New evidence suggests that fracking, which has already been shown to pollute groundwater in some cases, may also affect surface water quality.
The study by scientists from 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 in the US.
The greatest effects occurred during the early stages of production, when wells produced large amounts of reflux and produced water, even though even the highest levels of pollutants were well below what the U.S. Environmental Protection Agency considers harmful.
“Our work provides the first large-scale evidence showing hydraulic fracturing is associated with nearby surface water quality for several U.S. shales,” said Christian Leuz, co-author of the study.
“While we estimate a very small water impact, it should be borne in mind that most of the measurements were taken in rivers or streams and that the mean fracture well in our dataset was not particularly close to the monitors in the catchment area.”
The team combined surface water measurements with the locations of more than 46,000 fracking wells to investigate whether new drilling and development activities are associated with elevated concentrations of salts such as bromide, chloride, barium and strontium.
The data, spanning an 11-year period, showed a very small but consistent increase in salts, except bromide, in watersheds with new fracking sources.
In addition to the timing of when the highest levels occurred, the salt concentrations were also more pronounced for wells in areas where the deep formations showed higher salinity. In addition, they were highest when observed within a year at monitoring stations located within 15 km and downstream of a well.
“Better and more frequent water measurements are needed to fully understand the surface water impact of unconventional oil and gas development,” said study co-author Pietro Bonetti.
Fracking fluids contain chemicals that are potentially more dangerous than salts, but they are not widely included in public databases. This makes it difficult to conduct a large-scale statistical analysis of how polluting they can be. Also, many monitoring stations in a catchment area are not located close to wells or upstream of the well, which probably limits the size of the estimates.
“Policymakers could consider a more targeted water measurement,” said study co-author Giovanna Michelon.
“For example, policymakers could place monitoring stations in locations where they can better monitor the effects of surface water, increase monitoring frequency around the time new wells are drilled, and more systematically monitor the other chemicals found in fracking fluids.”
In 2019, the UK imposed a fracking ban after a report from the Oil and Gas Authority concluded that current technology did not allow to accurately predict the likelihood of vibrations associated with fracking.
In April, the Climate Change Committee urged the government to continue the ban indefinitely to help the UK meet its climate change commitments.