ABSTRACT: In this study, geological and hydrogeological properties of Karagöl and its surroundings were investigated and hydrogeochemical properties and quality of waters were evaluated. The rock units are observed with different age and lithology in the Upper Cretaceous-Quaternary time interval in the study area. The groundwater reservoirs are alluvium and fractured-fissured magmatic rock units with locally limestone, sandstone levels. The most important surface waters are Çoruh River and Karagöl Lake in the region. In order to determine hydrogeochemical properties of the surface and spring waters, hydrochemical analyses were performed. According to the obtained results, the water resources are in Ca-HCO3, Ca-Mg-HCO3, and NaHCO3 facieses. The main factor in the development of water types is water-rock interactions. In general, increase of Na and Ca ions is related to Na-Ca feldspars alteration, while the Mg ions are mainly due to the weathering of silicate minerals such as biotite, amphibole, pyroxene. On the other hand, dominant HCO3 ion shows an increase associated with limestone and clayey limestone units, and also with the secondary calcite minerals which are formed as a result of the feldspar mineral alteration. Water resourcesare classified as 1st water quality in terms of all parameters and suitable for drinking and irrigation.