Identification of wintering waterbird high tide roosts on the Severn Estuary SSSI/SPA completed in four phases: Phase 1 includes the Brean Down to Clevedon stretch. Phases 2 & 3 were completed at the same time. Phase 2 included the Clevedon to Oldbury stretch and Phase 3 Bridgwater Bay. Phases 2 & 3 also identified the subsites within Steart Marshes in Bridgwater Bay. Phase 4 includes the Gloucestershire area. This is a spatial dataset that identifies the locations of waterbird high tide roost sites in the Severn Estuary; and characterises the habitat(s) and waterbird composition. Information on the presence of waterbirds and their roost site characteristics was collected for each sector from the following sources: (i) WeBS core count (ie, high tide) data supplied by the BTO; (ii) interviews with the relevant WeBS counter; and (iii) site visits. This study provides much more detailed information than is generally available for the BTO collected WeBS data. The roost locations will help to determine whether the activities associated with a proposed plan or project could lead to impacts which have a significant adverse effect upon any given species or assemblage of water bird(s). Full metadata can be viewed on data.gov.uk.