The Government of the Kingdom of Lesotho launched the second phase of the Highlands Water Project (LHWP). In the second phase, the government plans to build a concrete rockfill dam with a 165m wall. The Polihali Dam will be built downstream of the confluence of the Orange-Senqu and Khubelu Rivers in the Mokhotlong District of Lesotho.
The dam will allow the formation of a reservoir on the Orange and Khubelu Rivers over an area of 5,053 hectares, with a total storage capacity of 2,325 million m³. It will be supported by a saddle dam, which is an auxiliary reservoir built to confine the reservoir created by a primary dam, either to allow for higher water elevation and storage or to limit the extent of the reservoir in order to increase its yield.
Highlands Water Project (LHWP)
Highlands Water Project (LHWP) is a bi-national project divided into several phases. It was established by the 1986 treaty between the governments of the Kingdom of Lesotho and South Africa.
The project will involve raising a low point on the margin of the reservoir to prevent water from bypassing the Polihali dam. This saddle dam will have a height of 45m, a crest length of 603 m and a crest width of 6.5m.
Part of the water from the Polihali Dam will be transferred to the Katse Dam in South Africa via a tunnel. With its 185 m height and 710m width, the Katse Dam is currently supplied through a tunnel that connects it to the Mohale Dam. It is used for drinking water supply and agriculture in the Gauteng province of South Africa, in accordance with the 1986 agreements with Lesotho. South Africa, which is co-financing the LHWP with Lesotho, is expected to see the benefits of the project from November 2026.