EPA study finds Pavillion’s foul groundwater naturally occurring, not caused by nearby oil and gas activity
December 31, 2019
The Wyoming Department of Environmental Quality released a final report on year’s worth of testing of water wells in the Pavillion, Wyoming area to determine the cause of complaints by residents about reported foul drinking water quality. The report found that the local aquifer contained high amounts of naturally occurring sulfates and related sulfate reducing microbe bioactivity in area water wells rather than contamination by nearby oil and gas drilling activity.
"Geochemical changes associated with the biodegradation of dissolved organic compounds likely have produced constituents associated with poor water palatability, and appear to be linked to declining well yields." The final report was issued by the Wyoming Department of Environmental Quality, Groundwater Section of the Water Quality Division on December 23, 2019.
Residents and well owners have made complaints for nearly a decade to the Wyoming Department of Environmental Quality (WDEQ) about the water quality from the area water well aquifer. The reported changes in water quality from the wells prompted WDEQ to undertake multiple rounds of testing and retesting to assess water quality and identify parameters or conditions that may be causing water well drinking water palatability issues.
The main objective in the review of the data was to investigate if the subsurface microbial community might be causing or contributing to palatability issues in area private groundwater wells. The report confirmed its 2016 findings that groundwater in the Pavillion area has not been contaminated by nearby oil and gas activity or associated hydraulic fracturing methods. Rather, household water has been, in some instances, made toxic by natural gas escaping through porous earth and into groundwater throughout the Upper Wind River Formation. Baseline testing determined the water quality condition existed prior to drilling in the Pavillion area, and is a naturally-occurring condition.
The report found that most of the wells tested in Pavillion draw water from areas in the aquifer that are anaerobic, and since there is a high amount of sulfate in the groundwater, there are degrees of sulfur cycling and sulfur related bioactivity in and around the well bores. The act of drawing water from wells creates an inviting environment for the growth of microbes due to geochemical gradients and nutrient flux. The bacteria in and around the wells, specifically sulfate reducing and oxidizing bacteria, may be contributing to the loss of palatability of the water. The report stated as long as there is no impact on the production of the well (biofouling or aquifer plugging) there is no need to treat or remediate the well itself. Although the well samples indicate the water is not harmful to humans, some residents have been bringing in bottled drinking water rather than drinking the disagreeable tasting well water.
The report says evidence did not indicate that hydraulic fracturing fluids have risen to shallow depths utilized by water-supply wells. The report concludes, based on an evaluation of hydraulic fracturing history and methods used in the Pavillion Gas Field, it is unlikely that hydraulic fracturing has caused any impacts to the water-supply wells.
Click on this link to read the full report (4228 pages) Final Pavillion, Wyoming Gas Field Domestic Water Wells Report on Recommendations for Further Investigation Pavillion, Wyoming
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