106
Investigations by the USGS of groundwater overlying prominent shale gas and
tight oil production regions in the U.S. found no evidence of widespread aquifer
contamination from fracking, although they did find isolated incidents of groundwater contamination that they concluded were from surface spills. However, many
of the contaminants that were found pre-dated the shale development in the area,
and were from earlier spills or leaks. The USGS studies focused on determining
both the origin of the contaminants and the age of the groundwater (i.e. when it
entered the aquifer as recharge). The two analyses together created a more complete
picture of how and when the aquifer might have been contaminated.
Some notable findings from the series of USGS groundwater studies include the
following: Groundwater methane in the Bakken Shale development region of North
Dakota was sourced primarily from the lignite (brown coal) located high above the
Bakken in the stratigraphic section (McMahon et al. 2015). Other sources of contamination from the long history of oil and gas development in California essentially masked any potential groundwater impairment caused by recent fracking
activities (McMahon et al. 2016). Aquifer studies in Arkansas, Louisiana, and Texas
above the Fayetteville, Haynesville, and Eagle Ford shale plays found that methane
in the groundwater was mostly biogenic in origin (McMahon et al. 2017).
A comparative investigation of aquifers in upland areas across the PennsylvaniaNew York border region found very similar groundwater chemistries among the 50
wells sampled. Marcellus Shale gas is being produced only in Pennsylvania because
New York has a fracking ban in place. One well contained thermogenic methane
from a shallow geological source that may have been mobilized by nearby fracking
activity. Another contained benzene, a component of gasoline, but the water sample
had recharged prior to the beginning of shale gas development in the region, and the
contamination was from an older spill (McMahon et al. 2019).
The largest investigation and review to date on the potential impacts of fracking
on water resources in the United States is a 664 page report published by U.S. EPA
Office of Research and Development in 2016 at the conclusion of a five-year investigation (USEPA 2016). The goal of this study was to assess the risks to groundwater supplies (identified as Underground Sources of Drinking Water or USDW by the
EPA) from hydraulic fracturing operations. The project hosted a number of technical workshops to obtain input from the O&G industry, research scientists from other
federal and state agencies, environmental advocacy groups, and interested citizens.
An extensive compilation of existing scientific literature was gathered up, and a
number of field and laboratory investigations were carried out. The results were
assembled into a nearly 1000-page draft report in 2015 that was published as a final
report a year later after receiving detailed peer reviews. The EPA study concluded
that although fracking can cause individual groundwater contamination incidents,
primarily through surface spills, the evidence did not support concerns that fracking
was systemically contaminating shallow aquifers on a widespread basis. No one so
far has published any data that contradict this.
The EPA study identified 1606 chemicals associated with hydraulic fracturing,
including 1084 chemicals used in hydraulic fracturing fluid and 599 chemicals
detected in produced water (USEPA 2016). Although only about a half-dozen
6 Fracking and Water
Investigations by the USGS of groundwater overlying prominent shale gas and
tight oil production regions in the U.S. found no evidence of widespread aquifer
contamination from fracking, although they did find isolated incidents of groundwater contamination that they concluded were from surface spills. However, many
of the contaminants that were found pre-dated the shale development in the area,
and were from earlier spills or leaks. The USGS studies focused on determining
both the origin of the contaminants and the age of the groundwater (i.e. when it
entered the aquifer as recharge). The two analyses together created a more complete
picture of how and when the aquifer might have been contaminated.
Some notable findings from the series of USGS groundwater studies include the
following: Groundwater methane in the Bakken Shale development region of North
Dakota was sourced primarily from the lignite (brown coal) located high above the
Bakken in the stratigraphic section (McMahon et al. 2015). Other sources of contamination from the long history of oil and gas development in California essentially masked any potential groundwater impairment caused by recent fracking
activities (McMahon et al. 2016). Aquifer studies in Arkansas, Louisiana, and Texas
above the Fayetteville, Haynesville, and Eagle Ford shale plays found that methane
in the groundwater was mostly biogenic in origin (McMahon et al. 2017).
A comparative investigation of aquifers in upland areas across the PennsylvaniaNew York border region found very similar groundwater chemistries among the 50
wells sampled. Marcellus Shale gas is being produced only in Pennsylvania because
New York has a fracking ban in place. One well contained thermogenic methane
from a shallow geological source that may have been mobilized by nearby fracking
activity. Another contained benzene, a component of gasoline, but the water sample
had recharged prior to the beginning of shale gas development in the region, and the
contamination was from an older spill (McMahon et al. 2019).
The largest investigation and review to date on the potential impacts of fracking
on water resources in the United States is a 664 page report published by U.S. EPA
Office of Research and Development in 2016 at the conclusion of a five-year investigation (USEPA 2016). The goal of this study was to assess the risks to groundwater supplies (identified as Underground Sources of Drinking Water or USDW by the
EPA) from hydraulic fracturing operations. The project hosted a number of technical workshops to obtain input from the O&G industry, research scientists from other
federal and state agencies, environmental advocacy groups, and interested citizens.
An extensive compilation of existing scientific literature was gathered up, and a
number of field and laboratory investigations were carried out. The results were
assembled into a nearly 1000-page draft report in 2015 that was published as a final
report a year later after receiving detailed peer reviews. The EPA study concluded
that although fracking can cause individual groundwater contamination incidents,
primarily through surface spills, the evidence did not support concerns that fracking
was systemically contaminating shallow aquifers on a widespread basis. No one so
far has published any data that contradict this.
The EPA study identified 1606 chemicals associated with hydraulic fracturing,
including 1084 chemicals used in hydraulic fracturing fluid and 599 chemicals
detected in produced water (USEPA 2016). Although only about a half-dozen
6 Fracking and Water