Vaal Dam remains over 101% full as inflows ease heading into August
· Citizen
Weekly hydrological data from The Reservoir shows steady storage levels and rising barrage discharge as the Upper Vaal system settles after a volatile year.
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The Vaal Dam remained comfortably above full capacity through the week of 27 July to 31 July 2026, according to data released by The Reservoir, the Water Resource Information Centre for the Catchment Management Forums of the Upper Vaal Water Management Area.
The Reservoir noted that the figures were supplied on behalf of Rand Water and the Department of Water and Sanitation, and cautioned that not all abstraction and evaporation losses from the Vaal Dam were reflected in the reported data.
Storage holds above full capacity
Storage stood at 101.89% full on Monday, 27 July, before easing slightly to 101.76% on Tuesday and Wednesday and settling at 101.64% on both Thursday and Friday.
According to The Reservoir’s weekly bulletin, the dam’s storage averaged 101.74% across the week, with a high of 101.89% and a low of 101.64%.
No figures were yet available for Saturday or Sunday at the time of publication, with those cells still marked as pending verification.
Inflow figures trend downward through the week
Inflow into the Vaal Dam showed a gradual decline over the five reported days.
Monday recorded an inflow of 43.5m³/s, the highest figure of the week, before dropping to 40.5m³/s on Tuesday and 39.7 m3/s on Wednesday.
Thursday saw a slight uptick to 41.0m³/s, followed by a dip to 39.6m³/s on Friday, the lowest reading of the week.
The weekly average inflow came to 40.8m³/s, based on figures supplied by The Reservoir on behalf of Rand Water and the Department of Water and Sanitation.
Dam discharge and sluice gates unchanged
Discharge from the Vaal Dam held steady at 16.9m³/s every day from Monday through Friday, giving a weekly maximum, minimum and average that were all identical at 16.9m³/s.
No sluice gates were open on any day during the reporting period, with the count remaining at zero throughout the week.
Barrage discharge climbs sharply on Friday
At the Vaal Barrage, discharge held steady at 15.1m³/s from Monday through Thursday before jumping to 22.6m³/s on Friday.
That Friday spike pushed the weekly maximum to 22.6m³/s, against a low of 15.1m³/s and a weekly average of 16.6m³/s. The barrage water level itself did not move at all during the week, remaining constant at 7.5 metres from Monday to Friday.
Water temperature fluctuates within a narrow band
Water temperature at the barrage varied only slightly across the week.
It opened at 12.5°C on Monday, dipped to 11.8°C on Tuesday, rose again to 12.4°C on Wednesday, peaked at 12.7°C on Thursday, and fell back to 11.8°C on Friday.
The weekly figures showed a high of 12.7°C, a low of 11.8°C and an average of 12.2°C.