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Water Hyacinth at Hartbeespoortdam

Harties hyacinth, Wastewater treatment works and packaged plants

" Mum takes care of it "

When nature is in balance, then all life on earth is contented. It will balance itself, and anyone who thinks they can change nature, are arrogantly naïve. Should a man-made problem occur, our global Mum will take care of it, and often this action is not acceptable to us. So we try and solve it with another human reaction, and Mum retaliates again, each time the problem gets worse. The water hyacinth infested Hartbeespoort Dam is a fine example.

Hartebeespoort Dam with invasive hyacinth

Hartbeespoort Dam


Professor Turton says

When Anthony Turton, a renowned water specialist, publishes a document, it adds increased weight to the topic, and the longstanding hyacinth problems at Hartbeespoort Dam is his latest publication.

Professor Turton, who has developed a reputation for telling it like it is, has not always been in the authorities’ good books. He does not do their bidding, and feels there cannot be any politics in water. If water is clean, then its right.  Add a little contamination, its no longer clean, and our water cadres don’t like to acknowledge this.

Hartbeespoort Dam has been getting some serious attention of late, as the hyacinth growth has never been resolved. I was at a public meeting way back in mid 2005, held at the Pecan Estate.  Department of Water Affairs (DWAF) officials offered their explanation what the problem was and what should be done about it. It must be presumed that there has been no progress, since the hyacinth has developed into a major problem, even to a point where people are inconveniently trapped in their boats.

Further reports now indicate that the hyacinth has been detected in Loskop Dam near Middelburg – Mpumalanga. And so, we are not resolving these issues – they are growing.

Dr Turton mentions that the water has excess nutrients, which come from the 10 municipal wastewater treatment plants upstream from Harties Dam.  There are a number of package plants in the area, and DWAF proportion some of the blame on these installations.  Many of these on-site systems and WWTW are badly run, overloaded, and subject to the negative affects of load-shedding.

Package plants at Hartbeespoort DamDWAF Document


Excessive Nutrients - Nitrates and Phosphates

Sewage contains high levels of nitrates and phosphates - both these nutrients are found naturally in untreated sewage. Any attempts in removing these components, prior to release into the environment are thwarted by lack of care, incompetence and even sabotage. Back in the old days of apartheid, a municipal manager who allowed more that a litre of this water to reach the environment, would have endured a disciplinary hearing.

    We now have the democratic freedom to discharge what we want.   

The proposed Harties solution vary from herbicidal sprays, physical removal, importing worms, and even farming weed, all of which have been tried and received no lasting results. It is believed that the property homeowners are willing to spend obscene fistfuls of $ on a solution, but not a cent on “trials”. To them, the hyacinth plants are a nuisance, and “we don’t like it”.

Many observers claim the hyacinth is an alien invasion - absolute rubbish.  Aliens never developed it, or brought it to this planet. Mother invented it to care for her world, and that is why it's here. Get used to it!

Fish Kill - when oxygen is depleted in water

Fish kill

Fish kill and bulking

Another report claims great success where bugs eat away at the core of the plants, and they die, sinking to the bottom of the dam. Great stuff, but decomposing vegetation absorbs oxygen and fish could die. This is aptly termed “Fish Kill”. The water then needs further human intervention, and artificial aeration methods ,(like fountains and fine bubble diffusers) are then adopted. Futher-more, decomposing vegetation can create gasses to form underneath, and the rotten vegetation start to float to the surface. This is called “bulking”.  Once on the surface, it soon dries out, leaving a tough crust which is unhealthy, unsightly, and a magnet for insects. Then, these floating islands create a platform for more growth, and it is not likely to be bug eating hyacinth, as seen below.

Bulking in clarifiersBulking in clarifiers promotes rapid plant growth - as seen here.


Blue-green algae and harmful algal blooms

We don’t seem to be getting on top of this issue, and perhaps we should be looking inside the box. The elephant in the room is the excessive nutrients. Remove the nutrients, and the problem resolves itself. However, removing the hyacinth, does not do this, but makes matters worse. Without hyacinth stopping light, sun’s rays reaches the nutrient rich water, and blue-green algae develop quickly into harmful algal blooms. This algae produces a toxic environment, which, according to Turton’s report, is considered carcinogenic.  It also negatively affects fish-life and is harmful to humans. At least the hyacinth does not poison the water, even though it is neither aesthetically pleasing, nor great smelling.

Blaming the hyacinth is the easiest option whilst we ignore the nitrates and phosphates.  Remove these, and nature will return the water of this dam to full clarity. Why is this so difficult to understand? And why are nutrients always seen as a problem? If handled differently, this can be turned around resulting in lemonade.


Nutrients encourage plant growth, and if plants were grown upstream, then nutrient levels will drop in the dam. Consider a complete hydroponics farm is developed using water diverted from the river, and excess water would be released back into the water course, and very little water would be lost. Agricultural produce, like lettuce (not to be confused with water lettuce), cabbage, carrots etc could be grown, perhaps on an industrial / commercial scale, could be possible, without being too labour intensive. We all know hyacinth will do well, and reduce the problem in the dam, and, they have proven to thrive very well without any human effort. If farming hyacinth is a solution, do it before the dam.

Should the landowners be encouraged to support such an program, this could be self-sustaining, profitable and beneficial to the area.  Read about innovative organic farming with nitrates


Another novel idea to resolving this problem – just fix the damn wastewater treatment works.

Packaged Plants

And finally, it is known that there are a number of packaged plants (DWAF mentions this) on estates, and one wonders what contribution they add to the nutrient problem. When were they last checked for nitrates, in particular? My guess is they haven’t, and the body corporates / management are delighted at pointing fingers at things that are out of their vision of responsibility.

Perhaps the notion of "going green" is not such a desired outcome.


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