This study assesses uranium (U) and molybdenum (Mo) contamination in groundwater and surface water within the Rietkuil River catchment (similar to 114 km(2)) and the Leeugamka Dam near Beaufort West, South Africa, and evaluates potential health risks to local communities. Twenty water samples were collected from the mine pit, groundwater, and surface water during wet (September 2018) and dry (July 2019) seasons. Hydrochemical analysis, geochemical modelling, spatial assessment, and health risk evaluation were applied to assess the occurrence, mobility, and impacts of these elements. Elevated concentrations of U (up to 6760 mu g/L) and Mo (up to 266 mu g/L) in mine pit water indicate active leaching likely driven by rainfall infiltration. Groundwater concentrations decreased downstream over similar to 10 km, suggesting dilution and dispersion. Although surface water samples complied with World Health Organization (WHO) and South African National Standards (SANS) guidelines, two groundwater samples exceeded the Health Canada limit for U (20 mu g/L). Speciation modelling indicated that uranyl hydroxide complexes were dominant, thereby enhancing uranium mobility. The health risk assessment showed that nitrate (NO3-) in groundwater posed the greatest non-carcinogenic risk, with Hazard Quotient (HQ) and cumulative Hazard Index (HI) exceeding acceptable limits, particularly for children during the dry season. This study advances understanding of uranium and molybdenum behaviour by integrating their sources, hydrogeochemical controls, and seasonal variability with spatial patterns of contamination and associated health risks in a semi-arid, mining-impacted environment. The findings underscore the need for targeted groundwater monitoring near legacy mining features and for incorporating seasonal variability into groundwater management strategies.