ABSTRACT: Microorganisms are a particularly important organic water pollution indicator. Psychrophilic and mesophilic microorganisms, also known as indicators of total contamination, are naturally present in the waters. Total and faecal contamination indicators were monitored in the aquatic ecosystem of the flow Gidra with human activity being the main influence. While microbial counts usually do not exceed the relevant legislative values on Gidra upstream, the middle and lower stream reaches well above these values, suggesting contamination. Qualitative analysis was performed aimed at determining the species spectrum of indicator of faecal contamination in addition to the quantitative part it.