The ecological state of the Pyasina river basin was assessed by the microbiological and chemical composition of surface waters. The waters of the Bezymyanny (Nadezhdinsky) stream, the Daldykan, Ambarnaya, Pyasina, Dudypta and Tareya rivers, Pyasinsky lakes were studied. The content of oil products, sulfate ions, copper, nickel, iron and manganese in water was identfied. The microbiological composition of waters was analyzed and saprophytes, oligotrophic plants, bacteria oxidizing individual hydrocarbons and oil were isolated. It is shown that the aquatic ecosystems of the Norilsk industrial region are exposed to technogenic impact with subsequent local anomalies in pollutant concentrations. The ecological state of the studied reservoirs was determined by the number of saprophytic bacteria.