Bibliogr. s. 5278-5279. Anna Bojarczuk podpisana: Anna Wolanin

This study was aimed to assess the diurnal variability in the number of microbial indicators of water quality and the content of the selected main ions at 3 sites located on Białka river, Podhale. The examined sites included the stream being a receiver of sewage from the treatment plant, before the treatment plant and few kilometers downstream of the sewage discharge - at the water intake for artificial snowing of the largest ski station in the region. Twelve series of samples were collected over 36 hours period. Temperature, pH, electrical conductivity and dissolved oxygen were measured onsite, microbiological analyses included the numbers of mesophilic bacteria, fecal Escherichia coli and Enterococcus faecalis, chemical analyses determined the concentration of main ions. E. faecalis was not detected in this study, while the concentration of mesophilic bacteria and E. coli varied largely between sites and hours of sampling. The smallest content of microorganisms was observed before the treatment plant and significantly increased at the sewage discharge. It was found that the cycle of the sewage treatment plant operation affects microbial contamination of water both in the stream which receives effluent from the treatment plant and in the downstream part of the river.