Regulatory authorities in Europe are beginning to rely on federal, state, or regional groundwater monitoring databases as a resource to evaluate the leaching potential of crop protection products. Since groundwater monitoring data may originate from a broad range of sources with varying purpose and design, sporadic detections of a product found in public databases may not be indicative of leaching potential. We present key findings from a case study of an evaluation of available groundwater monitoring data in Europe for a widely-used herbicide. An extensive groundwater monitoring dataset of more than 100,000 analytical results for the product of interest from more than 18,000 wells was compiled. A geospatial GIS-based leaching vulnerability assessment was conducted in order to assess the representativeness of the available monitoring data to characterize leaching potential under existing environmental conditions. The vulnerability assessment identified regions that would favor leaching of the product based on environmental factors and crop footprint representative of potential product use. Groundwater monitoring locations and results were compared spatially with respect to high, medium, or low vulnerability. Site visits to select monitoring wells in the field, along with interviews with local farmers provided valuable insight into the representativeness of the monitoring data. The desktop and field elucidation demonstrated that despite extensive monitoring data, the product was detected infrequently in groundwater, including regions where environmental factors would appear to favor leaching. The case study also demonstrates the importance to evaluate sporadic detections and data outliers when attempting to characterize the representativeness of monitoring data to estimate leaching potential of crop protection products.

Case-study to evaluate the representativeness of public groundwater monitoring data to assess the potential for leaching to groundwater

254th National Meeting (2017)

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