The waters of Table Mountain – Part 2: The Reservoirs

Jun 12, 2012

Up until the mid 1880s, Cape Town relied on a single Table Mountain stream for its water supply: the Varsche River, a confluence of three smaller streams that drains the northern slopes and the Saddle (the neck linking Devil’s Peak with Table Mountain). The drought of 1880 drove home to the 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 water of the Disa River, a strong perennial stream that drained much of the Table Mountain massif. 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 River.

Work on the Woodhead Reservoir began in 1890. Located on the Back Table – also known as the lower plateau, an extensive and undulating area behind (south of) the tabletop summit of Table Mountain, or upper plateau, and about 300 meters (1000 feet) lower down – the reservoir 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 cable car was strung up in 1893, with its lower terminus above Camps Bay and its upper terminus 650 meters higher on the northern edge of Postern Buttress. From here a small locomotive – carried piecemeal up the mountain – conveyed material to the construction site about two kilometers away. A small town 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.

A second reservoir was promptly built a little 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.

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 increase 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 catchment areas that awaited exploitation. 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 5% of the overall supply. In the 1950s, the Woodhead Tunnel began to cave in and 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 bits and pieces of the upper cable car station, a few concrete floors where the village once stood and a few huts, one of which belongs to the Mountain Club of South Africa and another to the Cape Province Mountain Club. A third hut serves as a museum – the Waterworks Museum – where the old locomotive is on display along with various artefacts used during the construction. The museum and old cable car station makes for interesting asides when hiking in the vicinity.

Experience a fragment of history on Table Mountain by hiking up to the reservoirs from the east or west side of the mountain. It’s about a 2-hour hike and well worth the effort. A few tumbledown masonry walls and the odd piece of rusted ironmongery are all that remain of the little cable station on Postern Buttress. Gone is the bustle of construction – people milling about, the chug and snort of the locomotive; now all is silent and peaceful there, the air redolent with fragrant shrub (Coleonema / Confetti Bush), the elements gnawing away at the ruins.