OVERVIEW OF THE LESOTHO HIGHLANDS WATER PROJECT

The Lesotho Highlands Water Project is one of the largest and most intricate construction projects currently underway in the world. The components included in the project tend to vary from one report to another but in general the total project was originally envisaged to transfer 70 m³/s from the upper portions of the Lesotho Highlands into the Vaal River basin. The scheme was designed in phases, with each phase providing additional transfer capacity to the previous phase with the ultimate transfer of 70 m³/s only being achieved on completion of the final phase.

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Although several configurations have been investigated, the latest generally accepted proposal is for a scheme comprising up to 6 different phases, of which only the first two (phases 1a and 1b) have been approved to date (April 1998).  The most generally accepted components are as follows:

• the 185 m high Katse Dam;
• the intake structure capable of handling 70 m³/s ;
• the 45 km long transfer tunnel from Katse reservoir to the Muela reservoir
• the Muela Dam and hydro-power station;
• the 37 km long delivery tunnel from the Muela reservoir to the Vaal River basin.

• the 145 m high Mohale Dam;
• the 32 km long transfer tunnel from the Mohale reservoir to upstream of Katse Dam;
• the 15 m high Matsoku Diversion Weir;
• the 5.7 km long transfer tunnel from the Matsoku Weir to Katse Dam.

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Phase 2

• the 155 m high Mashai Dam;
• the 19 km tunnel/pumping main from the Mashai reservoir to upstream of Katse Dam;
• the second 45 km long transfer tunnel from Katse reservoir to the Muela reservoir;
• the upgrading of the Muela hydro-power plant;
• the second 37 km long delivery tunnel from the Muela reservoir to the Vaal River basin.

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Phase 3

• the 158 m high Tsoelike Dam;
• the 4.3 km long 3 m diameter transfer tunnel /pumping main from Tsoelike reservoir to upstream of the Mashai reservoir.

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• the 120 m high Ntoahae Dam;
• the 4 km long 3 m diameter tunnel/pumping main from the Ntoahae reservoir to upstream of Tsoelike Dam.

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• the 120 m high Malatsi Dam;
• the 4 km long tunnel/pumping main from the Malatsi reservoir to upstream of the Ntoahae Dam.

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IMPORTANT NOTE :-

It must be stressed that the above mentioned configuration is only one of many possibilities proposed for the LHWP.  The current policy on developments in Lesotho involves only Phase 1 (i.e. Phases 1a and 1b).  No decision regarding further development has yet been made (April 1998).  For further information please refer to LHWP : Statistics.   Alternatively, the DWAF Home Page also has a section on the LHWP which provides the latest information on the project.