The City of Waupaca, Wisconsin, uses groundwater pumped from a network of seven high-capacity wells as its municipal water supply. Recent increases in the concentration of nitrate in the municipal water supply raised questions about the source of this contamination and whether it might eventually exceed standards for drinking water. This study combines geologic, hydrologic, land-cover, water-use, and water-quality data from the area with a groundwater-flow model to simulate and predict the effects of different land and water use on the concentration of nitrate in groundwater pumped from two of the city’s municipal wells. The resulting tool supports decision makers who are tasked with land-use management and demonstrates a study design that could be applied to well-head-protection efforts elsewhere in Wisconsin’s Central Sands region. Suggested Citation: DeVries, S.L., Bradbury, K.R., Cardiff, M., 2022, A groundwater-flow model and effective nitrate calculator for Waupaca, Wisconsin: Wisconsin Geological and Natural History Survey Technical Report 007, 88 p., https://doi.org/10.54915/xdis1726 .