History of the Vaal dam

During the outbreak of two World Wars, the Witwatersrand experienced significant secondary industrialization, leading to a rapid population growth. This surge in population created an unprecedented demand for water. Between 1915-16 and 1921-22, the number of industrial establishments in and around Johannesburg more than doubled from 862 to 1760. Despite Johannesburg not being built on a large river like many other major cities, the Rand Water Board sought a solution and constructed the Vaal Barrage on the nearby Vaal River in the early 1920s. However, it soon became apparent that this infrastructure was insufficient to meet the growing water needs of the region.

In the early 1930s, the Rand Water Board reached the limits of its water abstraction rights, coinciding with the government’s plans to build a dam at Christiana to supply water for the Vaalhartz Irrigation Scheme. After careful deliberation, it was decided to construct a dam at the confluence of the Wilge and Vaal rivers, approximately 56 km south of Johannesburg near Vereeniging. This dam was envisioned as a mass gravity concrete structure, measuring 518.6 m long with a height of 31.14 m above the mean river bed level. Additionally, an earth embankment, 1,890 m long, was built on the Transvaal (now Gauteng) side or right bank of the river.

To bring this project to fruition, the Rand Water Board entered into a partnership with the South African government. The agreement involved securing 315 million liters per day from the Vaalbank Dam (as it was then known) and contributing R3.3 million towards the total cost of R2.3 million. Subsequently, the Vaal River Development Scheme Act was passed in 1934.

A crucial aspect of the dam’s construction was the relief of unemployment, particularly among the white population, during the Great Depression. In response to the Department of Labour’s request on March 31, 1933, public works were expedited to employ more white laborers for the dam’s construction, along with the Vaalhartz Irrigation Scheme and the Loskop Irrigation Scheme. The government’s primary interest in the dam was to provide irrigation to the Hartz River Valley Afrikaner community in the Northern Cape. Almost half of the dam’s capacity, although some evaporated along the way, was dedicated to this idealistic project. Many individuals from the so-called ‘poor whites’ were employed in the scheme. The Director of Irrigation, AD Lewis, noted in his annual report in 1934/35 that the work was carried out by white laborers in line with the policy of employing European labor only. These laborers, aged between 18 and 45 and unmarried, received a wage of two shillings per day, with a bonus of one shilling 6d per day worked.

An interesting aspect was that these bonuses were paid into a Post Office Savings Bank account, which the workers could only access after leaving the job. Payments to dependents could be made through a stop order. Around 800 men worked on the construction of the dam. However, despite efforts, the Department of Labour found it impossible to maintain the white labor force at the required strength in 1935, necessitating the employment of native laborers on certain sections of the project. Lewis attributed this shift to the increased prosperity of the country and the subsequent demand for labor.

In 1938, work on the superstructure of the Vaal Dam was completed, and a superintendent and small staff were appointed for maintenance purposes. On December 13, 1938, the dam overflowed for the first time, showcasing its full supply capacity of 994 million m3. Lewis highlighted in his report for the period 1938/39 that the dam’s usefulness as a regulator of the Vaal River flow had been amply demonstrated. Notably, it improved the reach between the dam and the Vaal-Hartz Weir by increasing the winter minimum flow and reducing the magnitude of floods.

During the construction of the Vaal Dam, a small village named Deneysville was founded in honor of Deneys Reitz, the Minister of Irrigation at the time.