Major six-month shutdown of critical water supply starting soon – what you need to know
A six-month maintenance project on the Lesotho Highlands Water Project (LHWP), a crucial water source for the country’s industrial heartland, is set to begin next month (October 2024) and will last until March 2025.
The Department of Water and Sanitation (DWS) said that the tunnel closure’s effect on the Integrated Vaal Reservoir System (IVRS) will be “minimal” because most dams are relatively full.
An update from the DWS on 19 September outlined that IVRS is currently stable at 76.6%. Last year at this time it was at a more satisfactory 92.4%.
As a result, they have urged “all water users who will be affected by the planned tunnel maintenance to use water sparingly during this period, as a means of managing any unforeseen risks.”
A water restrictions notice is being prepared in this regard.
What is the LHWP?
The LHWP is a collaborative water supply initiative with a hydropower component, developed by Lesotho and South Africa in which water is diverted from the highlands of Lesotho to South Africa’s Free State and greater Johannesburg area.
Ifedotun Aina, a Senior Researcher in the Water and Production Economics Research Unit at the University of Cape Town explained that the project is designed to transfer over 1.27 billion cubic metres of water annually from Lesotho to the IVRS.
“To visualise this amount, imagine about 508,000 Olympic-sized swimming pools filled to the brim every year,” said Aina.
Phase 1, launched in 1998 and completed in 2003, includes the Katse Dam, Muela power station, Mohale Dam, and 82 km of tunnels, transferring 780 million cubic meters of water annually to the IVRS (Free State and the greater Johannesburg area.)
Phase 2, currently under construction, consists of a 165-meter high Concrete Faced Rockfill Dam at Polihali and a 38 km concrete-lined gravity tunnel connecting Polihali Dam to Katse Dam.
Once finished, this phase will add an additional 490 million cubic meters of water per year from the Orange (Sengu) River in Lesotho to the IVRS in South Africa.
Aina explained that the LHWP is “a lifeline to millions of South Africans.”
For example, it:
- Satisfies 60% of Gauteng’s water demand;
- Supplies the irrigation water for commercial farms;
- Supplies water to regions with irregular rainfall patterns and frequent drought;
- Plays a role in public health by delivering clean water to millions of people;
- Contributes to environmental conservation.
What is the maintenance work being carried out?
The tunnel system of the LHWP consists of a Transfer Tunnel, linking Katse Dam with Muela Power Station and Muela Dam, and a Delivery Tunnel, linking Muela Dam with the Ash River Outfall Works between Clarens and Bethlehem.
Tunnel inspections and maintenance occur every five to ten years, with the last maintenance conducted in 2019. That inspection revealed urgent, extensive maintenance is needed for the steel liners on both the South African and Lesotho sides.
“This much-needed maintenance is critical to maintain the integrity of the delivery tunnels as a tunnel failure will risk the transfer of the 780 million m3/annum of water to the IVRS, from which Rand Water draws water to supply its customers,” said a spokesperson from DWS.
“The six months period required to conduct maintenance is thus crucial to avoid any catastrophic event which may result from a lack of maintenance,” they added.
According to the DWS, the work required to be undertaken during the shutdown period includes:
- Grit-blasting the steel-lined section around the entire circumference;
- Re-applying corrosion protection on the tunnel lining;
- Other maintenance and repair work identified during the 2019 maintenance shutdown.
“This work is expected to protect the infrastructure for another 20-30 years,” added the spokesperson
The Lesotho Highlands Water Commission will oversee this maintenance, and DWS is working with the Lesotho Highlands Development Agency and the Trans Caledon Tunnel Authority to complete this project.
The work will be conducted in phases. In the first month, the tunnels will be emptied in preparation for four months of maintenance and repairs. The last months will be spent inspecting and refilling the tunnels with water.
What will the impact of the maintenance be?
During the maintenance period, it is anticipated that water transfers will decrease by 80 million cubic meters annually.
However, DWS said that analysis conducted in May 2023 indicated that the overall impact on the IVRS will “be minimal”, as reservoirs, including Sterkfontein Dam, are at relatively healthy reserve levels.
“Water users in South Africa need not worry about supply disruptions,” the Department assured.
However, Aina said that residential areas relying on the tunnels, such as Mafube, Nketoana, and Dihlabeng, may face water restrictions, reduced pressure, and shorter availability periods.
Residents might need to use costlier alternative sources like underground water and bottled water, leading to changes in consumption habits. Severe restrictions could drive people to seek unsafe water sources, raising health concerns.
Additionally, the shutdown may impact agriculture, resulting in reduced productivity, crop failures, and financial losses for farmers, threatening food security and local economies.
However, for the areas that may be significantly impacted, the DWS said that it plans to mitigate any potential water supply issues during the shutdown.
They said that additional water is sourced from the Saulspoort Dam to meet the needs of impacted towns like Bethlehem, Reitz, and Tweeling.
The Department said that since 2021, it has been working with affected municipalities and other interested parties to prepare.
DWS emphasised that it “urges all water users who will be affected by the planned tunnel maintenance to use water sparingly during this period, as a means of managing any unforeseen risks,” and a water restrictions notice will be issued.
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