Water resources are rivers and lakes. Surface waters satisfy up to 90% of the republic’s economics. The biggest water consumer is the republican agriculture (up to 60%). As for industry more than half of the consumed water resources are used by cellulose and paper production and heat-and-power engineering. There is economic fishing in big lakes such as the Gusinoye, the Bolshoye Yeravnoye, the Baunt and the Kotokelskoye.
On the territory of Buryatia there are more than 25 thousand river with the total length of about 125 thousand km. 9% of the rivers are of the category of the smallest (over 10 km long), 25 rivers are of the category of the smallest (less than 10 km long). The rivers of Buryatia belong to 3 big water basins: Lake Baikal, and the Angara and the Lena rivers. More than half of the territory belongs to the Baikal basin.
The rivers of Lake Baikal basin are the Selenga, the Barguzin, the Upper Angara, the Turka, the Tyya and others. The biggest lake tributary is the Selenga (brings about 60% of the total Lake Baikal inflow) which begins on the territory of Mongolia at the confluence of the Muren and the Ider rivers; the more full-flowing and long Ider is considered to be the flow. At the mouth of the Selenga there is a big delta (546 sq. km). The Selenga basin rivers waters are used for irrigation, navigation, timber-rafting, waste waters flow, recreation and fishery. There is navigation on the rivers of Selenga, in the lower parts of the Chikoi and in the mouth of the Khilok (the navigation ways are 282 km long). At the Selenga and the Uda sand and gravel mixture is mined.
On the small rivers about 40 water reservoirs and ponds are built which are for agricultural arable lands in dry years. The water reservoir on the Timlyui (the Kabansk district) is used for industrial water supply of the Kamensk industrial hub. The Lena basin are North Pribaikalye rivers: the Right and the Left Mama (the Severobaikalsk district), the Vitim and the Chuya (the Baunt and the Muisky districts). The Vitim is one of the main tributaries of the Lena in its upper reaches. On the Vitim basin rivers there is mining of loose gold deposits and heat-and power engineering is possible.
The Angara basin rivers are the Irkut, the Belaya, the Kitoi, the Urik and the Oka. The waters of the Irkut and the Oka basins are used for agricultural water supply and irrigation. In the basin of the Kitoi there is gold ore mining (the Zun-Kholbinskoye deposit).
On the territory of Buryatia there are 34,422 lakes with the total area of 267 sq. km (including Lake Baikal). Half of the lakes are in the active drainage area of Lake Baikal. Small lakes with the water surface area less than 0.5 sq. km prevail, only 16 lakes have the area of over 10 sq. km. The biggest lakes of Buryatia are the Gusinoye (163 sq. km), the Baunt (111 sq. km), the Bolshoye Yeravnoye (104 sq. km), the Kotokelskoye (68.9 sq. km), the Oron (63.6 sq. km), the Maloye Yeravnoye (60.5 sq. km), the Arangatui (54.2 sq. km), the Busani (36.8 sq. km), the Isinginskoye (33.4 sq. km), the Isinga (Khorga) (31 sq. km), the Sosnovoye (24 sq. km), the Malye Kapelyushi (20.3 sq. km), the Frolikha (15.4 sq. km), the Gunda (11.9 sq. km), the Irkana (11.7 sq.km) and the Amut (10.7 sq. km). The origin of the lakes is different: from tectonic to eolian. Lakes in former river-beds (flood-land) prevail which come from river waters. Most lakes are fresh water ones with the mineralization of 100-150 sq. m/l, within dry regions there groups of mineral or salty lakes.