Groundwater Monitoring Project for Pesticides

The objective of this study is to determine the extent of groundwater contamination resulting from pesticide use in highly and moderately susceptible areas of the state.  In this study highly susceptible areas are defined as having sandy soils, less than 25 ft. to groundwater, and irrigation.  Areas of moderate susceptibility are defined as having loamy soils and 15 to 50 ft. to groundwater with or without irrigation.  The pesticides of interest atrazine, alachlor, aldicarb, metolachlor, metribuzin, carbofuran, and several other compounds that have chemical characteristics and use patterns which make them relatively susceptible to leaching.

Part of the motivation for this study, which utilizes monitoring wells, was the belief that the investigation of pesticides in groundwater should be expanded beyond the limited zones of groundwater accessible by drinking water wells.  This is consistent with the Wisconsin Groundwater Law, which directs agencies to look at all points of standards applications when assessing groundwater contamination.

The monitoring results from this study are compared to any standards that have been established in s. NR 140, Wis. Admin. Code.  A determination can then be made whether regulatory actions are needed to prevent these pesticides from entering groundwater above an official groundwater standard.  Under ch. 160, Stats., the Department of Agriculture, Trade, and Consumer Protection (DATCP) must adopt preventive rules, within its jurisdiction, to limit the presence of pesticide substances in groundwater.  In order to fulfill this directive, DATCP must know the nature and extent of the problem to be addressed.