Environmental activist group RethinkTheStink has raised the alarm following what it describes as a heartbreaking setback at Milnerton Lagoon, after the discovery of dead fish recently — including a large sunfish — just as signs of ecological recovery had begun to re-emerge.
According to the group, fish had recently returned to the lagoon and a seal had even been spotted, offering hope that years of pollution might finally be easing. That optimism was short-lived, the group said.
“Another sewage spill has once again poisoned the lagoon, leaving dead fish in its wake,” Rethink The Stink said.
“With water quality test results not updated since 4 November, and repeated pleas for answers met with silence, the community is left helpless and angry — denied transparency, accountability, and the basic right to know what is happening to our water.”
City responds to sunfish discovery
Responding to the concerns, the City of Cape Town’s Deputy Mayor and Mayco member for spatial planning and environment, Eddie Andrews, said the City is aware of the sunfish incident and moved swiftly to remove the animal.
“The City is aware of the sunfish, as we removed the animal after the Two Oceans Aquarium had measured and sampled it for genetic research. We are not aware of any other dead fish from last week,” Andrews said.
He explained that sunfish are open-water pelagic species and do not naturally inhabit shallow lagoon environments.
“This sunfish most likely entered the lagoon at high tide, became disoriented, and stranded when the tide receded. The fish measured approximately 2m by 2m, while the lagoon mouth is significantly shallower than two metres at low tide,” Andrews said.
The City added that weekly dissolved oxygen monitoring shows that while the upper reaches of the Diep River remain oxygen-poor due to pollution, oxygen levels at the lagoon mouth — where the sunfish was found — meet or exceed acceptable levels of 4–8 mg/l.
Mayco member for water and sanitation Zahid Badroodien said the water and sanitation’s relevant sewer team inspected the area and found no sources of contamination. The directorate’s Water Pollution Control Unit is also conducting their own investigations into the matter.
“Regarding the water quality test results statement, the public dashboard and Open Data Portal experienced technical difficulties during November and December last year as a result of the City’s GIS Software Upgrade Project. Relevant departments are currently configuring the system to enable weekly data synchronisation. As a result, the dashboard is not yet fully automated and Inland Water Quality data continues to be uploaded manually each month as a temporary solution. Download functionality has also been restored,” Badroodien said.
Residents remain unconvinced
Despite the explanation, residents living near the lagoon say trust remains low, with many feeling exhausted by repeated incidents and a lack of timely public information.
“We keep hearing technical explanations, but what we see with our own eyes is a lagoon that keeps getting sick again and again,” said Milnerton resident Sarah Jacobs.
“If water quality tests are being done weekly, why aren’t the results shared immediately with the public?” asked local kayaker and resident Mark Petersen.
“We were finally starting to feel hopeful, then suddenly there are dead fish again. It’s emotionally draining to care so much and feel ignored,” said Woodbridge Island resident Leanne Williams.
“The City keeps talking about long-term plans, but people who live here want to know what’s happening now,” added Yusuf Moller.
Ongoing intervention programme outlined
The City says the lagoon remains the focus of a multi-year, multi-pronged intervention programme, details of which were shared at a public meeting held on Wednesday 29 October 2025.
Residents were briefed on sewer and pump station upgrades, improvements at the Potsdam Wastewater Treatment Works (WWTW), strengthened maintenance schedules, and ongoing environmental monitoring.
“The City thanks residents for their ongoing engagement as we roll out these multi-year interventions. The reports presented show steady progress being made, which reflects our commitment to restoring the ecological health of the Milnerton Lagoon and the wider Diep River catchment,” said Badroodien.
Infrastructure upgrades and progress
According to the City:
- Over 12km of sewer lines were proactively cleaned between May and October 2025.
- Monthly sewer blockages in the Lower Diep and Rietvlei catchment dropped from 4 270 in October 2024 to 3 460 in September 2025.
- Major sewer rehabilitation projects have been completed or are under way in Montague Gardens, Milnerton, Century City and along the R27.
- All 112 pump stations in the Blaauwberg region are equipped with telemetry for early fault detection, while significant upgrades — including a R61 million sand trap at Koeberg Road Pump Station — have already reduced overflow impacts.
The City’s R5,2 billion Potsdam WWTW upgrade, launched in April 2023, has passed 60% completion and remains on track for completion in 2027/28. Once fully commissioned, the upgraded facility is expected to deliver major improvements in effluent quality and environmental performance.
While City officials maintain that progress is being made, activists and residents insist that real-time transparency, faster communication, and public access to environmental data remain critical.
