So crucial is Bool Lagoon as a drought refuge and breeding ground for thousands of birds and other wildlife that it is listed with UNESCO as a Wetland of International Importance.
It borders the Bridgwater Bay National Nature Reserve which was designated under the Ramsar Convention as a wetland habitat of international importance and a special protection area.
The agency says the area, near the Slimbridge Wetland Centre, is of "international importance" for migrating wildfowl, breeding waders, migratory fish and Atlantic eels.