Westlake Wetlands work party July 2009.
Plastic bottles in Zandvlei – from bane to boon (or should that be boom?)
As the winter rains fall with increasing force they bring with them a tide of litter and pollution. Two litre plastic cool drink bottles are part of that unpopular tide that is such a bane to the vlei. However, an innovative initiative and some good partnerships are turning two litre bottles into a means to control an even greater bane, water hyacinth.
Water hyacinth, Eichornia crassipes, first appeared in the western rivers flowing into the Zandvlei in the mid 1980s. By the early 1990s it had become a major problem, choking the western water bodies, threatening flooding if it packed against the railway bridge and preventing free movement between the Westlake and the main Zandvlei. This South American plant has an explosive growth rate. It forms deep mats across the water cutting out light and oxygen leading to dying water bodies.
An indication of the size and density of hyacinth. The other Kingfisher waterweed harvester.
The City of Cape Town started using heavy mechanical equipment to clear the water hyacinth. Unfortunately this equipment could not reach deep into the reed beds and the water hyacinth just flourished again in the following year.
Residents of the Lakeside area, around the Westlake banded together under the auspices of the Zandvlei Trust to see how they could work with the City to tackle clearing those areas that could not be reached by City equipment.
A floating boom was conceived, and “built” to divide the water body into compartments and hold back the spread of the water hyacinth from one compartment to another. These booms required rope, floats, netting and weights for their construction. No funds were available so creative thinking was required.
A boom, with bottle floats, holds back water hyacinth in the Keyser’s River
Another factor threatening the Zandvlei, as mentioned above was, litter especially from the recreation areas. These areas are at the southern end of the Zandvlei. Because of the prevailing south easterly winds litter entering the water was blown to the northern end of the water body and ended up on the banks in the nature reserve around the bird sanctuary and wild areas.
However, the litter contained two litre cold drink bottles which floated to the northern end. “Floated”. Suddenly there was a source of the floats needed for the booms to control the hyacinth.
Westlake residents started collecting used two litre cold drink bottles. Several hundred came from homes, from litter collection. But still more bottles were needed. A local resident had a close connection with a company that was willing to donate new clean bottles to the project. So yet more booms could be made.Used rope and netting was found and in 2002 the first floating booms were in place.
Putting the floating booms in place
Most of the water hyacinth in the Westlake Wetlands has now been cleared. Crucial to the success has been the collaboration and partnerships between a range of players.
The responsible local authority the City of Cape Town provided equipment, management and budget for the major mechanical removal.
The floating booms now act as a security barrier against potential future infestation and to contain any areas still harbouring hyacinth. Over time the bottles deteriorate, mainly due to temperature changes causing expansion and contraction. These bottles are then replaced with new stock and the old bottles bagged and sent for recycling.
The effect of the clearing can be seen in an increase in fish activity. This in turn has led to an increasing number of kingfishers, herons and cormorants that, together with quite a number of people, come to fish in the cleared waters. The endangered Leopard Toad population also appears to have spread into some of the cleared areas.
"Our Fish Eagle".
A Goliath Heron reported by John Fowkes in July 2009, a first recording of this species at Zandvlei. The Malachite Kingfishers are seen regularly.
Colouful “returnees” enjoying the cleared vlei. The "Otter family" were seen soon after the hyacinth was removed. General water bird life has increased in the canals in the reed beds as well. Fish were more visible as well.
The carp are visible as well!
All these efforts are not just to keep the local “greenies” happy. There are far more important issues at stake. The Zandvlei is part of the Greater Zandvlei Nature Reserve that stretches inland from the False Bay coast near Muizenberg. The Reserve surrounds the Zandvlei which flows out into False Bay and plays two important roles.
Firstly it is a major recreation centre with sports fields and open lawns, sailing and canoeing clubs and youth group centres. Secondly it is the major estuary on the False Bay coastline and the only one that is a significant nursery for fish of False Bay. Because of these two factors the health of the water body is very important both for humans and for the environment.
So through innovative thinking, community action and collaboration with a range of partners, some litter has been turned into booms which are help to control an environmental threat – truly a boon.
John and Sandra Fowkes July 2009.