Vaal Dam: The Vaal Dam’s third sluice gate has been reopened amid high inflows due to the continued heavy rainfall in the upper catchment.
According to South African Government News Agency, the third sluice gate was reopened on Wednesday at 4pm to manage water outflows at the dam, which operated with two sluice gates since last week, 16 April 2025. The Department of Water and Sanitation stated that the opening of the third sluice gate will increase the outflow from 299.59 cubic metres per second (m3/s) to an estimated 400 m3/s.
The department revealed that the current water inflow is estimated at 943 m3/s and the water level at the dam is at 108.4% as of midday Wednesday. There is a possibility that another sluice gate will be opened on Thursday should the inflows continue to increase.
Adjustments have also been made at Bloemhof Dam, where water outflows were increased from 500 m3/s to 650 m3/s at 10am, and to 800 m3/s at 12pm on Wednesday, in anticipation of the measured incoming flows upstream. These adjustments are necessary to manage the continuous rising inflows and safe operation of the dam, which was at 106.71%.
As of Wednesday afternoon, the inflows into Bloemhof Dam were estimated at 640 m3/s. The department indicated that the inflows are likely to increase over the next 24 hours, with potential plans to further increase releases on Thursday morning.
The department also noted that all the sluice gates remain closed at Grootdraai Dam, where the storage capacity is still at 104.92%, with inflows of 32.44 m³/s. The controlled water releases at both the Vaal and Bloemhof Dams have led to overtopping of riverbanks downstream, resulting in flooding that has affected settlements in lower-lying areas within the 1 in 100-year floodline.
Residents living within the floodline of the Vaal River downstream of the Vaal and Bloemhof Dams, who have evacuated, are advised to continue avoiding the flooded areas as the river catchment remains oversaturated. With more rainfall predicted in the Upper Vaal Catchment, the department emphasized that it will continue to monitor inflow water levels in the Integrated Vaal River System (IVRS) to ensure necessary precautions are in place in line with dam safety standards and hydrological monitoring systems.
Sluice gates are opened for controlled water releases when dams exceed full capacity, to prevent potential infrastructure failure that could lead to a dam bursting. The department implements these controlled water releases as part of safety precautions to safeguard the infrastructure and protect human life.