Atrazine is an herbicide, or weed killer, that has been used on corn and other crops for many years in Wisconsin. It is registered as a restricted use pesticide in Wisconsin due to potential impacts to groundwater and drinking water from field use, spills, and improper disposal. Atrazine and its metabolites (substances formed as it breaks down in the environment) has been discovered in Wisconsin's groundwater. At low concentrations in drinking water atrazine does not cause immediate sickness or health problems, and the U.S. Environmental Protection Agency classified atrazine as "not likely to be carcinogenic". However, if people drink water for many years that contains low concentrations of atrazine or its metabolites, there is a risk that they may develop cardiovascular, reproductive, or other health problems. In Wisconsin, the sum of atrazine and its metabolites are considered a public health concern at concentrations in excess of of 3 ppb (parts per billion).
This level is known as the enforcement sandard, which means that if found at or greater than the regulatory level, DATCP can take measures to protect groundwater by prohibiting its use. This is done through an administrative rule changes to Wis. Admin. Code § ATCP 30, or through an administrative order. Under ATCP 30, atrazine use is currently prohibited within 101 designated areas known as prohibition areas. Outside of these areas atrazine can be used in accordance with restricted use requirements.
DATCP routinely collects samples from private wells within prohibited areas that exceeded the enforcement standard for atrazine. DATCP also performs audits for agricultural fields within and outside of a prohibition area to ensure compliance with restricted use requirements for atrazine.
Groundwater quality reports
Bureau of Agrichemical Management