Shagan Шаған
Irtysh basin with the Shagan in the lower right
Mouth location in Kazakhstan
Physical characteristics
Source	Kazakh Uplands
• location	Chingiztau
• coordinates	48°39′51″N 78°29′03″E / 48.66417°N 78.48417°E / 48.66417; 78.48417
• elevation	915 metres (3,002 ft)
Mouth	Irtysh
• coordinates	50°37′55″N 79°15′45″E / 50.63194°N 79.26250°E / 50.63194; 79.26250
Length	275 km (171 mi)
Basin size	25,400 km2 (9,800 sq mi)
Discharge
• average	1.02 m3/s (36 cu ft/s)
Basin features
Progression	Irtysh→ Ob→ Kara Sea

The Shagan (Kazakh: Шаған - Şağan) is a river in the east of Kazakhstan and a tributary of the Irtysh. The river is 275 km (171 mi) long and the area of its basin is 25,400 km² (9,800 sq mi).

Geography

The Shagan has its sources in the northwestern slopes of the Chingiztau, a subrange of the Kazakh Uplands. It heads mainly northwards along semi-desert areas all along its course. Finally it meets the left bank of the Irtysh 275 km (171 mi) to the west of Semey, former Semipalatinsk, city. Its food is mainly snow and the river is under ice between November and April. It flows during the spring floods, from May to June. In the summer it dries up or breaks up into disconnected pools. Its main tributary is the Ashchysu from the right,^[1][2]

History

It is located in the area of the Semipalatinsk Test Site, which was used as the primary testing venue for the Soviet Union's nuclear weapons. The river flows along the eastern boundary of the test site and fills the "Atomic Lake" Lake Shagan (or Lake Balapan), a lake created by the Chagan nuclear test.^[3] The lake was formed at the confluence with the Ashchysu in January 1965.^[4]