Province: Free State
Capacity: 2, 616, 900 megalitres
The Sterkfontein Dam, located just outside the town of Harrismith, in the Free State, is part of the Tugela-Vaal Water Project, and located on the Nuwejaarspruit, a tributary of the Wilge River in the upper catchment area of the Vaal River. The dam receives its water via the Tugela-Vaal Project which is a pumped-storage scheme involving the net transfer of up to 630 million m3 of water from KwaZulu-Natal. This is stored in the Sterkfontein Dam and released to the Vaal Dam via the Wilge River when needed. The Sterkfontein Dam is a highly effective reservoir, since it has the depth to store a large amount of water, with very little loss to evaporation. The Vaal Dam lake (reservoir) by comparison has a large surface area and is relatively shallow, which results in a higher rate of evaporation. The Sterkfontein Dam was originally commissioned in 1977 and comprised 69 m high earthfill embankment 2 290 m long with no spillway. It was subsequently raised in 1980 to its current height of 93 m with a crest length of 3 060 m and a full supply capacity of 2, 616, 900 megalitres. At full supply, it has a surface area of no more than 70 km2. The dam wall contains 17 million m3 of material making it the largest dam wall in South Africa with regard to volume, while the reservoir formed by the dam is the third largest in the country. The dam mainly serves for domestic and industrial use and its hazard potential has been ranked high.