Shagan (lake, Abai Region)

Shagan Lake in Kazakhstan (often referred to as Lake Chagan or the “Atomic Lake”) is an artificial crater lake formed in January 1965 by a Soviet underground nuclear test designed to create a reservoir. The explosion excavated a large crater that later filled with water, producing an unusual human-made lake within the former Semipalatinsk testing region.

The site is notable for its association with the Soviet ‘peaceful nuclear explosions’ program and remains an object of interest for visitors and researchers examining the legacy of nuclear testing. Measurements and monitoring have been carried out periodically by authorities and researchers since the test.

The crater was created during Project Chagan in 1965 as an experiment to explore non-military uses of nuclear explosions; the resulting basin filled from local watercourses to form the lake. Over time the lake and surrounding area have been subject to studies of radiological and ecological conditions.

The lake sits in eastern Kazakhstan’s Abai Region within the territories formerly used for the Semipalatinsk nuclear test site; access is controlled and the area is remote from major population centres.

• Origin and nickname: Often called "Atomic Lake", it was formed by a Soviet nuclear experiment in 1965 and lies within the broader Semipalatinsk test area under restricted oversight.