The original idea of building a weir at Pomanda Island was to maintain the pool height for the water intakes for Adelaide. This structure would be different from the locks upstream by having a spillway over which water would flow into the Lakes for most of the time and only be retained if water levels fell below the level of the spillway.
Since the drought has continued and the spectre of acid sulphate soils has loomed, the possibility of opening the barrages to the sea has made the building of a weir more likely, and absolutely necessary if this happens. Other weirs have also been proposed, such as one to protect the freshwater environment of the River Finniss.
by Elizabeth Gordon-Mills, Phd