The Vaal Dam was sitting below 29% capacity just three months ago.
The step was taken due to a strong inflow from the Upper Vaal which is rapidly filling the Vaal Dam.
The strong inflow of water and weather forecasts that still predicted rain apparently contributed to this decision.
The water that now flows through the open locks is destined for the Bloemhof Dam, and makes way for more water that can flow to the Vaal Dam.
According to the latest figures, the dam was already more than 103.5% full and with the weather system currently hanging over the Mozambique Channel, there is the possibility of more rain.