just groundwater.
The study, published Thursday in Science, is the first to link fracking to small increases in salt concentrations in surface water, particularly during the early stages of production. While the highest salt levels were well below what the Environmental Protection Agency (EPA) considers harmful, researchers identified a robust association between new wells and water quality changes, triggering public health concerns.
“Our work provides the first large-scale sample evidence showing that hydraulic fracturing is related to the quality of nearby surface waters for several U.S. shales,” Christian Leuz, co-author of the study and a professor at the University of Chicago’s Booth School of Business, said in a news release.
The authors analyzed almost 61,000 surface water measurements that had been taken from 2006 to 2016 near about 46,000 hydraulic fracturing wells across 408 watersheds. They investigated the presence of bromide, chloride, strontium and barium, the ions most common in high concentrations in frack “flowback” — the fluid that returns to the surface following fracking operations. Their findings indicated a small but consistent increase in barium, chloride and strontium, but not in bromide.
While Leuz acknowledged that the concentrations might not be alarming at face value, he warned that measurements taken in rivers are susceptible to considerable dilution. In addition, monitors are sometimes situated a couple miles downstream from a fracking site and across entire watersheds — which can be almost as big as a county, he added.
By averaging data from all the wells throughout such expansive spaces, some of which showed impacts and others of which did not, the researchers ended up with these smaller, but still statistically significant, salt concentrations, according to Leuz.
Higher concentrations of barium in drinking water can lead to increases in blood pressure, while chloride can increase water conductivity — the ability of water to conduct electricity — and lead to unpleasant tasting water, as well as potential threats to aquatic life, according to the U.S. Geological Survey.
Elevated strontium levels can have adverse impacts on bone development.
“They’re not innocuous either,” Leuz told The Hill.
The study identified the highest salt concentrations during the early phases of oil and gas production, when wells generate the most flowback. The researchers also saw higher levels at monitoring stations that were located within 10 miles and downstream from a well, and in measurements taken within a year of the fracking activity.
Co-author Pietro Bonetti, from the University of Navarra in Spain, emphasized the need for more frequent water samples to fully understand the surface water impact, in the news release that accompanied the study. A third co-author, Giovanna Michelon from the University of Bristol in England, called on policymakers to “consider more targeted water measurements” in strategically placed locations.
The three co-authors, who are all economists, became interested in the impacts of hydraulic fracturing on water quality while investigating the ramifications of mandatory chemical disclosure rules that several states — like Wyoming, Pennsylvania and New York — had instituted for hydraulic fracturing operators in 2010. But they first needed to establish a relationship between fracking and surface water quality, which was not yet available, so they implemented their own statistical analysis.
The researchers will conclude a followup study on the effects of disclosure rules in about another month, but Leuz said “the current results suggest that practices became cleaner and had less impact.”
The authors expressed optimism that their statistical approach could be applicable to other fracking chemicals that are even more dangerous than elevated salt levels — but that are rarely included in public databases. For example, recently unearthed documents indicated that the EPA approved the use of fluids that contain toxic forever chemicals.
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If the EPA were to conduct regular measurements on such toxic chemicals and make that data available, Leuz said that he and his colleagues could easily run the same statistical analysis on those compounds.
“We could do this for any substance,” he said. “You give me any relevant chemical, and we could apply this approach.”
Updated: 2:54 p.m.
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