National Academy of Sciences of the
United States of America
Shale gas development impacts on surface water
quality in Pennsylvania
Concern has been raised in the scientific literature about the
environmental implications of extracting natural gas from deep shale
formations, and published studies suggest that shale gas development
may affect local groundwater quality.
The potential for surface water
quality degradation has been discussed in prior work, although no
empirical analysis of this issue has been published.
The potential for large-scale surface water
quality degradation has affected regulatory approaches to shale gas
development in some US states, despite the dearth of evidence.
This paper conducts a
large-scale examination of the extent to which shale gas development
activities affect surface water quality.
Focusing on the Marcellus Shale
in Pennsylvania, we estimate the effect of shale gas wells and the
release of treated shale gas waste by permitted treatment facilities
on observed downstream concentrations of chloride (Cl−) and total
suspended solids (TSS), controlling for other factors.
Results suggest that (i) the
treatment of shale gas waste by treatment plants in a watershed
raises downstream Cl− concentrations but not TSS concentrations, and
(ii) the presence of shale gas wells in a watershed raises
downstream TSS concentrations but not Cl− concentrations.
These results can inform future
voluntary measures taken by shale gas operators and policy
approaches taken by regulators to protect surface water quality as
the scale of this economically important activity increases.
Sheila M. Olmstead1,
Lucija A. Muehlenbachs,
Ziyan Chu, and
Alan J. Krupnick
Edited by Maureen L. Cropper, University of Maryland, College Park,
MD, and approved January 8, 2013 (received for review August 9,
Proceedings of the National
Academy of Sciences