Averto Valley came into being as a result of the modifications of the territory carried out by the Serenissima Republic starting in the 17th century, culminating with the digging of the Novissimo Canal of the Brenta River, which established the boundaries between the mainland and the lagoon basin. The State Nature Reserve WWF Oasis of Valle Averto is located within a Special Area of Conservation (IT3250030) and Special Protection Area (SPA IT3250046). Since 1989 it has been a wetland of international importance recognized under the Ramsar Convention.
The area, about 200 hectares, includes large expanses of brackish water, reed beds, wet meadows, hygrophilous forests and canals. It is located in the middle to lower part of the Venice Lagoon. The considerable diversification of habitats is related to the saline gradient, different soil elevations and different substrate. The presence of fresh and brackish water, typical of fishing valleys, ensures significant environmental diversity, with about 400 species of flora and numerous plant habitats. Within the oasis are two priority habitats included in the Habitats Directive, such as Limestone Marshes with Cladium mariscus and Alluvial Forests of Alnus glutinosa and Fraxinus excelsior.
Averto Valley is recognized as one of the most important areas in the Venice Lagoon for wintering, migration and nesting avifauna. About 250 species of birds are present, including nesting marsh harrier, black-winged stilt, common tern, bittern, night heron and little shrike. Recent surveys have shown a notable presence of the European marsh tortoise.
