Biological assessment is a useful alternative for assessing the ecological quality of aquatic ecosystems since biological communities integrate the environmental effects of water chemistry. Algal and water samples were collected at monthly intervals from three sites of River Mutha (Pune, India). The most pollution tolerant genera and species of four groups of algae were recorded from three sites of River. Nygaard’s and Palmer’s biotic indices have been used for the assessment of quality of the River. Phytoplankton encountered in the water body reflects the average ecological condition and therefore, they may be used as indicator of water quality. The algal flora of polluted water bodies shows the dominance of blue green and diatoms like, Oscillatoria, Lyngbya, Anabena, Microcystis, Navicula, Nitzschia, Synedra, Gomphonema through out the investigation many green algae like, Pandorina, Scenedesmus, Stigeoclonium, Ankistrodesmus, Chlamydomonas, also occur abundantly and frequently
