Overview of the Lesotho Highlands Water Project (LHWP)                        <<..back [continuation]                                                                                                          

The bi-national, Lesotho Highlands Water Project (LHWP), between the Kingdom of Lesotho (KOL) and the Republic of South Africa (RSA), is one of the most comprehensive engineering projects of its kind in the world, aimed at harnessing the water resources of the highlands of Lesotho to the mutual advantage of South Africa and Lesotho. The whole concept of the LHWP can be traced as far back as around the 1930s^§, in which the idea of capturing the Lesotho high summer rainfalls by dams and transferring to parts of RSA, enthused South Africa.

Preliminary Studies

The initial survey of the water potential of Lesotho was first introduced by the then British High Commissioner to Lesotho Sir Evelyn Baring around the 1950s. Ninham Shand of South Africa was appointed as consulting engineer to study the potential of harnessing the water of the Maluti Mountains for economic benefit of the Basotho people.

A study of the Oxbow project was undertaken for the Government of Lesotho from 1967 to 1968 (Ninham Shand and Partners, 1968). That study envisaged storage reservoirs at Oxbow and Pelaneng on the Malibamats'o River with tunnels northward to convey water to South Africa. In 1971 the Government of Lesotho (GOL) commissioned a further study (Binnie & Partners, 1971) which concluded that a 94m high Pelaneng dam could be constructed to divert a continuous supply of 8m³/s to South Africa.

In 1974 the Republic of South Africa (RSA) appointed Henry Olivier and Associates to carry out studies in connection with water and power projects in the neighbouring countries. In a report submitted to the RSA in 1977 (Henry Olivier and Associates, 1977), ten alternative layouts for diversion of water from Lesotho to the Vaal basin and for possible hydroelectric projects associated with such projects were described.

Joint Preliminary Feasibility Study

A joint preliminary feasibility study of the project with each government appointing its own consultants to assist in the study was carried out in 1978. A preliminary Feasibility report (Olivier, Binnie, 1979) concluded that a constant flow of some 35m³/s could be transferred to South Africa using a phased construction of five reservoirs at Oxbow, Pelaneng, Soai, Polihali and Taung on the Malibamats'o and Senqu (Orange) rivers and approximately 102km of tunnel to transfer water to South Africa. The generation of hydroelectric power in Lesotho was an integral part of the project proposal.

Joint Detailed Feasibility Study

The detailed feasibility studies to suit the requirements of the two governments were carried out from August 1983 to December 1985 by Lahmeyer MacDonald Consortium (comprising Lahmeyer International of Germany and Sir Malcolm Macdonald of U.K.) for GOL and Olivier Shand Consortium (comprising Henry Olivier and Ninham Shand Inc.) for RSA. The government of Lesotho's interests were looked after by the LHWP Unit (LHDA's and JPTC-GOL's predecessor) who were assisted by TAMS Pty. (Ltd.) of the U.S.A. in the technical review field. The LHWP unit and TAMS together formed the Study Supervisor for GOL on the Feasibility Study from 1983 to 1986.

The main objectives of the feasibility study were: -

• Selection of the optimal scheme layout acceptable to both governments;

• Demonstrating that the project would be technically, socially, legally, environmentally, economically and financially viable;

• Carrying out of studies, designs and costing which would be used for purposes of preparation of tender designs and associated investigations.

Detailed reports issued under the detailed feasibility studies were in volumes as follows:

1. Hydrology Studies

2. Geo-technical and construction materials studies

3. Environmental and social impact in Lesotho 

4. Topographic surveys and mapping

5. Management and Manpower Studies 

6. Legal Studies in Lesotho

7. Infrastructure

8. Design Studies

9. Project Cost Studies

10. Economic and Financial Appraisal

The Feasibility study established the economic viability of the project to deliver about 70m³/s of water from the highlands of Lesotho to the Vaal River system by the year 2020. The project was to be developed in a number of phases and the project was found to be the cheapest option compared to other competing schemes in RSA.

Hydroelectric power was to be generated in Lesotho, which offered Lesotho the opportunity for a substantial element of independence in electricity supplies.

The study confirmed that there were no technical, social, environmental, legal, economic or financial considerations, which would invalidate the conclusions that the recommended project would provide considerable benefits for both countries.

The recommended feasibility study Phase 1A project components were as follows:

• Main Dam and appurtenant Works at Katse

• 48 km long Transfer Tunnel from Ha Rafanyane to Sentelina

• Sentelina Head Pond

• Underground Hydropower Plant

• Tlhaka Tail Pond

• Delivery Tunnel

• Infrastructure facilities including access roads, construction camps, construction-power, communication and other services.

An independent 3-member international panel of engineering experts was engaged by Lesotho from January 1984 to February 1986 to review the Feasibility Study work. During this period, the panel made three visits to Lesotho and to the project sites.

LHWP Implementation

The signing of the Lesotho Highlands Water Project Treaty by the Government of Lesotho and of the Republic of South Africa on the 24th October 1986 established the Joint Permanent Technical Commission (JPTC) to represent the two countries in the implementation and operation of the LHWP. This was followed by detailed Engineering studies and services prior to the award of main works, which were scheduled to commence in early 1990. The treaty commits RSA and Lesotho to implementation of Phase 1A and 1B of the project and provides the options for development of additional phases in the future.

The first Phase (1A) of the proposed four phased scheme, comprising a giant dam, at Katse in the central Maluti mountains, 82km transfer and delivery tunnel system reaching to the Ash River across the border in R.S.A, 'Muela hydropower station and associated structures have now been completed. This phase was commissioned in 1998 and an average 17m3/sec of water is now being delivered to R.S.A.

Phase 1B, comprising; Mohale dam, a 145 metres high concrete faced rockfill dam on the Senqunyane river some 40km south-west of Katse; a 32 km long transfer tunnel between Mohale and Katse reservoirs, a 19m high concrete diversion weir on the Matsoku river and a 5.6km long tunnel, are under construction. The Mohale reservoir and Matsoku diversion will add 9.5 and 2.2 m3/sec to the yield of Katse. Completion of these components is scheduled for 2003/4.

Further Phases

The feasibility study layout envisioned the following:

• Phase II: Construction of Mashai dam (estimated to be 170m high) on the Senqu river at Mashai, a pumping plant and water conveyance tunnel to Katse.;

• Phase III: Construction of Tsoelike dam; A dam constructed just below the confluence of the Senqu and Tsoelike rivers some 90km downstream of Mashai dam and;

• Phase IV: Another dam at Ntoahae, 40km downstream of Tsoelike dam on the lower reaches of the Senqu river

Completion of all four phases would provide the 70 cumecs foreseen at feasibility study stage.

The Treaty provides for negotiations to be held between Lesotho and RSA before further phases of the LHWP can be implemented Such negotiations are on-going ,but it is now accepted that there will be a delay before phase 2 can be undertaken.

§ New civil engineer 14^th Sept. 1995, pp. 20 - 29