Dam of dreams

by Willie Meyer – from his book “Magaliesberg Kaleidoscope”

Construction of Sophia Dam – the first dam in Hartbeespoort
General Hendrik Schoeman

General Hendrik Schoeman has carved his place in history by his role in the First Anglo Boer War and especially the controversy surrounding his actions during the Second Anglo Boer War. His violent death in May 1901 when a lyddite bomb, which he used as an ashtray, exploded in his house in Pretoria just added to the controversy which was his life.

What is less widely known was his vision for a dam in the Crocodile River as a focal point for agricultural, industrial, and residential development. Right up to the time when the war disrupted life in the Transvaal, he tried to convince the government to invest in such a project.

So strongly did General Schoeman believe in the viability of such an undertaking that he invested £10 000 in building a dam in the Crocodile River near where the railway bridge in Meerhof is today. The dam, which he called Sophia Dam in honour of his wife, was a nine metre high stone and concrete construction built by the engineer Emil Kunst.

Any success Schoeman might have had in his efforts to get the government interested in, either taking over his dam, or building a bigger one, was spoilt by the outbreak of the war. After the war, Schoeman’s son, Johan Hendrik, revived plans for the building of a dam and he put three thousand hectares of farmland under irrigation from the Sophia Dam, proving the viability of such a scheme. In 1905 a Swedish engineer, August Karlson, also recommended to the government to build a dam and the Transvaal Department of Water Affairs seriously investigated the proposition.

The Sophia Dam was washed away in a flood in January 1909, however, and with the establishment of the Union in 1910, all plans for a dam in the Poort were postponed. Pressures both inside and outside Parliament resulted in the passing of a hastily prepared Hartebeestpoort Irrigation Scheme Act in 1914 without any further investigations as recommended earlier. The cost of the project was then estimated at £605 000. Construction was due to begin towards the end of 1915. Once again war intervened and in addition a host of legal and technical difficulties delayed the start of the project.

According to records kept in the Hartbeespoort Snake and Animal Park library, progress was really only made since 1918 when ground was bought, roads diverted, engineers’ plans compiled and the logistic chain designed to supply material to the Poort, via the railway station at Brits by means of cocopans. When work eventually started in 1920 new problems cropped up. The cofferdam (to temporarily dam up the river so that the actual dam wall foundations could be cast) washed away during the first floods in March 1921. The engineer left and most people involved in the project reportedly gave up. After the flood the department employed an engineer, FW Scott, to take over the project. Scott Street in Schoemansville is named after him.

The dam wall was completed in 1923 and in September of that year the road over the wall, which was the new main road between Pretoria and Rustenburg, was completed. According to the SA Irrigation Magazine of 15 June 1924 a small hydro-electro power station was also completed in that year. The dam overflowed for the first time in March 1925. Lighting for the road and the canals were completed in 1930.[1]

Some technical information:

The water is released at the bottom of the wall by two sluices from where it flows down the eastern and western canals. The eastern canal is 78km long and the western one is 58km. Each canal can handle 5,7 cumecs (5 700 litres per second). The eastern canal runs along the rock face and contains a sluice from where the water can be released via a waterfall to feed the river and the “old furrows”. To build the dam, a total of 250 000 bags of cement was needed which was supplied by Pretoria Portland Cement. The cement was transported by train to Brits where it was transferred to the ox and mule drawn cocopans and transported to the Poort. When the dam is full to capacity the water runs over the concrete overflow. In 1970, 10 steel radial crown sluices were placed on top of the overflow. Because of this the water level of the dam increased by 2,44m. The lake’s volume increased from 160 million cubic metres to 205 million cubic metres. The average daily water loss due to evaporation is approximately 165 000 cubic metres.

A copy of the book by Willie Meyer is available at the Kormorant office.

Also see:

The building of the Dam Wall