Development of shale gas resources relies on water for drilling, hydraulic stimulation, and for the dilution and treatment of waste waters. In some shale gas plays, freshwater used to support natural gas extraction is withdrawn from streams and rivers. These withdrawals have the potential to significantly lower stream flows, which, in turn, may degrade stream habitat, alter stream water chemistry and temperature, and reduce the capacity of streams to assimilate pollutants. In this work, we characterize the appropriation of surface water for the extraction of natural gas from Pennsylvania’s Marcellus Shale, and we examine the influences of these withdrawals on natural stream flows. Our analysis reveals that approximately 300 sites along Pennsylvania’s streams and rivers have been permitted to supply freshwater in support of shale gas development. These withdrawal sites are distributed over streams of various sizes, ranging from first order streams of small, head-water catchments to eighth order rivers with drainage areas exceeding 60,000 km2. Permitted daily withdrawals (PDWs) from the 298 sites examined here range from 55 to 18,314 m3/d and do not vary consistently with natural stream flows. Comparison of PDWs to stream flow statistics (computed from a regression-based approach) indicates that first and second order streams with drainage areas &lt;70 km2 are at risk for withdrawal stress, whereas streams with larger drainage areas (&gt;100 km2) are under little stress from PDWs, even when the cumulative effects of upstream withdrawals are considered. Pass-by flow requirements prescribed on a monthly, rather than annual, basis appear to provide the best year-round protection for low flows, and are consistent with published recommendations for in-stream flow requirements. Our findings also indicate that freshwater consumption – when normalized to gas-well completion activity – has declined since 2011, which implies that sourcing, re-use, and storage of freshwater has evolved considerably since the outset of natural gas development in the Marcellus Shale Play. This work will help to inform decisions on decentralized water withdrawal management schemes, especially withdrawals from small and headwater streams, and help regions with prospective shale gas development better understand water needs and water resource impacts.

Appropriation of fresh water for shale gas development in Pennsylvania's Marcellus Shale

249th National Meeting (2015)

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