Buir Lake is one of the largest freshwater lakes in Mongolia. The lake is located on the
border with China, with a narrow band of the northwest of the lake extending into Chinese
territory. There are extensive areas of wet grassland, reed beds and willows in the Khalkh
River delta. There is only one outfl ow from the lake: the Orshuun River. The lake is frozen between November and the end of April. There are sand dunes at the southern end of the lake, containing several small lakes, and with steppe habitat beyond them. The site is an important area for fishing, and illegal fishing from the Chinese side is often reported. There are some recreational and tourism activities at the site, which is located along the main road from Choibalsan to Khalkhgol soum, and the number of visitors is increasing. Buir Lake and its surrounding wetlands were nominated as a Ramsar Site in 2004.
Globally Threatened species found at Buir Lake comprise Oriental Stork Ciconia boyciana (EN), Swan Goose Anser cygnoides (EN; in summer 2002, over half of the global population was recorded on the lake), Baikal Teal Anas formosa (VU), Pallas’s Fish-eagle Haliaeetus leucoryphus (VU), Lesser Kestrel Falco naumanni (VU), Siberian Crane Grus leucogeranus (CR), White-naped Crane G. vipio (VU), Great Bustard Otis tarda (VU) and Relict Gull Larus relictus (VU). The site supports an assemblage of species restricted to the Eurasian steppe and desert biome. The site also supports at least 1% of the flyway
populations of Great Crested Grebe Podiceps cristatus, Great Cormorant Phalacrocorax carbo, Grey Heron Ardea cinerea, Swan Goose Anser cygnoides, Ruddy Shelduck Tadorna ferruginea, Common Shelduck T. tadorna and Northern Lapwing Vanellus vanellus.
Non-bird biodiversity: Mongolian Gazelle Procapra gutturosa, Eurasian Otter Lutra lutra and Taimen Hucho taimen are a few of the nationally threatened species that inhabit the site. Large herds of Mongolian Gazelle frequent the area south of the lake all year around.