Severn Estuary. 05/01/76; England, Wales; 24,701 ha; 51°36'N 002°40'W. Special Protection Area, Nature Reserve, SSSI. The estuary has the second highest tidal range in the world and consists of an extensive intertidal zone comprising intertidal mudflats, sand banks, saltmarsh, shingle, and rocky platforms. Flora and fauna communities typical of extreme physical conditions occur at the site. The invertebrate community provides an important food source for passage and wintering waders. The site is of particular importance for staging nationally important numbers of several species of waterbirds, including Tadorna tadorna and Numenius phaeopus, and supports internationally important numbers of various species of wintering waterbirds, including Limosa limosa islandica. This site is important for several species of fish migrating between sea and river via the estuary. Small patches of a nationally rare plant Lythrum hyssopifolia are found in the grassland zone. Human activities include recreation, fishing, and hunting, and a visitors' centre, trails and hides are maintained. Extended on 13/07/95 from the former Ramsar Sites Bridgwater Bay and Upper Severn Estuary. Ramsar site no. 67. Most recent RIS information: 1999.