Opening up Deep Creek

Deep Creek estuary is always changing

Deep Creek is an amazing estuary, dynamic and changeable. I spend a lot of time here, swimming, paying attention to Eos and Helios.

All along the NSW coast many coastal lakes and lagoons alternate between being open or closed to the ocean. These are known as Intermittently Closed and Open Lakes and Lagoons (ICOLLs).

Deep Creek opened up naturally on Boxing Day, but unusually closed again quickly. A sand/beach barrier depends on the movement of sand and sediment by the waves,  tides, flood action and wind.

The council does not intervene unless the water level becomes too high (with a risk of flooding) or the water quality deteriorates significantly. Though in this case, footings to the car park were being destroyed.

The danger is that opening a river can result in a rapid release of water into the ocean and an immediate decrease in the river level, leading to oxygen depletion and fish kills. The operation is not lightly undertaken.

Opening up an ICOLL is done at high tide to avoid problems of oxygen depletion.