<p>Limnological studies of Derbendikhan Lake were carried out was carried out seasonally over period of 4 season (summer, autumn, winter and spring). The present study deals with physico - chemical parameters and algal composition. The maximum and minimum range of physico - chemical properties were as, 13-34 &deg;C and 12-30 &deg;C for air and water temperature, Electrical conductivity and total dissolved solids varied from 435-485&micro;s/cm and 278-310mg/L respectively, pH on alkaline side of neutrality, alkalinity 200 - 240 mgCaCO3 / L in February and May respectively, harness ranged between 210-280mgCaCO3 /L, the highest value of calcium and magnesium reached to 70mg/L and 34mg/L respectively, minimum value of sodium was 7.0 mg /L and maximum value of potassium was 1.4 mg /L, sulfate value ranged from 125-175mg/L, minimum value of chloride was 24mg/L.Higer value of nitrite, phosphate and silicate was 0.86&micro;gN-NO2 /L, 25&micro;gP-PO4 /L and 0.5&micro;gSi-SiO2 /L respectively.<br /> <br /> A total of 30 species were recorded. Fourteen species of the total belong to Bacillariophyceae, 8 species belong to Chlorophyceae, 5 species to Cyanophyceae, 2 species to Pyrophyta, and 1 species to Euglenophyceae. K</p>