The Katse Dam in Lesotho is part of the Lesotho Highlands Water Project. Picture: Supplied
The looming shutdown of the extensive water delivery system that transfers water from Lesotho’s highlands to Free State and Gauteng should lead to minimal disruption for consumers, says the department of water and sanitation.
And some experts agree that the impact will be lessened by the fact that the dams in this part of the country are at high storage levels and that their capacity won’t be reduced to critical levels in just six months.
The upcoming maintenance work on the 37km Lesotho Highlands Water Project tunnel will affect the main water supply in Gauteng and Free State as it will affect the flow along the Liebenbergsvlei River and the Vaal River system. The Free State’s municipal water supplies for Mafube, Nketoana and Dihlabeng will also be impacted.
While concerns have been raised that the water scarcity issue in Gauteng could worsen, department spokesperson Wisane Mavasa said the impact of the outage on overall water availability would be insignificant.
She said the transfer to the Integrated Vaal River System (IVRS) is 780 million cubic metres of water a year, and the tunnel closure would affect only 80 million cubic metres.
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“An analysis was undertaken in May last year to assess the risk to the IVRS’ performance as a result of the outage, and to determine the impact of the shutdown on water availability to users in South Africa.
“The results showed that the impact of the outage on the IVRS will be insignificant considering that dams in the IVRS, such as the Sterkfontein Dam and others, are relatively full,” said Mavasa.
Experienced civil engineer Sebasti Badenhorst said: “The department of water and sanitation says there will be no impact. Dams are full, storage is good and they are managing that well. It’s actually good news that they are shutting down the tunnel and doing repair work.”
According to the department, the Sterkfontein Dam releases water to the Vaal Dam when the dam is at 18% capacity or lower.
Based on the department’s analysis, this was not expected to happen during the 2023-2024 operating year, but more analysis will be done next month to ensure there are no water supply risks from the IVRS in the 2024-2025 operating year. Figures from the department show the Vaal Dam is currently 67% full.
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Mavasa said during the shutdown period, water transfers would be reduced, impacting annual transfer volumes. However, measures will be taken to recover the shortfall after the maintenance is completed.
The Lesotho Highlands Water Project supplies about 60% of Gauteng’s demand to a third of its population. Land and agriculture researcher Dr Donna Hornby said its water coverage extended to irrigation water for commercial farms, which would probably be impacted.
She said irrigation and other farming operations depend on steady and dependable water supplies for agriculture.
“In any commercial farming areas that rely on irrigation, [and are affected by the shutdown of the Lesotho Highlands Water Scheme] if they are drawing irrigation from that scheme, their crops will be affected directly.
“We are in the summer rainfall season and are going into the dry period now.
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“Anybody growing rye-grass, which feeds the dairy industry, or who are growing peas, cabbages and winter veg like broccoli and cauliflower – all these farmers will be affected by the closure of irrigation.
“This will directly feed into retail shops if these areas get shut down in terms of irrigation. The extent of the problem around food security will be on how big the area is that will be affected.”
Badenhorst said: “We do not really know what the impact will be, but believe ageing municipal infrastructure is a bigger threat to water security in the cities.
“We do want to encourage the public to become more aware of their water usage and think about alternative water sources, such as rainwater harvesting and emergency back-up water systems.”
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