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Locations with High Reliance on Private Wells: Not Always Where You Think They Are
Citation:
Weaver, James W., A. Murray, AND F. Kremer. Locations with High Reliance on Private Wells: Not Always Where You Think They Are. Private Well Conference, Champaign, Illinois, May 23 - 25, 2017.
Impact/Purpose:
Presenting at the Private Well Conference
Description:
For developing contaminant management strategies and protecting drinking water supplies, the locations of areas with reliance on private domestic wells (PDWs) and their relationship to contaminant sources need to be determined. From 1960 to 1990, a key resource in determining areas of reliance on PDWs is the U.S. Census where the source of domestic drinking water was a survey question. To provide an updated estimate of PDW use, two methods were developed to estimate the areal density of PDW use in using readily accessible data including the 1990 census results. Because of their abundant data on PDW locations, public water supplies, and underground storage tank locations, Oklahoma was used for a pilot project to determine the well density and underground storage tank relationships. Well logs reported to the Oklahoma Water Resources Board and the addition of housing units provided the means to update the 1990 census estimates. Census results and housing unit data are available on the county, census tract, and census block group level. PDW density estimates were consistent among these scales, as were estimates based on reported well logs and net housing units. The completeness of reported well logs was tested by counts from neighborhoods with known reliance on PDWs. The results showed a significant underreporting of well logs. The small scale of subdivisions relative to even census block groups caused the method estimates to be lower than subdivision PDW densities. The estimates, however, indicate locations where high densities of PDWs may be expected. The relationship between underground storage tank sites (USTs) and PDWs was determined by selecting distances of interest (up to 1 mile) and searching all census block groups for reported wells, adding randomly-placed wells to match the estimated spatial density, and determining the distances between known UST and the reported and randomly-placed wells. The procedure was repeated 10,000 times which determined that there were 27% of USTs had at least one PDW within (300 m) 1,000 ft and 66% had at least one PDW within 1,609 m (5,280 ft).