As one of the last pre-Alpine lakes, Lake Constance has a water level dependent on seasonal fluctuations. The difference in the normal course of the year ist about 2 metres. This favours near-natural vegetation zoning, as well as shallow water and reed zones close to the shores. Reed-covered shores are a valuable and species-rich habitat.
It offers space for birds, insects, fish and amphibians. Together with the mussels living in the water, the up to 5m high reed plants also clean the water – a kind of biological sewage treatment plant for the lake.