Managing Surface Water Withdrawals for Shale Gas Development: Evaluation of Regulatory Standards

Hydraulic fracturing in Pennsylvania’s Marcellus Shale used approximately 45 million cubic meters (12 billion gallons) of water in 2011.  Around 90% of this water was taken from surface water sources.  To manage this new and increasing demand for fresh water, new regulatory approaches and rules for surface water withdrawals are being implemented by state and interstate water authorities in the region. This study is focused on the Ohio River Basin in western Pennsylvania, where operators taking water for shale gas development must comply with statistically-derived withdrawal limits imposed by the Pennsylvania Department of the Environment. These limits were intended to minimize impacts to aquatic ecosystems and other designated or existing uses of water resources. By necessity they are calculated from limited historical stream flow data and are therefore subject to considerable uncertainty.  We use statistical methods to estimate the magnitude of error associated with the calculation of withdrawal limits from daily discharge data and discuss other sources of error and uncertainty not considered by the current regulation. New proposed regulatory approaches, with limits that vary by month, are similarly evaluated. We explore strategies for managing water withdrawals for shale gas development are examined and options that are less sensitive to data limitations.