Investigation of hydrogeochemical and quality characteristics of Işıklı Lake (Çivril, Denizli)

In this study, the hydrogeochemical characteristics and water quality of Lake Işıklı, one of Turkey's important freshwater resources located within the borders of Denizli province, were evaluated. Within the scope of study, the geological, hydrological, and hydrogeological features of the lake and its surroundings were examined in detail. The hydrogeochemical composition, usage potential, and pollution status of the lake water were determined. Water samples collected from 11 representative points around the lake revealed that the dominant ions are Ca, Mg, and HCO₃. Evaluations based on Piper and Schoeller diagrams indicated that the lake water is of the Ca-Mg-HCO₃ type. Additionally, results from the Gibbs diagram showed that the water composition is largely influenced by rock-water interactions. According to the analysis results, the pH values in some samples exceeded the drinking water standards, and arsenic concentrations surpassed acceptable limits at certain points. However, other heavy metal parameters were generally within permissible ranges. In terms of irrigation water quality, the lake water was classified as very good due to its low sodium content. Statistical evaluations through Pearson correlation analysis revealed strong relationships between certain physicochemical parameters, heavy metals, and water quality indices. The findings suggest that Lake Işıklı can be used for drinking and irrigation purposes under limited conditions, though local geology and human activities significantly affect its water quality.