The Site consists of a freshwater lake of some 17 by 13 kilometres, surrounded by permanent and seasonal marshes and pools, and by irrigated and seasonally inundated agricultural land. The lake’s surface area of some 5,800 hectares typically increases by an additional 4,000 ha as the land floods in the rainy winter season. The Site’s great importance as a nesting and wintering place at the beginning of the 20th century was reduced by drainage works during the colonial era, and has not entirely been regained in recent years. Nonetheless, the Site hosts in the average winter more than 30,000 waterbirds. It is also a feeding area for Anatidae and coots, including greylag goose Anser anser and Eurasian wigeon Anas Penelope. Agriculture and pasturage are practiced in the Site, and the expansion of agricultural area is seen as a potential threat.