Lesotho Highlands Water Project
The Lesotho Highlands Water Project is an ongoing water supply project with a hydropower component, developed in partnership between the governments of Lesotho and South Africa. It comprises a system of several large dams and tunnels throughout Lesotho and South Africa. In Lesotho, it involves the rivers Malibamatso, Matsoku, Senqunyane and Senqu. In South Africa, it involves the Vaal River. It is Africa's largest water transfer scheme.
The purpose of the project is to provide Lesotho with a source of income in exchange for the provision of water to the central Gauteng province where the majority of industrial and mining activity occurs in South Africa, as well as to generate hydroelectric power for Lesotho (currently almost 100% of Lesotho's requirements).
Efforts to create a dam in the location were spearheaded by then British High Commissioner Sir Evelyn Baring in the 1950s. After a complete feasibility study was conducted between August 1983 and August 1986 (German-British Lahmeyer MacDonald Consortium was appointed for this task), the project eventually began to realize.
The project has also been alleged to have had negative social and environmental effects. While compensation was provided in kind and paid to the few hundred households affected by the dams, there is criticism that it was insufficient. It was not intended to address the water supply problems in Lesotho, but by paying royalties to the Lesotho Government for development purposes benefits have reached much of the population.
In recent years, water from the scheme has been discharged into the Mohokare (Caledon) river to provide water to Maseru in times of critical shortages. The new dams have filled as anticipated and discharge of water from the dams into the downstream rivers continues in a scheme devised to preserve ecological balances. This discharged water flows to the Senqu (Orange) and while preserving the ecological status quo benefits only those communities along the rivers.
The project has had an important impact on Lesotho's infrastructure, as hundreds of kilometers of engineered paved roads were built in order to improve access to the different construction sites, and, together with engineered unpaved 'feeder' roads around the dams, continue to provide much improved communication for many villages in the mountainous interior.
Since its inception the project has been dogged by corruption which has resulted in a number of court cases involving both individuals and multinational corporations.
Below is an overview of the main features of the first three phases of the project.
|Phase IA||Phase IB||Phase II||Phase III|
|Name||Katse Dam||Mohale Dam||Mashai Dam||Tsoelike Dam|
|Dam height (m)||155||153||182||155|
|Power generation* (MW)
|Water transfer capacity* (m³/s)||16.9||10.1||28.0||8.6|
* The values are estimates based on the feasibility study, and may differ from the current or eventual values, respectively.
Phase IA: Katse Dam
This phase of the project was completed 1998. It consisted mainly of the construction of:
- The Katse dam, a concrete arch dam, across the Malibamatso River.
- The Matsoku weir and tunnel, to collect an input from the Matsoku River to the east.
- A 48.2 km long transfer tunnel between the Katse reservoir and the Muela hydroelectric power station, in northern Lesotho.
- A 110 MW hydropower plant at Muela with an embankment dam with central impermeable core.
- A delivery tunnel which draws water from Muela and carries it underneath the Caledon River at the Lesotho/South Africa border and underneath the Little Caledon River at Clarens to discharge it into the As River from where it flows into the Wilge River and eventually into the Vaal River.
Although the Katse dam has power generation capability for local use, the primary purpose is as the storage basin for Phase IA and provide discharge into the transfer tunnel.
Phase IB: Mohale Dam
This phase of the project was completed 2002. It consisted mainly of the construction of:
- The Mohale dam, a very large rockfill dam, located on the Senqunyane River.
- A transfer tunnel between Mohale and the Katse reservoir.
The system is interconnected in such a way that water may be transferred in either direction for storage in Mohale or ultimate transfer to South Africa through the Katse reservoir.
As initially conceived, three further dams were proposed further downstream after the Malibamatso joins the Senqu river, at Mashai, Tsoelike, and Ntoahae.
In 2007, further studies resulted in a modification, proposing instead a dam on the Senqu upstream from the confluence with the Malibamatso. This is currently the preferred extension of the scheme, although construction has not yet begun (as of December 2007).
- Lesotho Highlands Development Authority
- Trans Caledon Tunnel Authority picture gallery
- Lesotho corruption trial relating to project
- Lesotho Highlands Further Phases Feasibility Study