Posted by: Saving Water SA (Cape Town, South Africa) – partnered with Water Rhapsody conservation systems – 30 March 2011
Issued on behalf of: Liesel James: Founder of Little Green Fingers
On 26 March 2011 a Water Awareness Event focusing on a local issue took place at Blue Water Café, Imhoff’s Gift. The community of South Peninsula, City of Cape Town and Wastewater Treatment Works (WWTW) were invited to discuss the ongoing eutrophication causing toxicity in Wildevoel Vlei and insisting on finding a successful solution.
50 people including local residents, environmental organizations and volunteer groups attended.
The Wildevoelvlei wetlands form an integral part of the wetland systems in the Noordhoek Valley. Originally the vlei was seasonal and dried out over the summer months. Rainfall, groundwater seepage, stormwater run-off and spring tides regulated the water level.
In 1977, the Wildevoelvlei WWTW was commissioned and the vlei became a permanent water body due to the treated effluent being discharged into it.
Wally Peterson founder of Kommetjie Environmental Awareness Group (KEAG) who was previously involved in trying to resolve this problem gave a comprehensive history of Wildevoelvlei at the event.
He said, “WWTW was upgraded in 1996, but the development in the valley has way exceeded the expected population growth as predicted in the EIA. This placed WWTW under huge pressure through an increase of treated effluent entering the vlei, and through an increase in quantity and decrease in quality of the nonpoint stormwater run-off discharged into the vlei.”
He went on to say that in response to this crisis, a number of emergency measures were implemented including lowering the water levels by opening the mouth, and dropping salt into the vlei from helicopters as Blue-greens struggle in saline water bodies. “This was effective in the short term but toxic algae blooms have continued to occur. The most recent bloom being in December 2010 when media reports warned locals, their pets and visitors to away from the water” he says.
Prior to 1998 the vlei was relatively stable due to the presence of a population of Sago pondweed. It provided nesting material, shelter and food for a variety of birds and aquatic life. Many species of waterfowl and even large flocks of flamingoes and pelicans were regular sightings. The last resident flamingoes were here in 2002.
In 1998 some form of pollutant entered the water bodies and this led to a mass die off of all of the pondweed. This is still an unsolved mystery.
This enabled a species of blue-green algae to grow extensively. Cyanobacteria such as Microcystis proliferate in summer when conditions are favourable. These blue-greens thrive on high levels of phosphorus and soon produced toxins. The vlei turned a bright green in colour and the water became toxic. The toxins produced in Wildevoelvlei entered the marine food chain and became concentrated in the mussel beds at the outlet to the sea. A ban was imposed on all mussel collecting and warning signage was erected.
“This is a great threat to members of Ocean View and Masiphumulele; two local townships that rely on this shellfish to supplement their food security and income. The children from these areas often play in the mouth, as this is the nearest beach” said Peterson.
Management options have been explored by the City of Cape Town and these include the reduction of sewage effluent, improving the quality of effluent and storm water, reducing the internal nutrient load and dilution and flushing. These options all have cost implications and nothing has been done over the last decade except for an unsuccessful attempt to re-grow pondweed.
On 13 January 1999 a year after the significant algae bloom, Bryan Davies and Anja Gassner wrote a comprehensive report to the Catchment Management section of the Cape Metropolitan Council mentioning some facts including:
“Commercial washing powders contain by weight between 15% and 30% phosphate, the substance that is at the bottom of the pollution problems recounted in this report for all the vleis of the Noordhoek Valley, and for Wildevoëlvlei in particular. This means that every kilogram box of washing powder may yield up to 300g of phosphate. Waste Water from homes contains large quantities of the material.”
“We are convinced that it is an imperative that residents of the Noordhoek Valley – indeed, the entire area under the control of the CMC – be forced, using appropriate Bye-Laws and incentives, to use grey water (water from baths, showers, hand basins and washing machines) for irrigation purposes,” said Anja Gassner.
“The tools for this purpose are already available and have a proven track record. The strategy will have a dual benefit: 1. The reduction of the phosphate loads reaching the sewerage treatment works by as much as 50%; and 2. Reduction of water demand throughout the area under the control of the CMC, thereby avoiding the need for further costly water augmentation schemes.”
This excerpt from the report starts on page 50, Paragraph 7.5.6, (quoted verbatim)
Follow link http://www.savingwater.co.za/2010/03/06/10/commercial-washing-powders-destroy-wetland/
The toxins are a health risk that can cause liver damage and can kill animals and humans if ingested in large enough quantities. They can also cause hay fever and ear and eye infections. It was interesting to note that many of the residents living close to the water suffer from allergies and arthritis and other joint pains. Algae are airborne.
Blue-greens also affect the functioning of the vlei as Oxygen in the water is depleted causing other organisms such as fish to die. The most recent mass die-off of fish occurred in April 2010.
“Until action takes place it would be very shortsighted for any further development to take place in the valley,” concluded Peterson.
“Sadly no one was present from WWTW and City of Cape Town. We want to find a solution and work with City of Cape Town to achieve this”, said Liesel James founder of Little Green Fingers, organisers of this event.
James said that following the event a new entity has been born, Creating Change: A coalition of new, existing and old members who are investigating, finding solutions and reporting on the rehabilitating of Wildevoel vlei. Scientific evidence to understand exactly the source of this local problem is currently under investigation by Resource Ballast Technology who is testing water samples currently been cultured.
Once the scientific evidence is confirmed, appropriate solutions will be sought and presented to City of Cape Town and WWTW.
“The power of community is the future for positive change. It is amazing how many local environmental experts have come on board to assist in this process” concluded James.
Liesel James may be contacted at 0711987875 or