The Katse Dam, on of the two feeder dams of the Lesotho Highlands Water Project. Picture: Lesotho Highlands Development Authority
A six-month maintenance shutdown of Gauteng’s water reserves begins on 1 October.
The Lesotho Highlands Water Project (LHWP) provides the water that feeds the system that keeps Gauteng’s taps running.
Rand Water draws its product from the Integrated Vaal River System (IVRS) which receives 780 cubic metres worth of supply from the Katse and Mohale dams from across the border via the LHWP.
The Vaal Dam is one of 14 dams that make up the IVRS and is the primary feeder for Rand Water, who draw from the Sterkfontein Dam should the Vaal drop below a certain level.
“The standard operating rule is that Sterkfontein Dam releases water to the Vaal Dam when the Vaal Dam reaches a level below 18%,” Sanku Tsunke, Department of Water and Sanitation (DWS) Communication Services confirmed to The Citizen.
As per weekly dam level figures issued by the DWS, the Vaal Dam was at 41.9% of its full storage capacity (FSC) of 2.5 billion cubic metres.
Sterkfontein Dam was listed as being at 98% of its 2.6 billion cubic metre FSC, as per the 23 September reading.
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Rain is expected to supplement the dam levels, while DWS believe there is a slim chance of needing the Sterkfontein reserves.
“There is a 95% probability that there will be sufficient water in the IVRS (excluding Sterkfontein Dam) during the tunnel closure period,” said Tsunke.
“Should the 5% risk materialise, then DWS will release water from Sterkfontein Dam into the Vaal Dam,” he added.
Maintenance on the LHWP tunnels is due to be complete by 30 March, with both the South African and Lesotho governments confident about the deadline.
DWS claim the maintenance will give the tunnels another “20 to 30 years” of operational performance.
“Comprehensive technical and operational plans have been put in place to ensure minimal disruption to the everyday lives of the people in both countries,” stated DWS.
Rand Water has issued level-one water restrictions, and all departments have urged residents to conserve water.
The Trans-Caledon Tunnel Authority (TCTA) is the entity responsible for the South African side of the LHWP.
ALSO READ: Water crisis: Level 1 restrictions implemented as demand targeted
TCTA Head of Communications, Wanda Mkutshulwa explained that 100 million cubic metres would be released from Lesotho into the IVRS before the shutdown.
“However, it is still expected that, despite this additional allocation, there will be a minor shortfall of transfer for the LHWP of approximately 80 million cubic metres,” Mkutshulwa confirmed to The Citizen.
One cubic metre is equal to 1 000 litres, while a megalitre refers to one million litres.
DWS’s Tsunke said Rand Water supplied Gauteng with roughly 156 000 megalitres a month, or 156 billion litres per month.
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