This complex of shallow freshwater lakes, pools and canals, fens, reedbeds and swamp forests surrounded by wet meadows and marshland is the oldest Dutch nature reserve. The area is important for waterbirds such as purple heron (Ardea purpurea) and black tern (Chlidonias niger). It supports vulnerable populations of fish, molluscs and dragonflies. The surrounding area is densely populated and dedicated to agriculture. The main threats to its ecological character are related to drainage, water extraction, pollution and disturbance caused by tourism and a railway. Land use is dedicated to water management and recreation. Around the lake there is a 17-kilometre path which leads to birdwatching shelters and a visitor centre. In 2014 the Site boundary was adjusted to that of the Natura 2000 site, resulting in an increase in area of 452 hectares.