Variation in estuary type, entrance condition, catchment characteristics and climate along the NSW coast produces estuarine ecosystems that are complex, dynamic and variable. As estuaries slowly infill, and as development further increases sediment and nutrient inputs, excessive levels of nitrogen or phosphorus in the estuary can cause algal blooms ('eutrophic' conditions) and other harmful effects that adversely impact ecosystems as well as human usage.
To adequately capture ecosystem complexity, a number of ecological indicators are being used to report estuary health covering eutrophication, habitat and fish.
