Vaal Dam, Major dam in Deneysville, South Africa

Vaal Dam is a concrete gravity dam with an earthfill section on its right flank, standing 63.4 metres high on the Vaal River. Its left section is a lower embankment with rectangular openings along the top edge, rising to a central gatehouse; to the right, tall pale concrete piers and spans release white water and mist from the base. The reservoir behind it covers about 320 square kilometres.

Construction of this dam began in the 1930s during an economic downturn and was completed in 1938 as a major infrastructure project. The structure was subsequently heightened twice in later decades to meet growing water demands.

The dam's island, about 5 km long, was used by the apartheid government as a secret meeting place. It now hosts the annual Round the Island yacht race, which entered the Guinness Book of Records as the largest inland yacht race, with 389 craft crossing the finish line. The town of Deneysville is named after Deneys Reitz, the irrigation minister at the time of construction.

The area offers good conditions for swimming, sailing, and fishing, with several clubs and facilities spread along the shoreline. Best access is near Deneysville, and most water activities are enjoyed during warmer months.

In February 1996, the dam successfully managed one of the largest flood events ever recorded at the site, handling an enormous volume of water. This event demonstrated its critical role in protecting surrounding areas from extreme weather.