A model tool for bathing water quality management: A case study on Salmonella occurrence at the southern Baltic coast

Abstract

Despite Salmonella bacteria being important and wide-spread human pathogenic micro-organisms in coastal waters, they are not used as indicator organisms in the new EU bathing water directive 2006/7/EC. However, this does not exclude Salmonella as a potential threat in European bathing waters. For this reason we are analysing a Salmonella pollution event at the Polish seaside resort Miedzyzdroje in summer 2008 and present here a generic workflow for bathing water quality management developed through our results. We combine water quality measurements and a 3-D ocean model system with the goal to locate possible sources via backtracking simulations. Forward scenario simulations lead to spatial Salmonella pollution maps. A continuous pollution source in town is identified here as the most likely origin of bacterial occurrence. There is a high probability that the contamination impacted beaches within a minimum radius of 10 km from the source. Varied wind scenario results provide transport ranges and therefore the potential to improve the managerial response during a future Salmonella pollution in Miedzyzdroje. The overall impact of hygienic water pollution shows the necessity of new management instruments. Supra-regional recommendations are summarised in the generic workflow. It presents first action recommendations, aimed at safeguarding the health of bathers, in the event of a contamination without implementing a model study. If the pollution is continuous, an extended model study is recommended. Furthermore, the results are able to identify concrete sampling locations, based on regions most affected by the pollution event as shown within the case study.