This dataset identifies estuaries that are vulnerable or susceptible to the impacts of land-based inputs of pollutants such as urban stormwater or agricultural runoff. A higher level of management intervention is needed to protect, maintain and/or restore the water quality and ecological condition of vulnerable estuaries from these inputs.

The vulnerability arises from inherent characteristics of the estuary that can determine where and how much the pollutants are transported and retained in the estuary. Inherent characteristics include catchment area, estuary surface area, estuary volume, estuary depth and the estuary entrance opening and closing regimes. All of these characteristics combine to influence the estuary hydrology such as tidal flushing, dilution capacity, and retention. For example, the vulnerability of estuaries that are classified as Intermittently Closed and Open Lakes and Lagoons (ICOLLS) is predominantly dependent on their state of connection to the sea which determines the rate of flushing. Those with a small catchment to waterway area ratio will have limited connections to the sea as a result, and will be relatively more susceptible.