Dayan Lake
Dayan Lake
Location	Bayan-Ölgii Province, Mongolia
Coordinates	48°21′32″N 88°49′55″E / 48.35889°N 88.83194°E / 48.35889; 88.83194
Basin countries	Mongolia
Max. length	18 km (11 mi)
Max. width	9 km (5.6 mi)
Surface area	67 km2 (26 sq mi)
Average depth	2.3 m (7 ft 7 in)
Max. depth	4 m (13 ft)
Water volume	0.157 km3 (127,000 acre⋅ft)
Surface elevation	2,232 m (7,323 ft)

Dayan Lake (Mongolian: Даян нуур, Chinese: 达彥湖) is a lake located the district of Sagsai, in the Bayan-Ölgii Province of western Mongolia. It is recognized by BirdLife International as an Important Bird Area since 2009. It is located in the Altai Tavan Bogd National Park.

Dayan Lake remains frozen from October to June. In the area, there are wolves (Canis lupus), red foxes (Vulpes vulpes) and Pallas's cat (Felis manul). From the lake area, there is a view of the Altai Mountains; potentially the place may turn out to be interesting from the point of view of ecotourism.^[1]

Due to the six species of birds breeding in the surrounding areas, the lake, along with Khar Lake south-east of Dayan lake and coastal areas, was considered a bird sanctuary. Six species nest around the lakes that BirdLife has identified as key. One, the saker falcon (Falco cherrug), is in danger of extinction, and the white-throated bush chat (Saxicola insignis) is in danger. The other three are considered to be of least concerns; they include: northern lapwing (Vanellus vanellus), lesser kestrel (Falco naumanni) and bar-headed goose (Anser indicus).^[1]

Climate

The climate is cold.^[2] The average temperature is -5 °C. The warmest month is August, at 14 °C, and the coldest is December, at -24 °C.^[3] The average rainfall is 278 millimeters per year. The wettest month is July, with 55 millimeters of rain, and the driest is February, with 6 millimeters.^[4]