Milnerton Lagoon, among the City of Cape Town’s most polluted water bodies, empties into Table Bay. (Photo: Jean Tresfon) 
A newly published peer-reviewed study led by researchers from the University of Cape Town (UCT) and collaborating institutions has ignited a fierce dispute over water quality governance in Cape Town.
The study alleges repeated interference, denialism and misrepresentation of science by the City of Cape Town.
The City of Cape Town responded, stating, “these allegations and assertions cannot be further from the truth”.
The study, Contaminant Denialism in Water Governance, in the Water Resources Research journal, critically examines how official public communications and institutional structures may contribute to what the authors term “contaminant denialism”. This is the downplaying or obfuscation of water contamination issues in the city’s rivers, estuaries and coastal waters.
Lead researcher on the study, Professor Lesley Green — a paddler, professor of Earth politics and director of Environmental Humanities South at UCT – said the signs of the pollution crisis that they had spent more than a decade researching weren’t confined to academic papers or research data. They were visceral and undeniable, having both public and marine health impacts.
Green said the tipping point for her personally, and why it was necessary to conduct the study, was a massive sewage spill in Zeekoevlei in June 2021, where she discovered that her local ratepayers’ association was pressured not to share contaminant data they received from the city.
She alleged further instances of intimidation against scientists, many of whom contributed to this study, and of city officials approaching her off the record, frustrated by their inability to speak out about the data they were seeing.
Green said that this wasn’t just about dirty water, but what she alleges is a fundamental breakdown in transparent governance, a deliberate undermining of scientific integrity and a betrayal of the public trust.
This study is the culmination of extensive research led by Green, Cecilia Ojemaye, a UCT researcher, Dr Jo Barnes, senior lecturer emeritus at Stellenbosch University, Leslie Petrik, professor/leader of the Environmental and Nanoscience Research Group at the University of the Western Cape (UWC), Nikiwe Solomon, a UCT senior lecturer and Vanessa Farr, senior research fellow at Sheffield Hallam University.
The study’s allegations paint a picture of a municipality more intent on managing public perceptions, especially the marketing of Cape Town as a tourist destination, than on more effectively communicating public risks of pollution in water bodies.
In its response, the City of Cape Town said bluntly that “these allegations and assertions cannot be further from the truth”.
Public transparency, trust, and study findings
The authors have alleged repeated denial and minimisation of contamination issues with the city, downplaying the severity of pollution in rivers and at beaches, despite independent studies showing high levels of microbial contaminants that pose serious public health risks.
Read more: After bacterial infections, Strand beachgoers call for effective water-quality flag system
They also found the use of misleading science communication tactics by the municipality, with distinct methods to obscure scientific data for public understanding.
These methods include withholding or selectively releasing test results, using statistical averages that mask contamination spikes, and presenting isolated water samples as representative despite environmental variability.
Read more: Tides of controversy: coastal water quality becomes a battleground in Cape Town
The study also addresses institutional conflicts of interest. The researchers argue that having the same municipal departments which are responsible for managing water quality also funding scientific research/oversight of this quality creates a conflict that may compromise scientific independence and transparency.
On top of this, the research team has faced public denunciation by city officials and political parties, online harassment and demands for apologies over laboratory results which do not match the city’s results.
Read more: Dear DA and City of Cape Town: Please stop the bullying tactics
The study criticised the city’s reliance on outdated wastewater treatment and monitoring approaches like point sampling methods, rather than predictive flow modelling, which would better inform the public about contamination risks.
The research also documents widespread contamination, with some popular beaches at times exceeding safety limits for bacterial pollution. This contamination often stems from untreated sewage discharges, malfunctioning treatment plants, leaking sewerage systems and pollution from informal settlements.
Read more: Urgent call for action: Cape Town’s marine outfalls persistently fail to meet regulatory standards
The authors have urged the city to end conflicts of interest, make all water quality data publicly and promptly available, adopt modern predictive modelling for contamination risks and protect independent science from political interference.
Green, in an interview with Daily Maverick, said: “Our intention is not to simply criticise, but to highlight a systemic issue that needs to be addressed for the benefit of all Capetonians… We believe that robust, independent science is an asset, not a threat. When scientific findings are dismissed or distorted, it prevents effective problem-solving.”
Read more: Environmental concerns rise as Cape Town secures extended deadlines for Milnerton Lagoon upgrades
Read more: Cape Town fights uphill battle against ocean and waterway sewage spills
A firm rebuttal from the city
In light of the serious allegations made in the study, Daily Maverick asked the city for its response, and it did not mince words in its rebuttal.
“We refute the allegations made in this study regarding denialism, interference, or misrepresentation of scientific data,” a spokesperson for the City of Cape Town said.
The city further elaborated on its extensive water quality monitoring programmes and the sheer volume of samples collected and tested annually.
“The city has always been very clear and transparent about the challenges we are facing regarding urban pollution, the interventions needed, and the allocation of resources in finding long-term solutions,” said the spokesperson.
The spokesperson said the city’s compliance with national water quality standards and ongoing multibillion-rand investments in wastewater treatment infrastructure were evidence of its commitment to improving water quality. The spokesperson also noted that the city regularly published water quality data and engaged with various stakeholders, including academic institutions.
Regarding the specific claims of withholding data or obstructing research, the spokesperson said that data was made available under access to information policies and that legitimate research requests were always considered.
The spokesperson suggested that any perceived difficulties might stem from the complexities of data interpretation or the need to protect sensitive information.
The spokesperson encouraged people to independently assess the full spectrum of reports and data publicly available on pollution in Cape Town and compare that to any municipal website of any city globally, but especially in South Africa.
“We believe we are far ahead of equivalent cities in that regard. The city has always been very clear and transparent about the challenges we are facing regarding urban pollution, the interventions needed, and the allocation of resources in finding long-term solutions,” said the spokesperson.
In recent years, under Cape Town Mayor Geordin Hill-Lewis’s administration, there has been a more concerted effort to engage with scientists and the public with more transparency and rigorous water quality monitoring.
Since adopting an Open Data policy in 2021, the city has made all water quality data publicly accessible through its website, including detailed “Know Your Coast” reports. The city maintains that its monitoring and reporting methods adhere strictly to national guidelines, ensuring that the public receives accurate and timely information about water quality across the region.
But there is still a deep chasm in understanding and public trust. Green says this is precisely why the study is so critical.
The study implicitly, and at times explicitly, calls for a fundamental shift in the city’s approach to environmental governance. It advocates for greater transparency, a genuine embrace of independent scientific scrutiny and a collaboration that brings together government, academia, civil society and local communities in a shared effort to restore Cape Town’s water resources.
Green said, “We acknowledge some recent steps by the mayoral office, including reversing the 2021 by-law that prohibited independent water testing and releasing summer beach water quality data. This is a start, but much more needs to be done to restore public trust in science and secure clean, safe rivers, lakes and beaches for all Cape Town residents.”
In response to the report, the city spokesperson said the city would address all allegations made via the submission of a formal academic response to the journal where the study was published, as this was the correct process to be followed in responding to a publication of this nature.
“The city will make this publicly available once done,” the spokesperson said. DM
Disclosure: Some of this journalist’s previous reporting on Cape Town’s water quality is cited as source material in the academic study discussed in this article.