Evaluating the effectiveness of a fixed wellhead delineation: regional case study

• Published in: Journal of the American Water Resources Association 2006-04, Vol.42 (2), p.409-423
• Main Authors: Hodgson, J.Y.S, Stoll, J.R, Stoll, R.C
• Format: Article
• Language: English
• Subjects: case studies; dolomite aquifer; drinking water; Earth sciences; Earth, ocean, space; Exact sciences and technology; ground water management; groundwater contamination; Hydrogeology; Hydrology. Hydrogeology; karst; karsts; laws and regulations; prediction; Source Water Assessment Program; source water protection; statistical models; surveys; water policy; water pollution; Water resources; wellhead protection; wellhead protection area delineation; wells
• ISSN: 1093-474X; 1752-1688
• DOI: 10.1111/j.1752-1688.2006.tb03847.x

The 1996 Safe Drinking Water Act amendments mandated that every state must determine the hydrogeologic origin of each public drinking water system and assess the degree to which each system may be adversely affected by potential sources of contamination. Wisconsin delineated and assessed one specific class of systems, transient noncommunity drinking water wells, with the least stringent standards of all governed system types. This study evaluates the effectiveness of Wisconsin's arbitrarily fixed radius approach used in determining susceptibility to potential contamination from 1,872 transient noncommunity ground water wells. Nearly 28 percent of the wells with contaminated water did not have any recorded potential sources of contamination within the delineation radii. Additionally, regression models derived from potential contaminant inventories within the delineation radii could not accurately predict actual incidences of water contamination. Differences between observed and expected frequencies of contamination further suggest that some transient noncommunity systems should probably be delineated with larger and more sophisticated methods that would account for varying geology and contaminant susceptibility. The majority of contamination cases without recorded potential sources of contamination within the delineation radii were in a karst area. Subsequently, the arbitrarily fixed radius delineation method should not be used in areas with karst aquifers.