Lake Karachay

Lake Karachay (Russian: Карача́й), sometimes spelled Karachai or Karachaj, was a small lake in the southern Ural Mountains in central Russia. Starting in 1951, the Soviet Union used Karachay as a dumping site for radioactive waste from Mayak, the nearby nuclear waste storage and reprocessing facility, located near the town of Ozyorsk (then called Chelyabinsk-40). Today the lake is completely infilled, acting as "a near-surface permanent and dry nuclear waste storage facility."

The radioactivity of the lake is comparable to the Chernobyl disaster, the worst nuclear accident of all time.