The intensive development of the oil and gas industry in the northern regions of Russia contributes to a sharp increase in the anthropogenic load on the natural ecosystems of the Arctic. The microflora of thermokarst lake is mainly represented by psychrophilic saprophytes, oligotrophs, ammonifying, and denitrifying bacteria. In the Arctic regions, the processes of biodegradation of hydrocarbons, with the participation of native hydrocarbon-oxidizing microflora, do not have time to fully develop, and the universal biologics used in the petroleum industry have low efficiency at low temperatures. In connection with the indicated problem, the aim of the present study was to investigate the ability of indigenous microorganisms of the Arctic natural waters to degrade oil. The analysis of the obtained experimental data showed that microorganisms which were cultivated under low temperature conditions (5 °C) did not show growth not did they degrade the oil. It is shown that the oil degradation process starts at 10 °C and above, and that the maximum biodegradation intensity is observed in the first 15 days.