Estuary surface areas have been defined in a GIS spatial layer on the basis of whether an area is discernible in the 1:25,000 topographic map series available from the Land and Property Management Authority (LPMA). The spatial layer has been merged with the LPMA coastline layer and spatial data from surveys of seagrass, mangrove and saltmarsh. The dataset is available in the form of areas of open water, seagrass, mangrove and saltmarsh extending up to the tidal limits of tributaries.; ; Surface areas were required to support the development of a new chlorophyll response-based estuary classification system based on dilution and flushing characteristics. Nutrient loads were normalised by surface area to enable comparison across estuaries and validate the classification system. The classification system was used to stratify estuaries in NSW for the development of reference conditions and the design of a sampling program of chlorophyll a, turbidity and associated water quality parameters to assess estuary health.; ; Estuary pressures additional to nutrient load, were also normalised by surface area to enable inter-estuary comparison.