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¹ Republic of Türkiye Ministry of Agriculture and Forestry, General Directorate of Agricultural Research and Policies Central Fisheries Research Institute, 61500, Yomra, Trabzon, Türkiye.
² Republic of Türkiye Ministry of Agriculture and Forestry, General Directorate of Agricultural Research and Policies Sheep Breeding Research Institute, 10200, Bandırma, Balıkesir, Türkiye. DOI : 10.4194/AQUAST3145 Viewed : 22 - Downloaded : 12 This study provides a seasonal comparative assessment of water quality and trophic status in Almus Dam Lake by evaluating monitoring data from 2019 and 2024. Seasonal vertical profiles and water samples collected from five stations were analysed for temperature, dissolved oxygen, pH, electrical conductivity, nutrients, chlorophyll-a, Secchi depth, trophic indices, and trace elements. The results showed that Almus Dam Lake exhibits a typical monomictic reservoir structure, with winter mixing and clear thermal stratification from late spring to early autumn. Dissolved oxygen conditions were generally suitable for aquatic life, although episodic hypolimnetic oxygen depletion occurred during stratified periods. Most physico-chemical variables and inorganic nitrogen fractions indicated Class I water quality according to the Turkish Surface Water Quality Regulation, while conductivity showed locally moderate conditions. Overall, trophic indicators classified the lake as oligotrophic to low-mesotrophic. However, the 2019–2024 comparison revealed an increase in phosphorus pressure, a shift in nutrient balance, and elevated TP-based trophic signals in deeper waters. This pattern suggests that the reservoir is becoming more phosphorus-sensitive, although relatively low chlorophyll-a levels indicate that persistent whole-lake eutrophication has not yet developed. Trace-element concentrations remained below regulatory thresholds, suggesting limited short-term metal contamination risk. The study provides an updated comparative baseline for Almus Dam Lake and highlights the need for continued monitoring of nutrients, oxygen dynamics, and trace elements to prevent future eutrophication risk. Keywords : Almus Dam Lake, Reservoir limnology, Water quality, Trophic state, Physico-chemical characteristics