Posidonia australis is listed as endangered in eight NSW estuaries under the Fisheries Management Act 1994 or the EPBC Act due to historical losses and ongoing impacts. Posidonia occurs in 17 estuaries in NSW, from Wallis Lake down to Twofold Bay, and is also found in some sheltered, open coast locations. Estuarine meadows of Posidonia have been mapped on multiple occasion NSW DPI since 1980 and here we present data on how the extent of these populations has changed over time. Patterns of change in Posidonia differ greatly among and within estuaries. There have been ongoing losses and fragmentation of Posidonia in some urbanised estuaries and increases in some less urbanised estuaries. Apparent temporal stability in Posidonia area at the estuary-scale can mask smaller-scale losses which are offset by Posidonia increases in other parts of the estuary. Data on threats to Posidonia are now also being compiled to help inform management of the seagrass and we will provide a summary of the recent trends for some threats.