The plan is to ensure the availability of water for power generation, industrial users and other urban groups until 2030.

Construction of Vaal dam, located on the Vaal river some 56km south of Johannesburg, started during the depression of the early 1930s and the dam was completed in 1938 with a wall height of 54.2m above the lowest foundation and a full supply capacity of 994Mm3.

The dam is a concrete gravity structure with an earthfill section on the right flank. It was built as a joint venture by Rand Water and the Department of Irrigation, now known as the Department of Water Affairs and Forestry.

The dam was subsequently raised in the early 1950s to a height of 60.3m, which increased the capacity to over 2Bm3. A second raising took place in 1985 when the wall was raised by a further 3.05m to 63.4m. The capacity of the dam is currently 2.5Bm3 and a further 663Mm3, or 26%, can be stored temporarily for flood attenuation.