The green algae in Milnerton Lagoon is non-toxic, the City of Cape Town said on Monday.
The City’s scientific services branch tested the water quality at the lagoon to check for a harmful algal bloom, following a fish die-off there a few weeks ago (“City to probe lagoon fish deaths,” Tabletalk, March 9).
The City’s water and sanitation directorate says it is still investigating possible sources of this algal bloom, but the algae in the water is non-toxic. An algal bloom is an overgrowth of microscopic algae or algae-like bacteria. It’s usually found in fresh and salt waters.
At the same time, the City says the lagoon water is unsafe for recreational use and it will post more signs to warn the public not to drink or swim in the water.
Residents have accused the City of handling the pollution and sewage issues at the lagoon poorly. For years, they have complained about the lagoon’s water quality.
Residents said they suspected the 500-odd dead fish found at the lagoon a few weeks ago were killed by pollution entering the lagoon from the Diep River.
Dr Zahid Badroodien, mayoral committee member for water and sanitation, said his department was investigating the water quality at the lagoon and had created a list of possible pollution sources.
“The directorate is closely monitoring all pollution sources and does regular water-quality sampling and physical inspections of our infrastructure.”
The City had confirmed that the Potsdam sewerage plant was a “small contributor” to the problems in the lagoon, he said, adding that it achieved “high compliance ratings for its treated effluent, which sometimes has nutrients present in the discharge”.
At no point had the Potsdam sewerage plant discharged raw effluent or had any emergency or unauthorised discharges that could have resulted in the algae bloom, he said.
Milnerton resident Trevor Scott said the City had been allowing sewage to be pumped into the lagoon from the Diep River for over a decade.
“They can spin this as badly as they want to, but the fact remains that the City has done a poor job in protecting our waterways. The vlei gets closed every few months because of faulty pump stations leaking sewage. Fish are dying at the lagoon and the number of birdlife has dwindled.
“The detention pond in Milky Way, Phoenix, gets polluted because of the faulty pump station in the area and inadequate sewerage pipe system in Phoenix and Joe Slovo. We can go on and on. The City needs to get their act together.”
Peter Walsh, a committee member of the Milnerton Central Residents’ Association, said it would take more than complaining online about the pollution to change the behaviour of both fellow citizens and the City.
“This problem started more than 15 years ago, and we all saw it coming. Many different NGOs, scientific bodies and experts have been warning us that this would happen. We can take action by using our votes, our community work and representation on committees. Ensuring change is brought about by finding different ways to manage our sewage and reticulation. Engaging with the development community and changing our relationship with our environment. And yes, by exercising our democratic responsibility to hold those accountable,” he said.
Mr Walsh said more residents should get involved in organisations trying to make a difference. People could make a change through beach and community clean-ups, getting involved in their ward committee or simply by pressing ward councillors for answers about the sewage and pollution problems.