The state estimates one or more pesticides are found in around 43 percent of 800,000 private wells in Wisconsin, and more than half of the pesticides detected aren't regulated in groundwater by the state or federal governments.
The findings stem from an analysis of 380 wells sampled last year as part of a statewide survey to assess pesticides and nitrates in groundwater. It's conducted every five to 10 years by the Department of Agriculture, Trade and Consumer Protection, or DATCP. The estimate of wells with pesticides is up slightly from 41.7 percent since the last survey in 2016.
Results released this year show detections of 29 individual pesticides out of 107 compounds tested that include chemicals known as neonicotinoids, which are insecticides known to be toxic to bees and birds.
The findings revealed only one well-exceeded health advisory level recommended by the state Department of Health Services, or DHS, for any of the compounds tested. Even so, Carla Romano, a groundwater specialist with DATCP, said state officials couldn't assess health concerns for some of the pesticides.
Read more at Wisconsin Public Radio.