Aerial photograph of the sluice or silt gates at the bottom of the Pongolapoort Dam Wall, Pongola, Kwa-Zulu Natal, South Africa. The dam is situated 280 km north-east of the port city of Durban. The dam was constructed in 1973 at the eastern end of the narrow gorge separating the Lebombo and Ubombo ranges and was the largest dam in South Africa at the time of its construction. The dam wall is 89 metres high and serves for irrigation purposes.