Assessment of water quality of the Selenga river by bacterial number

We have assessed the water quality of the Russian section of the Selenga River based on standardized indicators (total number of bacteria and the number of organotrophic bacteria). The waters of the Selenga River are characterized by a very high total number of bacteria (up to 11 million cells/ml), but a low number of organotrophic bacteria (up to 264 CFU/ml). The highest values we have observed in the area of Ulan-Ude, which, like the increased number of hydrocarbon-oxidizing bacteria, testifies to a negative impact of the city. According to these indicators, river water is assessed as “dirty” (total number) and “very clean” (number of organotrophs). The ratio of the total number of bacteria and the number of organotrophs allows us to rate the water as “clean”. The low number of hydrocarbon-oxidizing bacteria and the absence of phenol-oxidizing bacteria indicate the absence of specific pollutants.