ABSTRACT

With the advance of hydraulic fracturing technology and improvements in horizontal well drilling, the development of natural gas supplies from deep shale formations has expanded and US natural gas supply estimates have risen dramatically (1). These resources have significant economic value and could generate local air quality benefits if gas displaces coal in electricity generation and for climate change if fugitive methane emissions are sufficiently small (2). Nonetheless, shale gas development has drawn significant public and regulatory attention to potential negative environmental externalities, particularly water quality impacts in the Marcellus Shale region (3, 4).