No disruption expected during Lesotho Highlands Water Project tunnel shutdown

The six-month maintenance shutdown of tunnels in the Lesotho Highlands Water Project will not disrupt water supply into SA, as alternative plans have been put in place to feed Rand Water and prevent taps running dry, government says.

The department of water & sanitation held a briefing on Friday to outline plans to curb water disruptions when the tunnels are closed for maintenance between October 2024 and March 2025.

The tunnels, which supply water from Lesotho to SA, including Gauteng, will be closed for routine inspection and maintenance work. 

Director-general Sean Phillips said the Integrated Vaal River System (IVRS) would not lack water during the shutdown as backup supply was available from the Sterkfontein Dam.

“The analysis indicated the impact of the outage on the overall IVRS will be insignificant, considering dams in the IVRS such as the Sterkfontein Dam and others are relatively full. This means the closure of the tunnel for maintenance will not result in any disruption of water supply to Rand Water, and to municipalities in Gauteng and other provinces which are customers of Rand Water,” Phillips said.

The shutdown would also not effect water supply to users along the Liebenbergsvlei River in Free State, which usually receives outflows from the tunnel. Additional water will be supplied from the Saulspoort Dam before the start of the shutdown to ensure towns along the river, including Bethlehem, Reitz and Tweeling, will have sufficient supplies during the shutdown.

“Licence irrigators along the Liebenbergsvlei River and its tributaries will be provided with notices to restrict their abstraction during the shutdown to certain days of the week to make sure water is abstracted from rivers fed by the Saulspoort Dam in a sustainable way during the tunnel closure.”

However, the shutdown will result in a shortfall of 80-million cubic metres of water in the Integrated Vaal River System from the 780-million cubic metres transferred per year.

Water transfers will increase after the shutdown to recover the shortfall, Phillips said.

Should the maintenance project exceed the projected six months, the Sterkfontein Dam would continue to be used to supply the Integrated Vaal River System.

Phillips said: “This is a construction project and all construction projects have a risk of going overtime. There are unknown events that can happen, such as unforeseen things found on site until starting with construction, and labour issues.

“According to the department’s assessment, there shouldn’t be any need to release water from the Sterkfontein Dam to go into the systems, but we have it as a reserve supply if unforeseen risks arise.”

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