An Evaluation of Water Quality in Private Drinking Water Wells Near Natural Gas Extraction Sites in the Barnett Shale Formation

• Published in: Environmental science & technology 2013-09, Vol.47 (17), p.10032-10040
• Main Authors: Fontenot, Brian E, Hunt, Laura R, Hildenbrand, Zacariah L, Carlton Jr, Doug D, Oka, Hyppolite, Walton, Jayme L, Hopkins, Dan, Osorio, Alexandra, Bjorndal, Bryan, Hu, Qinhong H, Schug, Kevin A
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Applied sciences; Aquifers; Arsenic; Chromatography, Gas; Crude oil, natural gas and petroleum products; Drinking water; Drinking Water - analysis; Earth sciences; Earth, ocean, space; Energy; Engineering and environment geology. Geothermics; Exact sciences and technology; Extraction and Processing Industry; Fuels; Groundwaters; Mass Spectrometry; Natural gas; Natural gas reserves; Natural water pollution; Oil and Gas Fields; Oil wells; Pollution; Pollution caused by production, transportation and treatment of oil and oil shales. Water and soil pollution. Treatments. Pollution control; Pollution, environment geology; Selenium; Texas; Water Pollutants, Chemical - analysis; Water Quality; Water treatment and pollution; Water Wells - analysis
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es4011724

Natural gas has become a leading source of alternative energy with the advent of techniques to economically extract gas reserves from deep shale formations. Here, we present an assessment of private well water quality in aquifers overlying the Barnett Shale formation of North Texas. We evaluated samples from 100 private drinking water wells using analytical chemistry techniques. Analyses revealed that arsenic, selenium, strontium and total dissolved solids (TDS) exceeded the Environmental Protection Agency’s Drinking Water Maximum Contaminant Limit (MCL) in some samples from private water wells located within 3 km of active natural gas wells. Lower levels of arsenic, selenium, strontium, and barium were detected at reference sites outside the Barnett Shale region as well as sites within the Barnett Shale region located more than 3 km from active natural gas wells. Methanol and ethanol were also detected in 29% of samples. Samples exceeding MCL levels were randomly distributed within areas of active natural gas extraction, and the spatial patterns in our data suggest that elevated constituent levels could be due to a variety of factors including mobilization of natural constituents, hydrogeochemical changes from lowering of the water table, or industrial accidents such as faulty gas well casings.