Mamay () is a salt lake in the Akmola Region, Kazakhstan.
The lake straddles the Birzhan sal District in the west and the Akkol District in the east. Mamay village is located by the northern lakeshore. The area surrounding lake Mamay is used for agricultural fields and livestock grazing.
Mamay is an endorheic lake of the northern end of the Kazakh Uplands. It lies in a basin among low hills at an elevation of . The Tattimbet river flows into the lake from the southwest.
The lakeshore is gently sloping and sandy except for a steep stretch near the Tattimbet river mouth. The bottom is flat and covered with an approximately thick layer of silt. The water is green and has a bitter taste. Mamay is replenished by rain and snow. Among the lakes in its vicinity, Itemgen lies to the south, Shoshkaly to the southwest, Atansor to the northeast and Kotyrkol to the northwest.