The water demand associated with unconventional fossil fuel extraction and the management of the associated produced wastewater present significant environmental challenges. Water usage for unconventional fossil fuel extraction varies in different areas of the country, but overall is a small fraction of total water withdrawals for most locations. Produced water volumes and quality also vary nationwide, and disposal can have significant environmental impacts, especially if produced water is discharged to surface waters. This work discusses water use and requisition, changes in quantity and management of produced water nationwide from 2007 to 2017, and the environmental effects of management options. As unconventional natural gas production expands, selection of management options that do not lead to significant environmental impacts must be prioritized.

Historical data can be used to evaluate water impacts from unconventional oil and gas extraction. “Grey” literature measurements of water quality before, during, and after unconventional extraction activities offer a potentially powerful resource for the evaluation of water quality impacts, and these data have rapidly expanded with regulatory response to the unconventional boom. However, historical data are limited in the variety of measured constituents and require substantial effort to reconstruct, revisit, and re-evaluate. Ultimately, available data were limited as data from only a single county (Bradford) included constituents necessary to use the vast majority of these elemental ratio systems. Further, even when data were available, they were often measured with relatively poor sensitivity, precluding their use as early indicators of contamination. This case study accentuates the continued need to establish background conditions, particularly in regions that have accumulated historical impacts, and further, ensure these characterizations incorporate sensitive testing for known chemistries associated with emerging and novel processes.

Metal isotope tracers (e.g., 87Sr/86Sr, 7Li/6Li; 138Ba/134Ba) are being employed worldwide to understand downhole processes and assess the environmental impact of hydraulic fracturing. These isotope signatures can be much more sensitive than geochemical tracers alone in discriminating between contaminant sources. This can be particularly useful when time has elapsed after an event and a contaminant has been substantially diluted, or in being able to quickly detect the intrusion of a brine with high total dissolved solids (TDS) into a protected water resource. In some cases, such as areas with multiple sources of water contaminants and overlapping chemical signatures, a multi-proxy approach is recommended. The combination of element ratio and isotopic tracers (e.g. Sr/Ca and 87Sr/86Sr) or multi-isotope tracers (e.g., 87Sr/86Sr and d7Li) can be used to discriminate between multiple contaminant sources and provide important information about the processes involved in concentrating, mobilizing or retaining a contaminant.

The chapter explores the water–energy nexus associated with conventional and unconventional (tight) oil exploration, provides water-intensity values associated with conventional oil drilling and enhanced oil recovery, and hydraulic fracturing. The chapter explores the source, volume, geochemistry, and water quality issues of conventional and unconventional oil produced water. The chapter explains the nature and origins of oil field brines, as well as the inorganic (salts, metals, and naturally occurring radioactive elements) and organic constituents. The chapter evaluates the impact of oil produced water on the environment, as well as the ability to reuse oil produced water for beneficial use. The chapter explores the water use and quality associated with oil sand extraction and processing and possible environmental effects as well as oil refining. The chapter evaluates the impact of oil spills on water resources. The chapter examines policy mechanisms that influence the extent of environmental externalities that have emerged from oil production and exploration, including government regulations, forms of corporate society responsibility, and types of contracts.