Estimation of the Prevalence of Undocumented and Abandoned Rural Private Wells in McDonough County, Illinois


A systematic method of estimating undocumented private wells in the state of Illinois has not been established; this study fills that void. Data from a 1934 well survey of one quarter of McDonough County, Illinois, along with old plat books showing existing structures, were used to compute ratios of wells to structures for the rural portions of the county. Applying these ratios to the portions of the county that were not included in the 1934 well survey produced estimates ranging from 676–1,116 undocumented wells in 1934. Well-to-structure ratios as of 1997 were calculated by using the results of the 1934 estimate and incorporating records of well installation or well sealing from 1935–1997. Some of these anomalously high ratios were explained by the existence of structures that were not represented on the plat maps, but high ratios (>2) in the rural parts of the county were shown to provide evidence for the likely existence of abandoned wells or wells that were sealed without documentation.


Speaker / Author: 
Steve Bennett, PhD, Department of Geology, Western Illinois University
Chad Sperry, MS, GIS Center, Western Illinois University
Month Year: 
December 2018
Page #: 
Publication Month: 
December 2018
EH Topics: