This study aims to make new and already published data on algae available for regional ecological monitoring. From our research and from bibliographic sources, 2460 species and 3119 subspecific taxa are known, including nomenclatural types of species. The composition is as follows: Cyanophyta, 224 species (271 subspecific taxa); Dinophyta, 83 (94); Cryptophyta, 37 (37); Raphidophyta, 5 (5); Chrysophyta, 155 (164); Xanthophyta, 264 (274); Bacillariophyta, 412 (719); Euglenophyta, 261 (352); Chlorophyta, 1015 (1199). It was not possible to confirm 1950s records of fresh-water Phaeophyta - 1 (1) and Rhodophyta - 3 (3), and these remain known only from the literature (Arnoldi, 1925; Shkorbatov, 1926). The ten algal families which account for 50.7% of all species are: Desmidiaceae (10.5%), Euglenaceae (10.3%), Naviculaceae (8.5%), Chlamydomonadaceae (3.9%), Coelastraceae (3.75%), Oscillatoriaceae (3.21%), Closteriaceae (3.01%), Nitschiaceae (2.82%), Pleurochloridaceae (2.53%), Characiopsidaceae (2.15%). Distribution of algal species in various types of waters shows considerable variation. The biggest number of taxa - 1852 (2233) - was recorded in natural still and slow flowing waters: flood plains, water meadows and bogs. In small rivers 1369 (1737) taxa were collected. In fish ponds and amenity lakes 1292 (1579) are known. The least diverse are algae in reservoirs with 995 (1228) taxa.