Shagan (lake)

Shagan (Шаған) or Chagan (Чаган) is a lake in Zhanasemey District, Abai Region, Kazakhstan. Formed by a nuclear test explosion in 1965, it is part of the Balapan complex, one of the main tourist attractions of the Semipalatinsk Test Site.

Geography
The lake lies 90 km to the south of the Irtysh and about 110 km to the southwest of Semey, formerly Semipalatinsk. The lake lies to the north of the confluence of the Shagan river, of the Irtysh basin, and its tributary the north-flowing Ashchysu. The Shagan river was channeled to fill the newly created crater until 1965. A few years later, a dam was built on the left bank of the river to control the water level in the reservoir that formed to the south. The reservoir still exists today, unchanged since the explosion. It is used to provide water for local cattle.

History
The lake was formed in the area known as the Balapan Complex by the Chagan nuclear test on January 15, 1965, which was conducted as part of the Soviet Union Nuclear Explosions for the National Economy program. A 140 kiloton device was placed in a 178 m hole in the dry bed at the confluence of the Shagan and Ashchysu rivers. The blast created a circular crater 400 m across and 100 m deep with a lip height of 20 to 38 m. The crater was filled shortly after the nuclear blast by the water of the rivers and it is often referred to as "Atomic Lake" (Атом көлі). The crater lake's volume is approximately 10 e6m3. To the south, the rim of the crater holds back the waters of a two-lobed reservoir.

It was estimated that some 20% of the radioactive products from the Chagan test escaped the blast zone, and were detected over Japan. This infuriated the United States for violating the provisions of the October 1963 Limited Test Ban Treaty, which banned atmospheric tests.

The water continues to be radioactive – about 100 times more than the permitted level of radionuclides in the water. Locals fish in the lake, despite warnings by authorities that it is hazardous.

Media
In Netflix's documentary series Dark Tourist (season 1 episode 4, "The Stans"), David Farrier visits and swims in Lake Chagan, and eats a fish from the lake, during his tour of Kazakhstan.