The impact on natural waters is particularly critical when using the underground well leaching method, therefore mitigating the negative effects on natural waters to an acceptable level during uranium extraction using this method is the cornerstone of this production activity. The aim of the work: to determine the mechanisms of formation of the chemical composition of groundwater in the alluvial aquifer in the area of influence of the Safonivske uranium deposit, which is promising for uranium extraction using the underground well leaching method. In the waters of the study area, albite, halite, anhydrite, gypsum, anorthite, chlorite, and talc are dissolved, and aragonite, calcite, Ca‑montmorillonite, and illite are precipitated. The concentration of Ca2+ is determined by the dissolution of carbonate minerals and the precipitation of Ca-montmorillonite. The concentration of magnesium is determined by a combination of chlorite and talc dissolution processes and illite precipitation. Quartz and Ca-montmorillonite precipitation is possible across the entire pH range, while chlorite precipitation occurs at pH values > 7.6 - 7.8 units. The processes of carbonate mineral and hematite precipitation occur in all waters, with the exception of two wells located in the town of Bashtanka, whose water is characterized by more acidic pH values compared to others. Goethite precipitation occurs in the waters of all wells at all pH values.
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