ABSTRACT Among the complex of anthropogenic factors, one of the leading places is occupied by the "water factor" associated with pollution of water sources, shortcomings in water purification and disinfection. Discharge of insufficiently treated and untreated wastewater into watercourses predetermines abnormal changes in their chemical composition and degradation of biocenoses. Background and Aim: Municipal wastewater contaminated with organic and nitrogenphosphorus-containing compounds, as well as bacteria and viruses, also contribute to the pollution of water bodies. The main factor affecting the change in the quality indicator of water bodies is municipal wastewater. In the treatment facilities of Bukhara, about 20 thousand m3 of wastewater, which will lead to a change in the chemical and biological composition of water. At the same time, there is no complete picture of the distribution of algae and their role in determining the ecological and sanitary state of biological ponds of the treatment plant in Bukhara, which prompted us to study these important problems. Material and Methods: Processing of the collected algological material was mainly carried out in the laboratory of algology and hydrobotany of the Institute of Botany of the Academy of Sciences of the Republic of Uzbekistan and was also partially processed at the Department of Botany of the University of Bukhara. The physicochemical composition of wastewater in biological ponds was determined by the generally accepted methodology of A. S. and Yu. Yu. Lurie. Conclusion: According to our observations, representatives of all systematic groups of algae developing in a particular reservoir participate to varying degrees in the processes of self-purification of wastewater. Even species of the same genus are characterized in different ways. This indicates the need for comprehensive and deep floristic studies of the natural algal population of water bodies used as biological ponds - reservoirs, sedimentation tanks and filtration fields.