The researches of different types of lakes and reservoirs of South Ural have revealed a diversity of Cyanoprocaryotaand its determining contribution in phytoplankton. Seasonal dynamics of phytoplankton biomass is found out of two water bodies’ types: eutrophical and mesotrophical. There are different types of phytoplankton: a gloeotrichia type, an anabaena, and the mixed one. The presence of plankthotrix type in one lake was marked. The expansion of a SI-type phytoplankton was not observed for the period of research, but some species of SI complex have high activity.