A detailed risk assessment of shale gas development on headwater streams in the Pennsylvania portion of the Upper Susquehanna River Basin, U.S.A

• Published in: The Science of the total environment Vol. 610-611; pp. 154 - 166
• Main Authors: Maloney, Kelly O., Young, John A., Faulkner, Stephen P., Hailegiorgis, Atesmachew, Slonecker, E. Terrence, Milheim, Lesley E.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.01.2018
• Subjects: Brook trout; Development intensity; Hydraulic fracturing; Risk; Unconventional oil and gas; Vulnerability; Unconventional oil and gas; Risk; Vulnerability; Brook trout; Hydraulic fracturing; Development intensity
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2017.07.247

•Infrastructure, water withdrawals, and spills from UOG cumulatively affect ecosystems.•A disturbance intensity index was developed that captured all these potential effects.•Well density correlated with well pads and production metrics but not other measures.•Some catchments and high quality streams were in medium-high disturbed areas.•A large proportion of catchments and streams were at high risk to future development. [Display omitted] The development of unconventional oil and gas (UOG) involves infrastructure development (well pads, roads and pipelines), well drilling and stimulation (hydraulic fracturing), and production; all of which have the potential to affect stream ecosystems. Here, we developed a fine-scaled (1:24,000) catchment-level disturbance intensity index (DII) that included 17 measures of UOG capturing all steps in the development process (infrastructure, water withdrawals, probabilistic spills) that could affect headwater streams (<200km2 in upstream catchment) in the Upper Susquehanna River Basin in Pennsylvania, U.S.A. The DII ranged from 0 (no UOG disturbance) to 100 (the catchment with the highest UOG disturbance in the study area) and it was most sensitive to removal of pipeline cover, road cover and well pad cover metrics. We related this DII to three measures of high quality streams: Pennsylvania State Exceptional Value (EV) streams, Class A brook trout streams and Eastern Brook Trout Joint Venture brook trout patches. Overall only 3.8% of all catchments and 2.7% of EV stream length, 1.9% of Class A streams and 1.2% of patches were classified as having medium to high level DII scores (>50). Well density, often used as a proxy for development, only correlated strongly with well pad coverage and produced materials, and therefore may miss potential effects associated with roads and pipelines, water withdrawals and spills. When analyzed with a future development scenario, 91.1% of EV stream length, 68.7% of Class A streams and 80.0% of patches were in catchments with a moderate to high probability of development. Our method incorporated the cumulative effects of UOG on streams and can be used to identify catchments and reaches at risk to existing stressors or future development.