Cape Town's Zandvlei faces recreational shutdown amid alarming E. coli contamination levels

A significant portion of Zandvlei, Cape Town’s only functioning estuary in False Bay, has this week been closed to all recreational water activities by the City of Cape Town as the authority of the Zandvlei Nature Reserve.

This temporary closure comes after consecutive water quality readings revealed E. coli levels exceeding 4,000 CFU/100ml, surpassing the threshold for intermediate contact recreation. 

While the exact source of the contamination remains under investigation, observations from various stakeholders and the City of Cape Town indicate that compromised inflows from the Sand River canal are a major contributing factor.

Officials are still conducting water quality monitoring and will continue in the coming weeks. They said the affected section would be reopened once results consistently returned to acceptable levels.

The closure, according to various stakeholders, reveals a deepening environmental crisis facing Zandvlei and its broader catchment. 

The recurring issue of elevated E. coli levels, particularly during winter with rainfall flushing pollutants, has been described as a systemic problem across water bodies that stakeholders say demands urgent and comprehensive intervention beyond temporary closures.

Zandvlei is an estuary, the last remaining functional estuary in the entire False Bay, and is a highly complex and integrated system starting in the Constantia mountains as the catchment area and ending at Muizenberg's Blue Flag beach.

The temporary closure of a large section of this estuary has already significantly affected both recreational users and the broader community. The closure also extends its reach to local bathers and surfers at Muizenberg Beach, where the estuary flows into the sea, raising concerns about their health and safety due to the compromised water quality. 

Businesses along the Muizenberg beachfront, heavily reliant on beach users, could also face potential “catastrophic” economic repercussions if the pollution issues persist.

This is on top of the impact on Zandvlei’s fragile ecosystem. 

Jennifer Louw, the chairperson of the Catchment Forum, told Daily Maverick: “Currently the usability of the vlei is not ensured due to the compromised state of the catchment from top to bottom.

“The waters are often contaminated and huge amounts of pollutants lie trapped in the sediment that has accumulated in the vlei. This is a result of the condition of every river and stream fed by stormwater from every road and every roof and paved area in the catchment.”

She said their vision was to see the vlei improve from its current ecological rating of level D to level C, and then to Level B. Louw said the levels were graded from A, which is pristine, to F, which is basically permanently eutrophic.

“This is a long-term goal that needs the comprehensive Catchment Management Plan backed by policy and policing in order to achieve. We must aim high as only this way can we achieve improvements,” said Louw.

Read more: South Africa’s wetlands are disappearing faster than we can restore them

Zandvlei’s hard-won progress jeopardised by pollution

Liz Day, a specialist freshwater ecologist, said that water quality and associated ecosystem function had been improving in Zandvlei over the past one to two years, with this being “Cape Town’s only current functional estuary”.

Day said that while healthy estuaries may be able to recover quickly from short-lived sewage spills, prolonged exposure to raw sewage could have major long-term ecological effects. 

“Zandvlei has been the only estuary in the city that has been improving over the past one or two years, and this setback needs to be taken very seriously and addressed, particularly in light of the investment by the City in the Liveable Urban Waterways projects in this catchment,” said Day.

The exact source of the pollution behind this recent closure is still under investigation, but Day said that the site ZA02S, where the E. coli level was exceeded, lay downstream of the Westlake River, the Sand Canal and parts of the Marina. 

Day said that any of these might have been exposed to sewage overflows. 

“High E. coli readings usually indicate inflows of raw sewage, which are associated with phosphorus enrichment (promoting often-nuisance plant growth), elevated ammonia (toxic to aquatic organisms at low concentrations) and high chemical and biological demands, which can result in plugs of low oxygen passing through aquatic ecosystems,” said Day.

Impact on the local community 

Damian Gibbs, the chairperson of the Zandvlei Trust, told Daily Maverick that closing Zandvlei had profoundly affected recreational and professional sporting use. 

Zandvlei had hosted national, provincial and world championship paddling events, regular school sailing programmes and inter-school regattas, and was a training venue for international professional windsurfers. 

Gibbs said regular closing of the water had had a negative effect on these activities. This was on top of other cultural ways Zandvlei was used; it was often used by youth-oriented organisations including scouting, guides and sea cadets, which held regular water-based programmes. 

As Zandvlei was an estuary and flowed out into the sea at Muizenberg Beach, Gibbs said the water quality should also be of great concern to local bathers and surfers. 

“The businesses along Muizenberg beach front and surrounding area are largely supported by regular beach users, and should Zandvlei not be able to cope with the regular pollution levels, the economic ‘run-off’ effect on surrounding businesses would be catastrophic,” said Gibbs.

In addition, a direct impact was that groups working at the vlei and in the waterways that flowed into the vlei were not able to carry out their work as usual. 

Louw warned that litter and invasive plants could not be removed from the water where it was deeper, and said wading was necessary, “thus their work is being hampered”.

“We appeal to the City to take more proactive measures to address the water quality in Zandvlei. It is a regular winter cycle with the fluctuating E. coli levels and regular closure warning notices associated with rainfall flushing pollutants from the catchment area into and through Zandvlei, and out to sea at Muizenberg Beach,” said Gibbs.

City spokesperson Luthando Tyhalibongo told Daily Maverick that their investigation into the source of the elevated pollution levels involved pollution tracking of all possible sources, and additional sampling was ongoing.

When asked how frequently officials were conducting water quality monitoring, Tyhalibongo said: “Resampling is subject to capacity, but is aimed for a minimum of weekly until the situation changes. The next sampling effort has already been confirmed for midweek, and again early next week.”

The E. coli reading must be below 4,000 CFU for safe recreational use. 

The root causes of pollution

Gibbs pointed to several factors contributing to the pollution, including concrete canals used as dumping grounds, sewage spills from pump failures, businesses along the canals dumping oil and other liquids, runoff from farms that used fertilisers, herbicides and insecticides, and the City spraying Glyphosate on verges after which runoff ended up in the stormwater systems and eventually in Zandvlei.

Louw, from Catchment Forum, said there was a need for “constant monitoring and being the eyes on the ground to help the City identify a problem”.

Blockages in the system were “most often caused by residents and businesses flushing inappropriate materials into the systems, as well as residents and restaurants adding fats that then adhere to pipes and cause narrowing and blocks”, said Louw.

This necessitated that communities and businesses be constantly urged to apply better practices to waste disposal.

Louw said the dire state of the Zandvlei catchment required collective responsibility, as upstream residents significantly contributed to downstream pollution through improper land management and waste.

“The troubles downstream are often only experienced by residents there, yet residents upstream are a major part of the problem… Only collectively, by placing the health of the ecosystem that we all rely on first, can we achieve the goals of a healthy vlei and its catchment into the future,” said Louw.

Gibbs said that the Zandvlei Trust actively monitored and emptied garbage collection nets in the Sand River, which was “soul-destroying work to witness the trash coming down the river”, said Gibbs. 

Thee amounts were in excess of 75 truckloads each winter — and this only accounted for visible pollutants. 

Louw warned that with rapidly increasing development, both residential and business pollutant-rich runoff was increasing, and the catchment system could not cope with these increases. 

“From top to bottom and across that catchment a plan based on a vision of healthy water bodies needs to urgently be compiled. Unless we develop our city in a way that supports a healthy water cycle, our waters will continue on the downward trajectory that we are on,” said Louw.

The city’s Liveable Urban Waterways projects are an important part of Cape Town’s future water health, and it is significant that the City earlier this year reversed a budgetary decision that was set to delay key river rehabilitation projects under this programme for up to 10 years. 

These projects, along the Grootboschkloof, Westlake and Keyser rivers within the Sand River Catchment, will commence in the 2025/26 financial year and are designed as nature-based solutions to protect the catchment from pollution and degradation. 

Read more: Cape Town river rehab projects to go ahead after City reverses decision to delay budget spend

But Louw said the 13 projects planned for the catchment in this programme would not be able to mitigate the impacts that urbanisation would have on the sustainability of the environment. 

“The time has come to place the health of the environment as a top priority next to economic growth for our city. The Catchment Management Plan is critical to the health of the vlei, to property values all along the waterways and to the health and economic wellbeing of our catchment area,” said Louw. 

Tracing pollution to its source

The City’s Scientific Services Branch is currently resampling affected areas of the vlei, including an additional sampling point, to pinpoint the source of pollution. 

Mayoral Committee Member for Water and Sanitation, Zahid Badroodien, said: “Initial speculation is that it is a blocked sewer overflow entering the Sand River Canal. River results support this conjecture. Results are expected in the next 24 hours.”

Badroodien said there was a pervasive issue of pollution in Cape Town's urban waterways. 

The contamination stemmed from various human activities, including littering, illegal dumping, night soil and greywater. 

Despite ongoing waste removal efforts, Badroodien said illegal dumping and foreign objects in sewer manholes continued to cause blockages and overflows into stormwater systems.

Badroodien reiterated the City's commitment to improving water quality within its rivers, acknowledging existing legal, budgetary and other constraints. 

To address these challenges, the City’s Water and Sanitation Directorate was investing a substantial R4.9-billion for the 2025/2026 financial year. This investment targeted critical infrastructure upgrades, including R31-million for Liveable Urban Waterways projects and R1.81-billion for the expansion and upgrades of wastewater treatment works across the city. 

On Thursday, the City announced that it would be going ahead with the Sand and Langevlei Canals confluence, having secured environmental authorisation from the Western Cape Department of Environmental Affairs and Development Planning. 

This paves the way for a project expected to deliver multifaceted benefits to the Zandvlei catchment, including reduced silt and litter entering Zandvlei, leading to improved water quality, enhanced aquatic biodiversity, and a renewed wetland area. DM