By Scout Nelson
Each year beginning in May, the Minnesota Department of Agriculture (MDA) collects water samples from rivers and streams to assess the presence of pesticide chemicals. These tests are important for understanding water quality and the potential impacts of pesticide use on aquatic life.
In 2024, MDA scientists collected over 1,000 water samples from 56 locations across the state. These samples were analyzed for 185 pesticides and their breakdown products. The findings are shared in the newly released 2024 Water Quality Monitoring Report and will also appear in the MDA’s new interactive StoryMaps tool.
Of the 185 chemicals tested, 81 were detected in at least one sample. Common detections included hydroxyatrazine, metolachlor and its degradates, and 2,4-D. According to the MDA, most pesticide detections were below levels that pose a risk to aquatic life.
However, the concentration of chemicals is as important as their presence. The MDA uses “reference values” set by state and federal agencies to determine whether detected levels are a concern. These values are based on the potential harm pesticides can cause to aquatic life.
In 2024, eight pesticides were found above their reference values. Two insecticides, clothianidin and imidacloprid, made up 90% of these high detections. Other chemicals above reference levels included acetochlor, pyroxasulfone, bifenthrin, tebupirimfos, atrazine, and chlorpyrifos.
“While multiple pesticides are detected in rivers and streams in Minnesota, the majority of detections are below levels of concern for aquatic life.”
The MDA encourages following water quality best management practices (BMPs), available on their website. These practices help reduce pesticide runoff from both agricultural and non-agricultural applications. Stay tuned for Part 2 covering Minnesota’s groundwater monitoring next week.
Photo Credit:istock-dorin-s
Categories: Minnesota, General