Dams of Table Mountain – Part 2/3

Jul 28, 2023

Up until the mid-1880s, before the dams were built, Cape Town relied on a single Table Mountain stream for its water supply: the Varsche River, a confluence of three smaller streams that drained the northern slopes and the Saddle (the neck linking Devil’s Peak with Table Mountain).

Why were the dams built?

A succession of droughts in the early 1880s impressed upon town planners the stark reality that the city needed more water, and fast. John Gamble, incumbent Colonial Hydraulic Engineer, revived an earlier idea that a tunnel be driven through the Twelve Apostles to capture the waters of the Disa Stream, a strong perennial stream that drained a large chunk of the Table Mountain massif.

The 12 Apostles Peaks Table Mountain – Pipeline

Work on the 700-meter tunnel started in 1887, as did the construction of a pipeline several kilometres long, stretching from the tunnel exit in Slangolie Ravine on the Twelve Apostles to the Molteno Reservoir in the city center. But even before the tunnel’s completion, it became clear that more should be done to secure a steady supply of water. That’s when they decided to dam the Disa.

The Woodhead Dam Table Mountain – Disa Gorge

Work on the Woodhead Dam began in 1893. Located on the Back Table – an extensive area behind the tabletop summit and about 300 meters (1000 feet) lower – the dam spanned the Disa Gorge along its middle stretches. The construction was a major undertaking: long lines of porters toiled up Kasteelspoort, a ravine on the Twelve Apostles that offered easy access, laden with building material.

To assist in the task, a small open-skip, steam-driven cableway was strung up, its lower terminus in Camps Bay and its upper terminus 650 meters higher on the northern edge of Postern Buttress. From there, mule-drawn trolleys (and later a small locomotive) conveyed material to the construction site about a kilometer away.

A hamlet sprung up on the summit, complete with its own bank, post office and shop. The dam wall, constructed from sandstone blocks quarried on the mountain, measured 252 meters across and 44 meters high, with a base thickness of 19 meters tapering to 3 meters at the top. But in 1898, only a year after its completion, it became apparent that the city’s water demand had outstripped supply – again.

The Hely-Hutchinson Dam Table Mountain Dams – The Back Table

A second dam was promptly built upstream from the first, completed in 1904. Named Hely-Hutchinson, its masonry wall measured 528 meters, while its water surface covered an area of 16 hectares. During all this time, the Wynberg municipality (a suburb of Cape Town and a separate municipality) had been labouring away at its own reservoirs on the mountain, three in total (Victoria, Alexandra and De Villiers), located further south on the Back Table, tapping a tributary of the Disa River.

The Steenbras Dam – a solution for Cape Town water

But Cape Town’s water woes did not end there. In 1905, the city became aware that demand yet again threatened to outstrip supply. After considering several alternatives and ideas, the city decided that Table Mountain’s water was utilized to the hilt and that more dam-building would not solve the problem.

Instead, it undertook to obtain water from the Steenbras Dam, situated about 80 kilometers outside Cape Town. This set the tone for future efforts to boost Cape Town’s water supply. The chain of mountain ranges northeast of Cape Town stretching from Somerset West in the south to Ceres in the north offered extensive catchments that awaited exploitation.

Are the Table Mountain Dams still in use?

Currently, Cape Town has six supply dams, the most recent addition being the Berg River Dam, opened in March 2009 and boosting the city’s water supply by a whopping 20%. Table Mountain’s reservoirs are still in use, contributing around 1% of the overall supply. In the 1950s, a succession of rockfalls in Slangolie Ravine compelled the Waterworks Department to abandon the Woodhead Tunnel. A new tunnel was built a few hundred meters to the north, exiting on Woody Buttress on the Twelve Apostles. This enabled the Woodhead and Hely-Hutchinson reservoirs to remain in use.

Nowadays, all that remain of the construction site are the masonry walls of the cableway’s upper terminus, a few concrete floors where sheds and cottages once stood and a few cabins, one belonging to the Mountain Club of South Africa and another to the Cape Province Mountain Club. Another building serves as the Waterworks Museum, where the old locomotive enjoys pride of place alongside various artifacts used during the construction. The museum and old cableway terminus makes for interesting asides when hiking Kasteelspoort, Woody Ravine and even Skeleton Gorge.

Most Table Mountain hikes can be adjusted to include one or more scenic or historic sights, depending on your interests and fitness.

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