Madatapa is a lake in the southeastern part of the Javakheti volcanic highlands, in Ninotsminda municipality, 2,108 m above sea level. Surface area 8.78 km², basin area 136 km², greatest depth 1.7 m, volume 9.7 million m³. The basin was formed when a lava flow blocked the valley. It is fed by snow, rain and groundwater. Its level is high in spring and low in winter. The Madatapa River flows out of the lake; it also has underground drainage, which makes its level fluctuate sharply. The water temperature in summer is 17–18°C; in winter it freezes almost to the bottom. The water is slightly mineralized. The lake has little economic importance and holds no fish; in summer waterfowl abound. From the lake rises the Bughdasheni River, which joins the Paravani at the entrance to Ninotsminda. Around the lake lie the villages of Efremovka, Zhdanovakani and Sameba.