Shale Gas Development Impacts on Water Quality

Researchers conclude that shale gas wells and the treatment of shale gas  extraction waste have measurable impacts on downstream surface water quality.

GLOBE-Net, June 19, 2013 – The impact of shale gas development on surface water quality has been explored in a recent study. Focusing on the Pennsylvania portion of the Marcellus  Shale formation (which stretches from West Virginia to the Canadian border), the  researchers conclude that shale gas wells and the treatment of shale gas  extraction waste have measurable impacts on downstream surface water quality.

The researchers collected data from over 20,000 water quality observations, between 2000 and 2011, and mapped them. These were then considered in relation to the location of shale  gas wells and information about shale gas waste shipments, using a geographical  information system (GIS). This allowed them to make links between areas of shale gas  development and downstream water quality, using a sophisticated statistical model that  accounted for other factors that might be affecting water quality.

The study revealed that downstream concentrations of chloride increased when there were more wastewater plants treating and releasing shale gas waste in an area. High levels of  chloride can damage aquatic ecosystems, and also trigger the release of other pollutants,  such as heavy metals and phosphates, from sediment. The number of wells themselves did  not seem to affect chloride levels.

On the other hand, there was no increase in suspended solids downstream of wastewater plants treating shale gas waste, but there was an increase of this pollutant downstream of  wells.

Suspended solids include silt, decaying organic matter and industrial waste, which can  also cause ecological problems by clouding water, reducing sunlight, raising water  temperature and reducing oxygen levels. They can also block pipes, leading to financial costs  for downstream water users.

Based on the results, the researchers calculated that for each additional 1.5 facilities treating waste upstream, the downstream water concentrations of chloride increase by 10-11%. For  an additional 18 well pads, they calculated that the downstream suspended solids increase  by 5%.

The researchers stress that their geographical mapping method only models average impacts at a large scale, rather than at a precise, local scale. It is also focused on surface water  rather than groundwater, and does not consider other forms of contamination directly from  wells or shale deposits.

However, they say the results could help inform policy decisions about protecting water quality near shale gas development and waste treatment sites, as well as decisions regarding  well location, waste disposal, erosion control and contaminant monitoring.

To further inform  policy, a better understanding is also needed of the costs associated with the increased  pollution, and of how they compare to the economic benefits of shale gas development.

^{Citation: Olmstead, S.M. Muehlenbachs, L.A., Shih, J-S., Chu, Z., Krupnick, A.J. (2013). Shale gas development impacts on  surface water quality in Pennsylvania. Proceedings of the National Academy of Sciences. DOI: 10.1073/pnas.1213871110  . This study is free to view at: www.pnas.org/content/110 /13/4962.abstract –  “Science  for Environment Policy”:  European Commission DG  Environment News Alert  Service, edited by  SCU, The University of the   West of England, Bristol.}