New evidence suggests that fracking, which has already been shown to pollute groundwater in some instances, could impact the quality of surface water as well.
The study from scientists at the University of Chicago found that hydraulic fracturing (fracking) is associated with small increases in salt concentrations in surface waters for several shales and many watersheds across the US.
The largest impacts occurred during the early phases of production when wells generated large amounts of flowback and produced water, although even the highest levels of contaminant were well below what the US 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 US shales,” said Christian Leuz, co-author of the study.
“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.”
The team combined surface water measurements with the locations of more than 46,000 fracking wells to examine whether new drilling and development activities are associated with elevated concentrations of salts like bromide, chloride, barium and strontium.
The data, which covers an 11-year period, showed a very small but consistent increase in the salts, except for bromide, in watersheds with new fracking wells.
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 15km and 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,” said co-author Pietro Bonetti.
Fracking fluids contain chemical substances that are potentially more dangerous than salts but they’re not widely included in public databases. This makes it difficult to conduct a large-sample statistical analysis of how polluting they may be. 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,” co-author Giovanna Michelon said.
“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.”
In 2019, the UK imposed a fracking ban after a report from the Oil and Gas Authority concluded that it was not possible with current technology to accurately predict the probability of tremors associated with fracking.
In April, the Climate Change Committee urged the government to continue the ban indefinitely in order to help the UK stick to its climate change commitments.
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