Lead Concentration Variabilities of Private Water Supplies Located in Door County, Wisconsin

Groundwater contamination exists in Door County because of its many land use practices and a susceptible hydrogeologic environment. This discussion dwells only on the lead contamination of drinking water supplies which appear to be the resultant of lead/arsenate pesticide use and handling practices in orchard areas. Although it is now over twenty years since widespread use of the pesticide, a large number of water supply wells show intermittent susceptibility to contamination by lead, an ingredient of the pesticide.

Groundwater sampling results from private wells indicate there is no assurance that a well does not have lead contamination susceptibility if only one sample has been collected from that well. For this reason, it is best to take more than one sample and to collect those samples when the ground is thawed and one to three days after a peak precipitation or runoff event.

Lead is the only ingredient of the pesticide that has been found in drinking water supplies to date. Arsenic has not been detected.