Why is water currently flowing out of the Vaal Dam in South Africa not banked in Lesotho’s half-empty dams? Gauteng’s water security is being put at risk by failure to come to an agreement between the two countries. And that risk will continue to increase along with population growth and water consumption between now and 2026 when Polihali Dam in Lesotho is due to be completed.
Recently the Bloemhof Dam, downstream of the already spilling Vaal Dam, also started to spill. There are no big dams to catch this water further down on the Vaal River, nor further downstream after it joins the Orange River. All the water that goes over the wall of the Vaal Dam ends up in the Atlantic Ocean at Alexander Bay.
While the major dams on the Vaal/Orange River system in South Africa are all full and spilling, this is not the case for the large dams of the Lesotho Highlands Water Project (LHWP). The Katse and Mohale Dams, built to support the Vaal Dam and financed by South Africa, together stand at only 57% – a shortfall of 1020-million cubic meters. This is more empty space than two full Theewaterskloof Dams put together.
Yet water is currently released from the Katse and Mohale Dams at a rate of 38 m3 per second. That is 3.3 million m3/day – more than six times the present daily use of Cape Town. Instead of storing the water at high elevation and at conditions with low evaporation (see article “Vaal Dam spilling: Drought, what drought?” ) this released water ends up in the sea. Why? Because Lesotho is using the water to generate power.
While the transfer of water from Lesotho to the Vaal Dam was always the primary purpose of the LHWP, the 1986 treaty gave Lesotho the opportunity to build a hydropower station utilising the water released to South Africa. While modest in relation to the generating capacity of South Africa, this station currently generates a substantial portion of Lesotho’s electricity needs. Their remaining requirements come from South Africa. However, the operating rules favour generating of Lesotho’s hydropower to the detriment of water security for the economic heartland of South Africa – the cost of which greatly outweighs its benefit.
In the negotiations preceding the agreement on the Polihali Dam as the second phase of the LHWP, the issue of the sub-optimality of the operating rules was addressed. In 2011 the countries agreed to jointly investigate these rules from a total system perspective with the view to ensure optimality of water supply to South Africa whilst considering Lesotho’s energy security. It was envisaged that these investigations would include compensatory measures to Lesotho, such as providing additional power from South Africa. With common-place load-shedding at the time, Lesotho may have felt nervous about assurances of electricity from South Africa. However, conditions have substantially ameliorated since then.
Yet after seven years since 2011 little progress has been made; modalities for improving the operation of the LHWP are not yet in place – therefore the wastage of water as so evident currently. This water may prove to be critical for Gauteng in the years between now and 2026 when Polihali Dam becomes operational. Already the water supply system is extremely tight; only recently could curtailments be lifted, and the risk of future shortages will increase as water requirements increase.
A golden opportunity exists for Lesotho and South Africa, already inextricably linked socially and economically, to demonstrate their willingness to deepen cooperation by urgently addressing the wasteful operation of the LHWP – not only for the sake of Gauteng’s water security but also for the wider regional benefit. DM
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