Katse Dam - Highlands Water project - phase 1a

Name of Project:

Katse Dam - Highlands Water project - phase 1a


Lesotho Highlands Development Authority

Construction period:
February 1991 - May 1997

The Katse dam is part of the Lesotho Highlands Water Project (LHWP), one of the most ambitious multipurpose water schemes. The main purpose of the project is to deliver approximately 70 m³/s of high-quality water to the Vaal dam reservoir. The Gauteng region includes the cities of Johannesburg and Pretoria, and has the highest concentration of mining and industrial activities in South Africa.

The Katse is Africa’s highest dam. It is a 185 m high double-curvature concrete arch dam with a total volume of 2.32 million m³. Located on the Malibamats'o river, 2.5 km before the confluence with the Bokong river, its reservoir has a capacity of 1,950 million m³ of water. The dam has a crest length of 710 m and a width of 60 m at the base and 9 m at the crest.

The spillway is built into the dam crest and can release up to 6,250 m³/s.

The river diversion was achieved with two tunnels, 643 m and 598 m long respectively, with a diameter of 7.5 m, and a rollcrete cofferdam 35 m high, 240 m long, with a volume of 90,000 m³.

The 2.5 million m³ of aggregates, taken from a nearby quarry, were transported from the primary and secondary crushing plants to the tertiary crushing plant on a continuous 2.4 km conveyor belt, which crossed the valley and passed through a 1.4 km tunnel built ad hoc. All the materials were delivered to the Katse dam site on the 150 km access road, via a mountain pass at an altitude of 3,090 m.

Earth excavation: 700,000 m3
Rock excavation: 1,400,000 m3
Underground excavation: 135,000 m3
Rollcrete: 90,000 m3
Concrete: 2,500,000 m3
Underground concrete: 47,000 m3
Dam grouting: 5,000 m3


Last update: 18/09/2013