Groundwater maintains springs, surface water, and terrestrial ecosystems which support habitats of aquatic and terrestrial species of conservation interest. These species depend on groundwater availability and consistent water quality (salinity and temperature), which may be threatened by droughts and exacerbated by unsustainable groundwater withdrawals and contamination related to human activities. For example, advances in directional well drilling and hydraulic fracturing rapidly increased oil and gas production from unconventional oil and gas plays since mid‑2000s. In west Texas, the arid Permian Basin (rain≈30 cm/yr) has the greatest potential for energy development (~1,000s unconventional wells), but also includes the Pecos River watershed, numerous spring systems, and habitats for many federally protected species. Groundwater and surface water are strongly interconnected, with springs issuing from aquifers used as water sources. Oil and gas well completion requires ~6 million gallons per well, which could stress aquifers and reduce flows to streams and springs. Furthermore, produced saline waters (a volume≈3 times greater than oil production; Scanlon et al. 2017) must be properly managed to mitigate vulnerability. Thus, the water-energy-ecosystem nexus is inextricably linked to groundwater‑dependent habitats. Collaborative industry-academia approaches are needed to develop science needed to mitigate potential ecosystem impacts from unconventional oil and gas development.
Results/Conclusions
We present our approach to improve vulnerability assessments and systems monitoring to mitigate habitat degradation from Permian Basin unconventional energy development. We recognize vulnerability includes dewatering and contamination of groundwater dependent ecosystems. This approach includes (1) developing a conceptual model of the groundwater flow system and conducting a preliminary vulnerability assessment, (2) identifying gaps in understanding, collecting new data through environmental monitoring, and (3) updating the conceptual model and vulnerability assessment. Our initial hydrogeological model includes regional groundwater with long residence (1,000s years) and storm water with shorter, faster flows paths to springs (days‒weeks), allowing us to preliminarily delineate a portion of the Permian Basin with greater vulnerability where potential fast-flow groundwater conduits are excluded from industrial operations. Our largest gap relates to local recharge processes and spring response. We are currently improving our understanding of the rainfall-runoff process by measuring mountain-front precipitation, ephemeral stream discharge, and monitoring groundwater and spring response. An improved understanding of groundwater sources, vulnerability to dewatering and contamination, and connectivity to habitats—developed in collaboration with operators—is essential to assessing and mitigating potential vulnerabilities of groundwater-dependent ecosystems. While applied to the Permian Basin, this approach is applicable to unconventional plays with groundwater-dependent ecosystems globally.