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Image courtesy of the U.S. Geological Survey.

A new study by the U.S. Geologic Survey concluded that hydraulic fracturing activity has not harmed the quality of the groundwater in or around the Bakken shale play.

Scientists compared concentrations of several chemicals and methane in water samples to drinking water standards and analyzed correlations between chemical concentrations and oil and gas well locations.

The study, published in the journal Groundwater, concluded that energy development in the the Williston Basin oil production area of Montana and North Dakota has “not affected shallow groundwater quality.”

“These results are good news for water users, and the data provide a valuable baseline against which future water-quality data can be compared,” USGS hydrologist and lead author of the study Peter McMahon said.

Most of the sampled water was over 1,000 years old and predates oil and gas development in the study area, the USGS said.

The agency said samples taken from shallower wells screened at the water table will provide better information about contamination.

“The groundwater age results indicate that a long-term commitment to monitoring is needed to assess the effects of energy development on groundwater quality in the Williston Basin production area,” McMahon said.

The study was the first comprehensive regional assessment of shallow groundwater quality and age in the Williston Basin production area that includes the Bakken and Three Forks plays.