Zandvlei is sick and we are to blame

Blue letter

Trevor Dix, Marina da Gama

Zandvlei water is putrid. There is no way the City of Cape Town can just fob this off. Just read Zandvlei nature reserve reports to Marina property owners during 2019 and 2020: there have been so many sewage spills I have lost count.

About five or six years ago, the weeds were a problem to boat people and had to be cut to prevent them from seeding. And then the flamingos … And what did we do? We exterminated hundreds. Why? Crazy thinking.

Today, as I write, there are none. Only two lonely geese. There is no food and the water is putrid.

Back then we also had shoals of baby fish along the coast. Now there are none.

It’s a disgrace that us humans have been allowed to destroy the environment like this. Nature would never allow this to happen.

With regard to the statement that Zandvlei has also received faecal waste from birds and other animals using the wetland, what absolute nonsense! These creatures were here long before us humans, and they only helped the environment. How can mayoral committee member for spatial planning and environment make such a statement?

Officials should get off their butts and go and look at the two canals that flow under Military Road into the Sand River and then into Zandvlei. Everything is thrown into these canals as they flow through Retreat and Steenberg, and stuff also comes from Kirstenhof and Dreyersdal.

Lorry loads are trapped but a lot gets through. Also, a lot of plastic from road drainage arrives in Zandvlei. We have to educate people. I am always positive, and just maybe it’s not too late to sort this out.

• Mayoral committee member for water and waste Xanthea Limberg responds: The City is well aware of the symbiotic and environmental importance of the Zandvlei and the marine environment and manages the Zandvlei mouth and the vlei in accordance with accepted best management protocol and practices.

Please note that water samples are only taken every 30 days, and are only representative of water quality at this exact point in time, and at that exact sample point. Results are not intended to be seen as representative of constant water quality throughout the vlei. Water quality in an urban environment typically fluctuates from day to day and from point to point, and deteriorates especially during rainfall which washes pollution from the urban surface into drainage systems and eventually rivers and oceans. Monthly sampling is adequate in order to monitor trends broadly at catchment level, but it will not be effective at recording fluctuations between testing periods. More frequent sampling at the many sample sites in the inland monitoring network is not possible due to cost and laboratory capacity constraints.

The respective City line departments also collectively undertake necessary and appropriate mitigation measures in managing the water quality, as soon as a sewage overflow is detected and reported. Please note that the majority of sewer spills are not caused by structural factors or negligence, but by dumping into the sewer line, illegal flushing of rags, wet wipes, and feminine hygiene products, as well as ingress of cooking oil/fat into the sewer system (which is also illegal). The City is working to raise awareness around these issues so that resources that could be used for increased proactive maintenance are not being redirected to mitigate the effects of by-law contraventions.

• Mayoral committee member for spatial planning and environment Marian Nieuwoudt responds: We can confirm that there has been no extermination of flamingos at Zandvlei. The presence of flamingos is dependent on water levels and the absence of pond weed. Flamingos are nomadic and move around southern Africa to water bodies that match their habitat requirements. During the recent drought years, Zandvlei had high levels of salinity, which suppressed pond weed growth and encouraged flamingos at the time. The flamingos, however, are still present in the vlei. They roost in the northern sections and are often spotted feeding off Park Island.

The mouth management of Zandvlei is an important tool to maintain salinity in the water body, as well as allowing for the ingress of juvenile fish from the ocean. Zandvlei is a vital nursery for fish along the False Bay coastline and the opening of the estuary mouth at spring high is an important management tool to allow for these fish to persist in an altered system.

It should also be noted that all natural ecosystems receive faecal waste from birds and other organisms that live in them. This organic waste is often part of the natural enrichment of ecosystems and the basis of food chains. Such faecal waste can, in certain circumstances, also influence water quality results.