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Cape Town nature reserve under siege as algal toxins and sewage pollution threaten biodiversity

Cape Town nature reserve under siege as algal toxins and sewage pollution threaten biodiversity
City of Cape Town walk about the Zeekoe catchment to identify all the major pollution sources affecting this catchment area. (Photo-Zahid Badroodien / Facebook)
Kristin Engel
By Kristin Engel
22 Dec 2024
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Stakeholders expressed dismay that despite alerting the City of Cape Town to a major source of pollution in the vlei more than a year ago, the City had not been forthcoming in addressing the problem. Now the situation has escalated with the vlei closed to all recreational activity since 12 December 2024 due to an algal bloom.

If you are looking for a nature reserve to visit in Cape Town this holiday season, you might want to reconsider False Bay Nature Reserve — or at least the Zeekoevlei section after it was closed to all recreational use due to a blue-green algal bloom with high concentrations of microcystin toxins.

Stakeholders expressed dismay that despite alerting the City of Cape Town to a major source of pollution in the vlei over a year ago, the City had not been forthcoming in addressing the pollution in the vlei. This is in addition to alleged National Environmental Management Act (Nema) transgressions by City contractors/officials and service requests that were allegedly closed without action taken.

Now the situation has escalated with the vlei closed to all recreational activity since 12 December 2024 due to the algal bloom. The vlei has already suffered from decades of human misuse and nutrient enrichment. 

Along with reports of sewage incidents at the northeast Rietvlei section of the Table Bay Nature Reserve between 2019 and 2024, the matter has raised concerns about the lack of accountability by the City when dealing with pollution incidents in its protected areas and nature reserves. 

Friends of Zeekoevlei and Rondevlei vice-chairperson Tom Schwerdtfeger told Daily Maverick that they alerted the City to major pollution in the vlei from Phumlani Informal Settlement more than a year ago, but no action had been taken until the vlei was closed.

Friends of Zeekoevlei and Rondevlei was adamant that concrete action and a solid plan should have been developed a year ago when it first identified Phumlani as a problem area. 

“We have had seven meetings with the City regarding this issue, and no real progress has been made. I feel sorry for the many dedicated staff who do try their best to improve the situation — only to be let down by a few rogue colleagues who stand in the way of progress,” Schwerdtfeger said.

Wastewater flows into Zeekoevlei in False Bay Nature Reserve. (Photo: Supplied by Friends Of Zeekoevlei And Rondvlei)



Dr Liz Day is a freshwater ecologist specialising in river and wetland water management and rehabilitation, chairperson of the Zeekoe Catchment Management Forum, and a member of the False Bay Protected Areas Advisory Committee.

Day said that some blue-green algal blooms produced toxins, including microcystin toxins — which were very high at Zeekoevlei and resulted in the closure. If ingested, these toxins can cause liver damage and other harmful effects, while exposure of skin to infected water can cause rashes and other problems.  

Day said that in a nature reserve such as Zeekoevlei, exposure to toxic water could affect fauna such as the Cape clawless otter, water mongoose, and birdlife, as well as fish, and there was evidence in literature of the harmful effects of air-borne toxins. 

Other risks are mass fish die-offs, either because of toxicity effects, or (more probably) because of low oxygen in the water, often associated with mass algal growth.

Since 12 December, all recreational activities have been prohibited at the Vlei. This, according to Friends of Zeekoevlei and Rondevlei, threatens the national regattas planned for 2025 as well as businesses such as the Zeekoe Vlei Yacht Club.

In addition, Friends of Zeekoevlei and Rondevlei cannot deploy its Green Team to remove the large amounts of solid waste when there are such high levels of sewage in the system — they typically remove 140 bags of litter per day — so the build-up over these times sets these efforts back enormously.

Lack of accountability


Schwerdtfeger and the Friends of Zeekoevlei and Rondevlei felt that there has been a lack of accountability at the City of Cape Town in dealing with pollution incidents at its waterbodies, protected areas and nature reserves.
In the past, there have been many examples around Zeekoevlei and other locations in the City when Nema laws have been broken. And to the best of my knowledge, nobody has ever been held accountable for terrible decisions like pumping sewage into the ponds at Rondevlei when the nearby Pump Station packed up. Or when bulldozers arrive on a site to clean up a mess and do even more damage by destroying vegetation that has been restored to an area.

“The list goes on. Only when someone is held accountable for breaking legislation will the situation improve,” Schwerdtfeger said. 

Multiple service requests (C3s) logged by False Bay Nature Reserve on 12 December were all closed without any action being taken by the City’s Department of Water and Sanitation, according to Schwerdtfeger.

In response to this, the City said that for one service request referenced here, a sewer blockage was caused by sand and was resolved according to the feedback received. The City was unable to locate the second service request, and the third one contained an incorrect reference number.

In Friends of Zeekoevlei and Rondevlei’s opinion, top City management needed to be more transparent about how bad the situation was in certain areas within the City.  

“Nobody wants to hear bad news — but we have to face these challenges head-on and take the required action one step at a time,” Schwerdtfeger said.

Caroline Marx, director of Rethink The Stink, a local NPO in Cape Town, warned: “The City needs to deal decisively with the sewage-related pollution affecting Zeekoevlei or risk another total ecosystem collapse, as happened at the Milnerton Lagoon.” 

Daily Maverick also noted incidents from the Flamingo View Homeowners Association of multiple and at times continuous sewage incidents at the northeast Rietvlei section of the Table Bay Nature Reserve between 2019 and 2024, especially due to a failed pipe repair in that section, according to Kevin Sherman from the association. 

Pollution from Phumlani informal settlement that runs into Zeekoevlei in False Bay Nature Reserve on 19 December 2024. (Photo: Supplied by Friends Of Zeekoevlei And Rondvlei)



Sherman lives along this section of the reserve and has observed and documented sewage overflows and pollution in the Rietvlei Nature Reserve area since 2019. These incidents include stormwater mixing with sewage and consistent failures to manage or remediate the problem effectively.

Sherman said that the City had allowed a temporary repair in 2020 to remain in place until that pipe section burst in 2023, resulting in a six-month repair effort that was plagued by delays and regular sewage spills. After this, efforts to mitigate the impacts were temporary and ad hoc.

“After I sent photos of leaky temporary pipes, the contractor would wrap more rags, but within days, the problem recurred elsewhere,” Sherman said. He alleged that transgressions by City officials, guiding sewage directly into the nature reserve during a pipe repair, were reported but delayed, and temporary action was taken.

In response to the allegations, Deputy Mayor and Mayoral Committee Member for Spatial Planning and Environment, Eddie Andrews, requested that any person who had information about these alleged contraventions report this to the City for investigation.

Addressing pollution sources


As for how significant the settlement’s contribution was to Zeekoevlei,  Schwerdtfeger said that at a meeting with officials on Thursday, 19 December, mayoral committee member for water and sanitation Zahid Badroodien requested that this and all other points of sewage into the catchment be quantified, to determine the impact and solution to each point. 

“The proximity of Phumlani to Zeekoevlei is of great concern — being about one kilometre from the Ramsar site. Nature is not given the chance to do its thing and break the sewage down before it hits the Vlei,” Schwerdtfeger said.

He added that the largest contributors of sewage appear to be from Gugulethu and Brown’s Farm, but said there were many different points where sewage entered the canal.

Day said there needed to be focused attention on addressing the multiple sources of pollution in the upstream catchment, including the replacement of major sewers and diversion of inflows of raw sewage to sewers, rather than allowing for it to be “treated” in wetlands and rivers that did not have the capacity to deal with the loads.    

“There is no quick fix for the current algal bloom,” Day said.  

Day said there needed to be a step-by-step approach that looked at finding practical measures to address each of the known point sources of pollution, at source or downstream.

In response to these matters, Andrews said: “The dredging of the nutrient-rich sediments in Zeekoevlei is due to start early in the new year. This will assist with the reduction of the pollution entering the system, and residents can look forward to an improvement in the water quality and health of the vlei. The Zeekoevlei weir is also on the cards to be upgraded, which will assist with the annual flushing of the system.”

The City is also researching various bioremediation solutions to address pollution at various water bodies.

City of Cape Town response


In the City’s response to Daily Maverick, Badroodien said the population in the upper parts of the Zeekoe Catchment had been steadily increasing, and this had led to a significant rise in solid waste output, posing a substantial challenge to various departments within the City.

“Regrettably, some residents resort to illegal dumping, discarding items such as furniture, animal carcasses, soiled diapers, and construction materials directly into the local waterways. This practice not only pollutes the environment, but also complicates waste management efforts,” he said.

As for Phumlani, Badroodien said that despite the construction of chemical and regular flush toilets in November 2023, the local community continued to dump waste, grey water, night soil, and other illicit discharges into the channel. 
This persistent issue has resulted in little to no improvement in the water quality entering the vlei. In response, the City is now considering more significant interventions, such as converting the channel into a closed pipe or culvert network.

“However, this strategy carries risks. Once the closed network is installed, further land invasions could occur, complicating the City’s ability to access and maintain vital infrastructure,” Badroodien said.

Despite the City’s efforts to increase the frequency of routine maintenance along the Big Lotus Canal, there had been a noticeable surge in the volume of waste and debris entering the waterways. Badroodien said this ongoing issue underscored the need for enhanced waste management strategies and community engagement to mitigate the environmental impact.

The City has developed a Pollution Abatement Strategy Action Plan, a document that tracks various capital and operational projects aimed at mitigating pollution within the catchment. 

Pollution from Phumlani informal settlement that runs into Zeekoevlei. (Photo: Supplied by Friends Of Zeekoevlei And Rondvlei)



A photograph taken on a City of Cape Town walkabout at the Zeekoevlei catchment to identify all the major pollution sources. (Photo: Zahid Badroodien / Facebook)



Badroodien said that this plan involved coordination among multiple directorates, departments, branches, and sections.

In addition to ongoing investigations into pollution sources, he said the City had established additional routine sampling locations for water quality monitoring — which had enhanced the City’s ability to “respond to pollution incidents swiftly and identify hotspot areas more efficiently”.

Significant improvements had been made to the City’s sewer reticulation system, and these upgrades were expected to reduce the frequency of sewer collapses and overflow into the stormwater network, thereby contributing to better overall water quality management.

“The City is committed to working with various stakeholders, including the local catchment forum and the public, to improve the inland water quality at Zeekoevlei. Relevant teams are activated when there are reported pollution incidents that impact the river so that they can resolve the matter in the shortest time possible,” Badroodien said. 

As part of the City’s incident management protocol, the Water and Sanitation Directorate also reports significant pollution incidents and action steps to the Department of Environmental Affairs and Development Planning, the Department of Water and Sanitation and the Department of Forestry, Fisheries and the Environment for accountability. The Department of Forestry, Fisheries and the Environment is only informed in the event of an incident affecting the coastal environment. DM

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