The Site is an area of freshwater lakes, reed lands, forested marshland and grasslands, which make up one of the few remnants of an extensive peat bog landscape. In 2014 the boundaries of the Site were adjusted to those of the Natura 2000 site, resulting in a reduction of 376 hectares. It supports rare and endangered species of birds, fish, amphibians, reptiles and butterflies, making it important for maintaining the biological diversity of the Atlantic biogeographic region. Moreover, the Site is an important breeding, staging, moulting and wintering area, supporting more than 20,000 birds and up to 1% of the population of barnacle goose (Branta leucopsis) and black-tailed godwit (Limosa limosa). It also plays an important role in flood regulation and groundwater replenishment. As well as water management, the Site is used for farming, commercial fisheries, oil and gas extraction, and recreational activities such as angling and nautical sports. The main threats derive from drainage, pollution and eutrophication caused by farming activities, and habitat disturbance due to tourism.