The drought is affecting the Zandvlei estuary in two major ways: the water quality and quantity as a potential source of water.

The important message here is that Zandvlei is under stress, like all other local wetlands, due to the low water levels from the drought. The nutrients that have accumulated in wetland systems over time can now be expected to be manifested in algae blooms , excessive plant growth and in this case a new weed species coming to the fore. Wetland systems can be expected to manifest water quality issues in response to the stress imposed upon them by years of city runoff, pollutants and the drought conditions. What we are seeing are symptoms of underlying stresses placed upon our wetlands.

Water quality

The condition of the Zandvlei estuary is currently a cause for closer monitoring. It is not as dire as some may suggest, considering what it has to accommodate:
1.         There is a larger than usual amount of stringy algae. This is due to the hot temperatures, and also a nutrient build up because there is not enough flow to flush the system, because of the extreme  drought.   Lower water levels concentrate nutrients already in the system – high temperatures spurn algal growth.
2.         The drought also means that there is a larger build-up of nutrients higher up in the catchment. When rain does come it washes large amounts of nutrients off the catchment into the estuary in one or two events, as opposed to continued rain with small amounts of nutrients over a long period.
3.         The biggest challenge the system currently faces is sediment build up which is impairing the functioning of the estuary as a nursery. The annual maintenance dredging has been redirected to drought emergency measures.
4.         The mouth opening depends on flow into the system to manage the salinity, and the flow has been low due to the extreme drought. The build-up of sand in the mouth of the estuary means that when there is tidal interchange the amount of water exchanged with the sea is limited. In addition, the budget for this is also constrained due to drought emergency measures. The sand bar, coupled with the long drought, means a decrease in sea water exchange and a decrease in flushing of the system. Thus the conditions seem to be set for poor water quality issues in the summer ahead.

The top priority of the ZPAAC currently is to dredge the estuary. While this will have a positive impact on the nutrient balance and hence pond weed growth, the pond weed management is not the main topic under scrutiny. Any help obtaining funds or assistance in getting any amount of dredging done will be welcomed.

Water extraction

There has been reports of water being extracted from the estuary. It is illegal (see below), but people removing water by hand from Zandvlei wouldn’t be a huge ecological disaster; there may be health consequences but this would probably be out of the ambit of the City to resolve.

In terms of the Marina; the first 2m of water is owned by the adjacent property and is not Council property. Thus Council permission is not needed as they are not the land owners. The person however still needs a water use licence from National Government and be registered as a water user.

The Zandvlei water has a high salt content (about half sea water) so it won’t be too good as drinking water.

Below is an extract of the present legislation – it is old and outdated but still in effect. If you witness water extraction, please call the reserve ranger staff (24/7) at 083 499 1717 (please note this is for ENVIRONMENTAL emergencies only).

 

 

6 thoughts on “Zandvlei in the drought

    1. Hi Pierre, yes, it is part of the management plan, but we lack funding. The better long term solution is to rehabilitate the banks to be more natural, and incorporate estuarine habitat. This will improve bird and wildlife as well as improve the water quality, and be able to absorb the fluxes of the estuary, which reduces the erosion. In some places, like for watercraft moorings and where the road near the caravan park is close to the bank, a structural solution will still be used.

      To address the funding we need to be creative and raise funds or allow careful, responsible economic activity – please share your thoughts here: http://zpaac.org.za/2018/01/19/dream-zandvlei-members-wishlist/

  1. Please note that the canals that feed Zandvlei are not all stagnant and that there is positive water flow in these canals all the time constantly adding to the vlei. (from springs and mountain streams).
    What happens downstream when the vlei mouth is closed to starts backing up downstream to the canals.
    We have found tons of plastic in Zandvlei some places waste deep.
    https://www.youtube.com/watch?v=94BFVHja8L8&index=68&list=PLGHpE2bkH3gGqB_hB-o-G-ELJb4O-zqK6

  2. What on earth is the point of the law prohibiting people from removing water from Zandvlei?

    We all know that the river mouth is opened on a regular basis at high tide – and especially at Spring high tide – to allow sea-water in. So, any water that is abstracted will be replaced at the next high tide opening.

    Or are they perhaps worried that we will drain the Atlantic Ocean dry??

    At a time like this the authorities need the help and co-operation of citizens, so it is decidedly counter-productive to annoy them with stupid, pointless laws which reek of the syndrome “I am throwing my weight about – because I can”.

    1. As I understand it the point is public health. From a risk management perspective, it makes more sense to prevent people from abstracting water that is not suitable for drinking, and then not enforcing the rule, than allowing it and then not be able to control it or ensure the safety of people. The way water abstraction is done can also be a risk to the fauna and flora in the vlei.

      I agree though that the engagement with people in the drought, and beyond to co-create a Water Sensitive City, needs to change to allow the use of alternative water sources, responsible and in keeping with the best interests to people – rich and poor – and the wider environment. If the reason for prohibiting water abstraction is about protecting income through the sale of water services, then this also needs to be relooked to decouple income to the city from more sustainable practices like a diversity of water sources and overall demand reduction. Regulating this and making sure people stay safe is complex.

      1. Thanks to Bernelle for her reply. But I’m afraid it is not a very satisfactory one.

        Frankly, anybody stupid enough to drink vlei water without treating it deserves whatever happens to them.

        Making a rule and then not enforcing it is an exceedingly dubious way to run any authority. Specifically, in the present situation, many better-off households must be considering installing yacht-type desalinators, getting their input water from the vlei.

        That would help not only them, but also poorer folk, because the well-off would not be using their allocations, thus making more available for the poor.

        However, these machines cost around R100,000, plus installation. People will not spend that kind of money if, even only theoretically, they can be prevented from using the machine.

        It is fanciful to suggest that there might be a risk to fauna and flora by abstracting in the quantities required for household use.

        The real risk is in the opposite direction: clogged intake pipes due to the recent build-up of weed and algae. And the Council views this build-up as just something we must put up with.

        I wonder why said Council thinks Marina residents collectively pay them many millions in rates?

        I am appalled that “protecting income through the sale of water services” should even be a consideration.

        The present water crisis has been years in the making. If those in authority had not been asleep on the job, they would long ago have taken timeous action in the shape of installing large-scale desalinators. Had they done so there would now be no need to protect their revenue stream.

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