High Quality Content by WIKIPEDIA articles! The Vaal Dam in South Africa was constructed in 1938 and lies 77 km south of OR Tambo International Airport Formerly Jan Smuts Airport, then renamed Johannesburg International Airport in 1994, before being renamed yet again on 27th October 2006 as ORT. The lake behind the dam wall has a surface area of about 320 square kilometres (120 sq mi) and is 47 meters deep. The Vaal Dam lies on the Vaal River, which is one of South Africa`s strongest-flowing rivers. It has over 800 kilometres (500 mi) of shoreline and is South Africa`s second biggest dam by area and the third largest by volume.