The aim of this study is to evaluate the water quality of Germeçtepe dam lake located in the Daday district of Kastamonu province and to determine the temperature, pH, turbidity, conductivity, dissolved oxygen, nitrate, nitrite, phosphate, ammonia, COD and BOD in terms of 11 physico-chemical parameters. The temperature, pH, conductivity and dissolved oxygen parameters of the water samples were analyzed study land using multimeter and other parameters were determined using sproctrophotometric method in the laboratory. The physicochemical parameters determined in the lake water were between 1.07-24.5 ° C, pH 7.32-9.98, turbidity 0.74-8.17 NTU, dissolved oxygen 7.23-11.35 mg -1, conductivity 332-459 μS cm-1, nitrite 0.0-0.008 mg -1, nitrate 0.0-0.87 mg -1, phosphate 0.04-3.53 mg-1, ammonium 0.0-0.53 mg -1, COD 8.41-23.13 mg-1 and BOD Has been found to vary between 0.0 and 2.0 mg-1. All of the a data set (12 months) about several physico-chemical parameters such as temperature, pH, conductivity, dissolved oxygen, nitrate, nitrite, phosphate, Ammonia, COD and BOD was collected from 3 monitoring stations in Germeçtepe Dam Lake were evaluated with statistical analysis. In the results of the analysis, Germeçtepe dam reservoir water quality was determined as the first quality in terms of temperature, pH, dissolved oxygen, conduction, nitrate, ammonium, COD and BOD parameters in terms of nitrite. In terms of quality and phosphate, IV. It has been determined that quality is in the water class and it is determined that the lake water is not in an important pollution pressure.