The Site is a dammed estuary, which was part of the Wadden Sea until it was closed off in 1969. It includes a shallow freshwater lake, marshes, wet grasslands and arable lands. The Site boundary was aligned with that of the Natura 2000 Site in 2014, with a road and parking areas on the north side excluded, reducing the area by 36 hectares. It hosts more than 20,000 wintering birds and over 1% of the biogeographic populations of nine species of waterbirds. The Site supports threatened mammals such as the otter (Lutra lutra) and pine marten (Martes martes), and endangered breeding birds such as the ruff (Philomachus pugnax), bittern (Botaurus stellaris) and Montagu’s harrier (Circus pygargus). It plays an important role in water supply and the maintenance of the hydrological balance of the region. Human activities include tourism, commercial fishing, shipping, boating and farming. The main threats to the Site’s ecological character are the disturbance of birds by military training and tourism, non-industrial pollution and eutrophication.