On 15 January 1965 the Soviet Union detonated a 140 kiloton nuclear device underneath a dry bed of the Chagan River, Kazakhstan. Part of the Soviets´ Nuclear Explosions for the National Economy programme, the raised rim of the resulting crater dammed the river allowing the creation of a reservoir. It is now known as Lake Chagan and has a volume of around 100,000 m³ (3,531,000 ft³).