Anomalous colourations in surface water bodies: causes and examples reported by the Regional Agency for Environmental Protection and Energy of Emilia Romagna (ARPAE)

Surface water can exhibit a range of colours beyond the expected blue or green. These anomalous colourations can be triggered by different factors, both natural and anthropogenic, and not always are signs of pollution. This note explores the phenomenon of water discolouration, focusing on natural causes and analysing how factors such as algal and bacterial blooms influence water colour. The study provides examples of specific events that occurred in the Emilia-Romagna region and documented by ARPAE and highlights the importance of monitoring these colouration events in order to provide valuable insights into the health of water bodies and the surrounding environment.