By Scout Nelson
Groundwater monitoring plays a key role in protecting Minnesota's agricultural landscape. The Minnesota Department of Agriculture (MDA) conducts annual testing of surface and groundwater across the state to assess the presence of pesticides and their breakdown products. This helps maintain a productive agricultural economy while minimizing risks to human health and the environment.
In 2024, MDA monitored 168 groundwater sites, collecting 225 samples in total. Among 185 pesticide-related chemicals, 55 were detected in the samples. The most frequently detected pesticides included clothianidin, bentazon, fomesafen, sulfentrazone, and thiamethoxam. Breakdown products, such as metolachlor ESA, metolachlor OXA, and acetochlor ESA, also showed high detection rates.
Several pesticides were detected for the first time in 2024, such as clethodim sulfone, clethodim sulfoxide, flutriafol, and halosulfuron-methyl. These compounds are associated with various commercial products used in farming. The breakdown product pyroxasulfone M3 was another first-time detection in groundwater samples.
One of the key findings in the 2024 monitoring was the detection of chlorothalonil's breakdown product, 4-hydroxychlorothalonil. This compound exceeded its reference value in nine groundwater samples, reaching concentrations higher than the drinking water Risk Assessment Advice level of 2,000 ng/L. These detections were found in areas with coarse, sandy soils in Central Minnesota.
Despite some detections, most pesticide levels remained below the established reference values, which are developed by the Minnesota Department of Health (MDH) to safeguard human health. Monitoring efforts will continue to identify trends and take action where necessary, ensuring the health of Minnesota's water sources and the sustainability of its agricultural practices.
Photo Credit:pexels-adam-sondel
Categories: Minnesota, General