Polar Interpretations of a Study of Shale Gas Development and Surface Water
On Monday, my colleagues, Sheila Olmstead, Jhih-Shyang Shih, Ziyan Chu, Alan Krupnick and I published a paper in the Proceedings of the National Academy of Sciences testing for evidence of impacts to surface water quality from shale gas development across four different pathways. We used more than a decade of data from over 20,000 surface water quality monitors in Pennsylvania and found evidence of an impact from two of the pathways tested, and no evidence from the other two. Interestingly, media outlets chose to highlight very different aspects of these findings. At opposite ends of the spectrum, a Swiss news agency ran a story “Fracking – ein Problem für die Umwelt,” or “Fracking – a problem for the environment,” while the Associated Press ran the story “Pa. water study shows spill concerns small.” What can explain these disparate headlines, if reporters were reading the same study?
We show evidence of the treatment and release of shale gas wastewater into rivers and streams by wastewater treatment plants increases downstream chloride concentrations, basically making the water more salty, (and potentially other contaminants, but the data just aren’t sufficient to check for many other pollutants). Fortunately this practice has been significantly curbed in Pennsylvania due to new regulations and guidelines, but nonetheless for the period of our study, 2000-2011, we did find statistically significant changes in rivers and streams, hence the title “Fracking – a problem for the environment”.
Apart from wastewater treatment facilities, we also looked to see if chloride concentrations were higher downstream of well pads. If we had found evidence of this, it would have been consistent with operators systematically dumping or accidentally spilling wastewater into nearby streams. However, we don’t find any evidence of this, hence the title “Pa. water study shows spill concerns small”. We only show that chloride entered indirectly, via waste treatment plants, not directly via spills.
Another contaminant we looked at was total suspended solids, which is essentially mud and other solids in particles large enough that they don’t dissolve in the water. Our analysis shows that the more well pads there are upstream, the murkier is the water downstream. This finding is most likely driven by the clearing of land and construction activities for well pads and other infrastructure.
We do not find that water is murkier downstream of wastewater treatment plants treating shale gas waste, but this a result to be expected because these plants are built to remove suspended solids (but not most dissolved solids, such as chloride). This result also provides more credence to our finding of a statistically significant increase in chloride downstream of treatment plants treating and releasing shale gas wastewater.
The problem reporters have faced is in finding a one-liner headline for these four important but very different findings, non-contradictory as they are. And our study does not make it easy for them because it is not set up to answer what the ecological or economic implications are of the impacts we do find – our estimates of the impacts on pollutant concentrations are a first step in understanding the impacts of shale gas development on rivers and streams.
Conclusions for now are that states should not expect municipal wastewater treatment plants to be able to treat shale gas wastewater; the ability of industrial wastewater treatment plants to deal with contaminants in this wastewater should be carefully assessed; careful measures should be taken to reduce erosion and sedimentation from shale gas infrastructure sites like well pads and pipelines; and concerned citizens should not worry that most wells are spilling wastewater directly into nearby rivers. Perhaps we should have written four separate papers.