The delta of the Orkhon and Selenge Rivers is formed at the junction of the two largest rivers in Mongolia. The surrounding areas support wet grassland, steppe and mountain steppe. The Orkhon-Selenge region is the most important agricultural zone in Mongolia, and there is a lot of cultivation and human settlements along the river valleys. The most serious threat to biodiversity at the site is the discharge of waste, including heavy metals from nearby gold mines. A further concern is human settlement on islands in the rivers. Many fallow fields have been abandoned, which is resulting in the loss of top soil.
The site supports the following Globally Threatened bird species: Swan Goose Anser cygnoides (EN); Baikal Teal Anas formosa (VU); Lesser Kestrel Falco naumanni (VU); and Great Bustard Otis tarda (VU). The site also supports at least 1% of the flyway populations of the following congregatory waterbirds: Bean Goose Anser fabalis; Greylag Goose A. anser; Ruddy Shelduck Tadorna ferruginea; and Demoiselle Crane Anthropoides virgo.
Non-bird biodiversity: Nationally threatened mammal species, including Red Fox Vulpes vulpes, Corsac Fox V. corsac, Grey Wolf Canis lupus and Siberian Marmot Marmota sibirica (EN), are commonly seen at this site. Furthermore, nationally threatened fish species, such as Mongolian Grayling Thymallus revirostris, Lenok Brachymystax lenok and Taimen Hucho taimen, occur in the rivers.