Emmarentia Dam, Water reservoir in Emmarentia, Johannesburg, South Africa.

Emmarentia Dam is a stone-and-earth dam on the Westdene Spruit in Emmarentia, Johannesburg, about 400 metres long with a maximum depth of 6.7 metres and a water surface of 8.8 hectares. The Johannesburg Botanical Garden lies on its western shore; the eastern shore, south of the dam wall, holds the Emmarentia Sailing Club, Normalair Underwater Club and Dabulamanzi Canoe Club, and the 1st Victory View Sea Scout Group boathouse stands on the main dam east of the gardens.

Lourens Geldenhuys bought the Braamfontein farm land in 1886 hoping the Confidence Reef would reach it; it did not. After the Second Boer War his son Louw, a Krugersdorp Commando veteran, hired landless and unemployed Boer veterans to build a stone and earth dam over the Westdene Spruit at a cost of £12,000, naming it after his wife Emmarentia Botha. A hundred workers were settled on 14 irrigated smallholdings of 145 morgens, growing fruit and vegetables for rent of a third of the produce profits.

The dam is named after Emmarentia Botha, wife of Louw Geldenhuys, and the suburb that grew beside it took her name in 1937. On the eastern shore south of the dam wall stand the Emmarentia Sailing Club, the Normalair Underwater Club and the Dabulamanzi Canoe Club, while the 1st Victory View Sea Scout Group keeps its boathouse on the main dam east of the gardens.

Several entry points provide access to the water for activities like canoeing and windsurfing, with a café nearby for refreshments and snacks. Visiting during daylight hours is most comfortable, and wearing proper footwear makes exploring the surrounding pathways more enjoyable.

The main dam wall was rebuilt between April 2015 and May 2016 for R25 million, the first upgrade since 1988; the work strengthened flood protection for homes downstream. Residents asked for a clean-up while the dam was drained. The spillway releases water back into the Westdene Spruit, feeding a small lower dam near John McKenzie Drive.