Terkhiin Tsagaan Lake (Mongolian: Тэрхийн Цагаан нуур, romanized: Terkhiin Tsagaan nuur, [tʰirˈçin t͡sʰaˈʁaɴ nʊːr], is a fresh-water lake in the Khangai Mountains in central Mongolia, located in Tariat soum of Arkhangai province. In 670 km to the capital city Ulaanbaatar and 180 km to the center of Tariat soum.

The Khorgo volcano is located near the eastern end of the lake, 10 rivers join this lake and only the Suman River springs from it. The lake is located in Khorgo-Terkhiin Tsagaan Nuur National Park. According to the joint 2022 study of Mongolia's Ministry of Environment and Tourism and World Wide Fund for Nature, the area of the lake decreased by 6.4% from 7950.0 ha in 1995 to 7440.1 ha in 2015. This resulted in reduction of wetlands areas by 23.5% and increase by 39.4% of sands and eroded lands surrounding the lake.

An ancient time, a mother and son were living this land and they carried their drink water from small fountain from the deep of ground. After they take some water they have to bung it. But one day son went to this fountain to take drink water but he forgot to bung it after take and he slept next to the fountain. Later some minutes this some area covered by huge water and son's mother worried about his son and she take top of mountain named "Uran mandal", bung the fountain. Since that time this lake is exist here. The top of "Uran mandal" mountain is Small Island that mentioned above.

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• Taryatu-Chulutu
• Тэрхийн цагаан нуур mn:Тэрхийн цагаан нуур
• Олон улсын ач холбогдол бyхий ус, намгархаг газар: Тэрхийн цагаан нуур, 2022 (Wetlands of international importance: Terkhin tsagaan lake, 2022)
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