Austria is one of a few countries which, for the entire population, obtains drinking water from ground water sources. The occurrence of potentially harmful algal blooms formation in bathing water is recorded in Austria every summer and samples are sent for toxin analysis. This includes deep lakes in the Alps as well as smaller water bodies such as gravel pit lakes and ponds. In Austria any national guideline on the estimation of health risks associated with cyanobacteria bloom occurrence is lacking. As this occurrence is also of public interest, a national effort is needed towards characterizing potential health risks.