The Site is composed of seasonal and permanent freshwater marshes, forested and non-forested peatlands, rivers and streams. It is in the heart of a plateau where the popular mineral waters of Evian have their origin as rainwater is absorbed in the soil. During the infiltration process it is purified and redistributed underground, feeding the aquifer. In addition, this network of wetlands contributes to the maintenance of an exceptional hydrological system, feeding the groundwater that gives rise to Evian’s mineral waters. Although the Site does not support an outstanding number of species, it provides an important habitat for invertebrates, including the nationally endangered butterfly Coenonynpha tullia. The extension of agricultural land and the construction of drainage systems have also led to occasional changes in hydrological functioning.