This Site, the second-largest inland wetland in Tuscany, extends over a vast agricultural plain which was created by the reclamation in the 19th century of a large lake and marsh system that stretched for about 40 square kilometres between the Monti Pisani range to the west and the Cerbaie hills to the east. Despite the reclamation works and cultivation, the area still preserves residual natural and semi-natural marsh habitats, with zones of temporary, seasonal or permanent flooding. Due to its size and its position relative to other wetlands such as Lago di Sibolla and Padule di Fucecchio, it is a biodiversity hotspot. The Site plays a crucial role as a stopover for migratory and wintering birds, and despite water regulation and pollution from agriculture and industry threatening the ecosystem, many wetland plant and animal species are found, including the giant snowflake (Leucojum aestivum) and the Italian crested newt (Triturus carnifex). The Site is also a Special Area of Conservation under the European Union Habitats Directive, among other designations.