The Zandvlei water body is still closed to the public, seven weeks after its last catastrophic sewage spill.
The City’s manager for biodiversity management, Julia Wood, confirmed that this is the longest stretch of time the vlei has ever been shut due to E coli pollution.
Xanthea Limberg, mayoral committee member for water and waste, said it was not possible to completely seal off the vlei from its tributary system, and she blames the state of the estuary on the wide network of rivers and canals – stretching as far as Constantia/Kenilworth – all of which she says are polluted to some degree before they reach Zandvlei.
She says the most common pollutant by far are sewer blockages.
“Sealing off the estuary would result in the vlei reverting to a seasonal water body, impacting recreation and the Marina da Gama structure. For this reason, Zandvlei is rated only suitable for intermediate contact, such as sailing, canoeing, rowing and windsurfing,” Ms Limberg said.
She confirmed that the City did not test the vlei after each and every sewer spill in the catchment, but if it was suspected that the water had deteriorated beyond acceptable limits for intermediate contact, additional testing would be done to confirm that and determine when the vlei could reopen. Signage advised the public that the vlei was only suitable for intermediate contact, she said.
Ms Limberg also confirmed that the first public alert to the City about the Clifton Road sewage spill – which ultimately led to the seven week (and counting) vlei closure – had been reported on Wednesday May 19 – two days prior to the South African Canoe Marathon Championships which were held from Friday May 21 to Sunday May 23.
According to Ms Limberg, tests done on the water on Thursday May 20 did not pass control checks which meant the City could not report the results.
“Should we find that there was a failure in our quality control checks, it means that during this specific test run, there was something that compromised the quality of the results.”
The results of a subsequent test had only been available on Monday May 24, after the canoe event, according to Ms Wood.
Nevertheless, Ms Limberg said the City’s monthly test results had shown that E coli had started entering the vlei from Friday May 14, onward and the situation had been aggravated by the Clifton Road pump station failure on Saturday May 22, midway through the canoe event.
The vlei was only partially closed on Sunday May 23 and then fully closed on Tuesday May 25.
According to Professor Leslie Petrik, of UWC, there are many pathogens in sewage that can make humans sick, including ones that can cause gastroenteritis, cholera, dysentery, typhoid, hepatitis, meningitis and upper respiratory infections.
“I am sure there are many pathogens that may affect birds and fish too. But the main issue is antibiotic resistant bacteria which are developing due to the disinfectants and antibiotics in sewage.“
Those, she said, could cause harm to both animals and humans.
The City was struggling to keep E coli levels within acceptable levels, she said.
“Their allocated budget from central government is far too low, their rates base too limited. Their capacity to respond adequately and in a timely manner is too constrained to keep up with the ever growing population and our poop output, coupled with our extravagant use of chemicals,” she said.
During 2020, the City’s water and sanitation department cleared approximately 122 000 sewer blockages across Cape Town, the primary cause (75%) being misuse of the system, including the illegal disposal of foreign materials into the sewer system.
Ms Limberg said more than R350 million was spent on efforts to address this chronic – yet largely avoidable – problem.
In response to Marina da Gama residents who wanted to know the City’s plan to stop sewage flowing into the vlei, Ms Limberg said the City did ad-hoc maintenance in the catchment as well as strategic rehabilitation of infrastructure as far as resources allowed.
“However, given the scale of the challenge with sewer blockages, if we want to see quick results, we need residents to play their part and to help spread awareness,” she said.