The area consists of a brief stretch of the river Dora Baltea and of its alluvial plain, and here you can find the habitat of "Residual alluvial forests of Alnion glutinoso-incanae", the only formation of this kind between Courmayeur and Aosta. The reserve is used as a rest area by migratory birds typical of the wetlands; together with Les Iles of Saint-Marcel, it is a shelter for aquatic birds in an inner area of the Alpine chain. As a matter of fact, the area plays an important role for the migratory birds which have abandoned their route and must cross the Alps in their highest points. The species nesting in the reserve are the mallard, the moorhen, and the marsh warbler; among the birds of passage there are the purple heron, the grey heron, and the bittern.
The vegetation is characteristic of environments rich in water and characterized by hygrophile bank woodlands and canebrakes. The woodland is dominated by Alders, White Willows, and Black Poplars and the humid underwood by Dogwoods (Cornus sanguinea) and Meadowsweets (Filipendula ulmaria). The eastern side mainly consists of canebrakes, in particular Common Reed (Phragmites australis) together with reed canary grass (Typhoides arundinacea), Common Cat Tail (Typha latifolia), and Greater Tussock-sedge (Carex paniculata).
The Nature Reserve represents the ideal place where migratory birds can stop during their journey through the Alps. Among the migratory and the nesting birds in the Reserve there are the Mallard, the Moorhen, the Grey Wagtail, the Cuckoo, and the Blackcap. In spring and autumn there are also other guests such as the Little Grebe, the Great Crested Grebe, the Grey Heron, the Tufted Duck, the Reed Bunting, the Hoopoe, the Little Ringed Plover, the Black-headed Gull, and many others.