The Steenbras dams seem surprisingly full, even though we are experiencing a drought, but there are a number of factors to take into consideration.
As Cape Town experiences the worst drought in 100 years, the Steenbras dams still seem surprisingly full. We explain why below.
Upper Steenbras is not only used for water storage. It forms the upper reservoir for the City’s Steenbras pumped storage scheme, which generates extra electricity during peak demand.
During peak demand, water from Upper Steenbras is channeled through the turbine generator to create electricity. Water collected in Lower Steenbras is pumped to the upper dam at night, using low-cost surplus power.
Upper Steenbras is also linked by canal and pipeline, to Rockview Dam, the upper reservoir of the Palmiet pumped storage scheme operated by Eskom and the Department of Water and Sanitation. It receives transfers from the Palmiet River via this scheme.
Together, both Steenbras dams (Upper and Lower) make up 7.4% of Cape Town’s supply capacity (they’re relatively small compared to the likes of Theewaterskloof and Voelvlei. The are also narrow, deep dams which suffer less from evaporation, so it makes sense to use water from shallower dams sooner.