Abstraction

Abstraction

Water abstraction is a major cause of the problems that Hout Bay’s rivers face. Abstraction by landowners, as well as by the City of Cape Town has had a negative impact on the health of the Disa river specifically.

Riperian landowners have a responsibility to stay within the law of water usage permitted. The relevant authorities may require from anyone claiming entitlement to use river water, to verify – in writing – the lawfulness or extent of that use. For further information you may peruse The Water Act.

A large amount of water is removed by the City, high up in the catchment area of the Hout Bay/Disa River.  The Apostle tunnel takes most of Table Mountain’s southern catchment of perennial water. Ideally this diversion needs to be addressed so that a larger portion of the water directed away from the Hout Bay/Disa River once again enters the river.

Brief history of the diversion of table mountain’s waters from the Disa River

In 1870, it was decided to build a reservior Table Mountain to provide water for the city.

The Woodhead Tunnel was built between 1888 and 1891 and was used to divert the waters of the Disa Gorge to the Slangolie Ravine via a pipe to Oranjezicht.

Also required was a reservoir on top of the mountain. The Woodhead tunnel was constructed between 1887 and 1891 and the subsequent Woodhead dam, constructed between 1890 and 1897, was followed by four others – the Hely-Hutchinson Dam, the Alexandra Dam and the Victoria Dam (built on the original Disa Stream) and finally a fifth dam, the Villiers Dam in 1907. This was built downstream of the Alexandra and Victoria Dams in 1907.

In the 1960s the Woodhead tunnel was replaced with the Apostle tunnel as to provide greater water capacity, diverting even more water away from Hout Bay.

Currently the five dams only supply a small percentage of Cape Town’s water. Most of Cape Town’s water – including Hout Bay’s – comes from Theewaterskloof Dam near Franschhoek.

The floodplain has been reduced by the reduction of perennial water, as well as by structural amendments made to the river by various property owners and the municipality.

The diversion of the Disa River’s headwater has had dire consequences for commercial activities on the river (farming has ceased), as well as on the health of the river system’s ecology.

For full story click here.

Woodhead tunnel (no longer in use)