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Whats Happening To Hartbeespoort Dam?
By Helen Duigan
What's Happening to Hartbeespoort Dam?
Sewage discharges are poisoning most major dams in South Africa, including Hartbeespoort Dam. Eutrophication of the water, caused by high levels of nutrients, ie sewage, promotes the growth of cyanobacteria - blue-green algae.
When large numbers of these algae die and decompose they use up the oxygen in the water, leading to fish and other organisms dying. This "eutrophication" is a natural, slow-aging process for a water body, but human activity, such as releasing large volumes of untreated sewage, greatly speeds up the process.
A dead African buffalo found in a reservoir with a dense bloom of the toxic cyanobacterium at the Loskop Dam. ( © 2013 Nature Education Photo by Jannie Coetzee.)
One very common species of algae produces a potent toxin known as microcystin. This is chemically similar to cobra venom. "The microcystin levels found in some major dams - including Hartbeespoort, Hazelmere, Midmar and the Vaal Dam - are amongst the highest ever measured in the world," says Dr Anthony Turton (University of the Free State). "And nothing is being done in South Africa to remove the toxin."
Instead, the Government appears to under-report the extent of eutrophication. Official reports suggest only 5% of the national water resource is at risk, but a recent study by the CSIR has found that at least two-thirds of South Africa’s largest dams are already eutrophic.
Algae in Roodeplaat Dam
The more eutrophication proceeds, the more the 38 billion cubic metres of water in our dams are likely to become unusable. As one expert noted: "The general public remains largely ignorant of the fact that almost all potable water in South Africa is sourced downstream of dysfunctional sewage plants and treated by a bulk water plant that is not designed for this purpose." BizNews.com
The water crisis in the country thus goes far beyond the current drought. As Turton puts it, "South Africa has polluted its national water resource to such an extent that it now faces a crisis of induced scarcity which could have been avoided".