Of the approximately 6.6 million people living in the Mississippi embayment (MISE) region in the central United States, approximately 65 percent rely on groundwater for their drinking water (Dieter, Linsey, and others, 2017). Regional assessments of water quality in principal aquifer systems provide context for the long-term availability of these water resources for drinking-water supplies. To assess the current (2018) status of water quality in MISE in relation to drinking water supplies, groundwater withdrawal zones used for domestic and public supply were modeled using available groundwater well and hydrogeologic framework data. Three dimensional surfaces were modeled to map the depth zones at which groundwater...