Lake Illawarra is located approximately 8km south of Wollongong. The Lake is a coastal lagoon formed as a result of the change in ocean level during the Pleistocene period. The last rise in sea level was dated 6000-6500 years ago and since the time of submergence, the area of the Lake has decreased about 17% and sedimentation has filled out about 90% of the original basin.
The present Lake is linked to the sea via an entrance channel 3.2km long, the mouth of which changes continuously in position, shape, depth and width, depending on rainfall, wind and wave action. Consequently, lake-ocean exchange is restricted and there is very little tidal effect extending into the Lake (see Figure 1).