The Coorong, South Australia, is a globally significant wetland system, listed in the Ramsar Convention under a number of different criteria, including its importance to waterbird populations. Based on annual waterbird censuses conducted between 2000 and 2007, spatiotemporal analyses revealed that significant differences in waterbird community structure exist along the length of the Coorong. This spatial diversity in community structure was also found to be temporally consistent over this 8-year period. The abundance of the most numerically dominant bird species, such as red-necked stint Calidris ruficollis and grey teal Anas gracilis, explained much of this spatial variation. However, comparisons between data collected for the Coorong south lagoon in 1985 and 2000–2007 show that dramatic changes in these waterbird communities have occurred over longer periods of time, with 23 of the 27 most common species having declined in this period by at least 30%. The Coorong still regularly supports globally important populations (>1% of global population) of nine waterbird taxa, including three Palearctic shorebirds, confirming its Ramsar status. The functional links between the overutilized Murray-Darling basin river system and the Coorong are discussed.