Most estuaries and coastal lakes along the Wollongong coastline naturally open and close to the ocean depending on both rainfall and wave conditions. Over time, the entrance point where these watercourses meet the ocean can shift and become unstable due to tides, waves and catchment runoff. These changes can affect nearby infrastructure, dunes and recreational beach use.

In some locations, structures like training walls or breakwaters have been put in place which alter natural entrance dynamics. This impacts sediment movement and estuary conditions.