This is the level at which acidity being formed in the lake sediments can no longer be neutralized by the alkalinity of the sediments and lake waters. Any water levels below these will expose large areas of acid sulphate soils and any subsequent refilling (including future freshwater inflows or the introduction of
seawater) will likely result in the acidification of the water body.
The current modelled critical acidification threshold water levels are minus 1.5m AHD for Lake Alexandrina and minus 0.5m AHD for Lake Albert. It is predicted the water level of Lake Alexandrina will reach this trigger level by February 2010. These predictions may change as more data is collected and the acidification modelling is improved.