City to probe lagoon fish deaths

About 500 dead fish were found in the Milnerton Lagoon last week. Residents suspect pollution is to blame.

The City is investigating after hundreds of dead fish were found in the Milnerton Lagoon.

Following reports from residents, about 500 fish, mostly juvenile mullet and southern mullet, were cleared from the lagoon on Thursday afternoon, according to a City statement.

“The fish were removed for disposal by a team from the Table Bay Nature Reserve on the same day. The City has initiated an investigation to determine the possible causes of the fish die-off, including an analysis of the water quality. In the meantime, we continue to monitor the situation,” said the statement.

Residents suspect sewage spills are to blame for the dead fish and a stench that has hung over the area for several months.

Caroline Marx, a member of the Milnerton Central Residents’ Association (MCRA), said they were waiting to hear from the City what had caused the fish deaths.

“But high pollution levels in the river and lagoon are suspected. The sources of pollution need to be addressed and stopped in order for a healthy ecosystem,” she said.

“The fish deaths are just a symptom of a much bigger problem. The smell comes and goes depending on the weather, wind, tide and recent pollution. Recently it had sometimes smelt very badly of raw sewage. Near the Erica Road stormwater outlet, opposite the high school, the smell is very constant.”

In a statement on Sunday March 6, the MCRA said it noted concerns about the “continued and frequent discharges of large volumes of poorly treated effluent from Potsdam Wastewater Treatment Plant into the Diep River over the past months”.

The Erica Road stormwater outlet continued to discharge significant volumes of highly polluted water into the lagoon, the association said.

“Such discharges have had a massive detrimental impact on the ecosystem of the river with the virtual disappearance of sand prawns and other aquatic life. The fish biopsy results are awaited, but it would be disingenuous of the City of Cape Town to claim fish deaths are unexpected,” said the statement.

Mary Norman, who has lived in Milnerton for more than 20 years, said it had become unbearable to live there because of the smell.

“It has become way too much over the last few years. I have to stay with my doors and windows closed even on extremely hot days. This is not what I signed up for when I bought my place here. I am thinking of selling and moving somewhere else. But who is going to even want to buy property this side? Our property values are dropping because of this. The City needs to do something.”

Ms Marx said the results of tests done on the effluent being discharged by the Potsdam sewage plant should be made public.

“This needs to include chlorine and COD (chemical oxygen demand) levels as heavy dosing of chlorine will reduce the E Coli levels. However, the effluent may still cause major damage to the ecosystem and by overloading the system with nutrients cause toxic algal blooms,” she said.

City workers removed hundreds of dead fish from the lagoon last week.

Ward councillor Fabian Ah-Sing said the City was still investigating and the water-quality test results were not available by the time of publication. However, Mr Ah-Sing said a feedback meeting would be held today, Wednesday March 9.

“Five hundred dead fish is quite a lot, and we need to find out what the cause is. I know that last time something like this happened, it was linked to pollution,” he said.

“While we will still have our meeting on Wednesday, I can confirm that there are interventions planned for the Erica Road outlet. A diversion system is going to be put in place quite soon. Currently, the outlet pumps for seven hours a day, but I am of the opinion that we should aim for it to pump 24/7 so that we can ease some of the sewage spills.”