The studies on the lakes and streams remote mountainous areas Trans-Baikal region allowed to established new places for species listed in the Red Book of Russia (Sirodotia suecica), rare in the territory of Russia (Prasiola fluviatilis), and common (Hydrurus foetidus). Fragmentation of habitat types due to heterogeneity of landscape-climatic conditions Transbaikalian algological absence research on the greater part of the territory. For the first time specifies for the Trans-Baikal region Lemanea fluviatilis. All species are found at altitudes ranging from 800 to 2000 meters above sea level in cold waters. The limited area of distribution of these species raises the question of their inclusion in the lists of species to consider the protection of their habitat.