The Upper Pearl River and its watershed is the main source of water flowing into the Ross Barnett Reservoir, the City of Jackson’s major drinking water supply. Groundwater characterization of the watershed was achieved by analyzing viable groundwater wells and a groundwater spring best representing the land use and land cover extraction map created. Incorporated surface geology demarcated specific stratum, helping describe the different hydrogeochemical interactions observed. Analysis indicated that chloride and nitrate exceeded the Maximum Contamination Levels (MCLs) possibly contributing to eutrophication in the reservoir. Several of the metal and trace elements analyzed were below the MCLs, with the exceptions of manganese, aluminum, and iron. No pharmaceuticals, pesticides, or industrial residues exists in Carthage and Philadelphia’s groundwater, the largest cities in the region. Conclusively, the watershed’s groundwater contains high concentrations of anions along with metal concentrations associated with the ferruginous sandy-clay surface geology moving closer to the reservoir.