Report on the Bacteriological Water Quality Monitoring of Door County Variance and Special Casing Approval Wells

Purpose: Between September 1971 and January 1990, approximately 1,500 variances and approvals, to install less than the required amount of protective well casing, were granted by the Department of Natural Resources for wells constructed in Door County, Wisconsin. This creates some concern about the safety of the wells. How effective are those wells in preventing bacteriological contamination from entering the water supply?

The main purpose of this project was to determine if the granting of variances and approvals resulted in the construction of wells producing bacteriologically unsafe water. This was accomplished by collecting water samples from 192 wells and submitting those samples to the State Laboratory of Hygiene in Madison for bacteriological analysis. In addition, samples were collected for analysis of nitrates, sulfates and iron to help characterize the aesthetic quality of the groundwater. Twelve of the 192 wells were selected for analysis of radium in the water. Radium is a radioactive element suspected of causing bone cancer. Half of the wells in the radium portion of the study obtained water from the deep aquifer (total well depths range from 580 to 735 feet) while the other half obtained water from the shallower aquifer (total well depths range from 90 to 201 feet).