Korgalzhyn is a lake that lies at the bottom of the large Tengiz-Korgalzhyn Depression, close to the southeast of larger Lake Tengiz. Lake Sholakshalkar lies to the east. The lake is shallow, with a maximum depth of 2 meters (6 ft 7 in). Most of it is covered by reeds, except for a few lobes in the northwest and northeast, Kokai, Sultankeldy and Isey, where the surface is relatively free of vegetation. The northern and eastern shorelines are steep and rocky, reaching heights between 4 meters (13 ft) and 6 meters (20 ft), while the western and southern shores are gently sloping and overgrown with aquatic vegetation. The lake bottom is flat and clayey, covered with dark grey silt.[7]
The Nura river flows into the eastern lakeshore from the northeast. During spring floods the overflow discharges into lake Tengiz from the northwestern end. River Kulanotpes flows along the western edge of Korgalzhyn. The water of the lake is fresh near the mouth of the Nura, becoming increasingly brackish towards the northern sector.[2][11]
There are large reed beds scattered on mud islands almost completely covering the southern part with a mesh of open channels and ponds in between. Owing to these mud islands Korgalzhyn is an important wetland site for migratory water birds, such as different species of gulls, terns, ducks and grebes, including the northernmost colony of greater flamingo. The reed thickets also provide a habitat for the wild boar.[8]
