The “tajchy“ of Banská Štiavnica are greatly influenced by anthropogenic factors that can lead to a reduction in water quality in reservoirs.Of the observed microscopic markers, colonies of bacteria cultured at 22 ° C showed to be the most significant. While research in selected water reservoirs, we did not notice any significant changes in coliform bacterial counts. Our results did not show the occurrence of thermotolerant coliform bacteria or enterococci.The Enterobacteriaceae species analyzed are natural constituents of the microflora of the water and their values of 1-8 cfu / ml do not exceed the set limits. And the species Gallionella sp. and Leptothrix sp., whose values did not exceed the set limits.The G-bacteria of the genus Acinetobacter sp. and Aeromonas sp, of which the most prominent representatives were Aeromonas veronii and Acinetobacter radioresistens were identified by MALDI-TOF MS Method.