This paper provides an information about the rare for Siberia  Ruppia maritima L. and Ruppia cirrhosa (Petagna) Grande communities. Ruppia maritima  cenoses have been observed in small, shallow lakes with salinity 28,8-53,3 g/dm³, Ruppia cirrhosa  communities have been found only in Shunet Lake (salinity 11,8 g/dm³). Ruppia communities have been attributed to the relevant associations of  Braun-Blanquet approach – Ruppietum maritimae Iversen 1934 and Cladophoro-Ruppietum cirrhosae Verchoeven 1980.