The Site comprises a large shallow lake with extensive reed marshes, floodplains, and a human-made island (Vogeleiland). The Site boundary was adjusted in 2014 to reflect the Natura 2000 site; Noordoostpolder dyke was excluded and the area calculated more accurately. It is an internationally important area for wintering and foraging waterbirds such as purple heron (Ardea purpurea) and Savi’s warbler (Locustella luscinioides). In addition, the Site supports endangered species of mosses and plants which are important for maintaining the biological diversity of the Atlantic biogeographic region. It plays an important role in flood control, and sediment and nutrient retention. Human activities include commercial fishing, shipping, nautical sports and water management. The main threats to the Site’s ecological character derive from the construction of dykes and dams, from reed cutting and nutrient pollution.