BACTERIOLOGICAL WATER QUALITY OF SURFACE SPRINGS AROUND LAKE OHRID

The ancient Lake Ohrid is an oligotrophic, cold oligomictic, calcareous, graben, mark lake, mostly fed with spring water from the numerous sublacustrine and coastal sources. Besides tributaries, the main input comes from the numerous karstic springs around the lake. The bacteriological quality of spring waters around Lake Ohrid were evaluated. Samples were collected from 8 natural springs (St. Naum, St. Petka, St. Bogorodica, Korita, Elsani, Biljanini, Hydrobioloski and Kalista springs) and analysed for total coliforms, enterococcus bacteria, Escherichia coli, Clostridium perfringens and parameters of ecological aspect (heterotrophic, proteolytic, amilolytic, lipolytic and phosphorusmineralizing bacteria). Standard methods were used, with general and selective nutrient media and membrane filter method.Based on results, received from the bacteriological analyses of surface springs around the Lake, in general, from ecological aspect, we can conclude that all the investigated parameters have values characteristic for pure spring water. This state is a result of a low biodegradable organic matter concentrations. The total bacterial counts (heterotrophs) ranged from 18 to 612 bact.ml-1. The values obtained for bacteria which mineralize organic matter of protein, sugar or fat origin are small or insignificant. Also, phosphorusmineralising bacteria suggests a small concentrations of phosphorus. The coliform organisms, although in small amounts, were present almost in all springs. Enterococci and E. coli occur occasionally after rainy periods. Three springs were heavily contaminated. Bazed on criteria which used the ratio of faecal coliform to faecal streptococci, all springs studied may be contamined with human and animal wastes. It is concluded that the spring waters studied are unsuitable for human consumption unless disinfected.