Physicochemical characteristics and planktonic diversity and key criterion for determining the quality of water. Kaylana Lake has the greatest importance for residents of Jodhpur. The specific physicochemical characteristics and diversity of plankton in Kaylana Lake has been studied through seasonal surveys in two annual cycles (2019-20 and 2020-21). The water remained moderately alkaline (pH) while electrical conductance (0.3458 mS/cm), chloride (168 mg/l), TDS (242 mg/l), hardness (178.36 mg/l), and alkalinity (211 mg/l) showed low mean value. Average dissolved oxygen levels were at 5.89 mg/l while average phosphate and nitrate levels were 2.88 mg/l and 3.82 mg/l respectively. The physicochemical characteristics of the Kaylana Lake indicate that water was polluted and favourable conditions for eutrophication.