Residents reminded to avoid contact with Milnerton Lagoon water
12 March 2022
The City of Cape Town is aware that the Milnerton Lagoon is potentially presenting signs of algal bloom. Residents are advised to avoid contact with the water, the same applies to pets.
The City’s Scientific Services Branch has conducted sample testing for algal identification which seeks to quantify the various algal species present. The aim is to identify potential blooms of harmful algae. These are typically blue-green algae aka cyanobacteria which may sometimes produce blooms that contain algal toxins.
It will take a few days for the test results to be released.
The concentration of algae can vary due to factors that can influence their growth, for example sunlight and warmth, availability of nutrients, reduced flows in the river and wind action, even predatory zooplankton and fish that feed on algae. Harmful algal blooms in freshwater are more common in vleis where there is no water flow. In the Milnerton Lagoon, the saltwater near the mouth will increase as the tide pushes, reduce the algal growth and often limit or prevent harmful algal growths.
The City has activated the necessary standard operating procedures in the case of potential algal blooms and all City services are in the process of ensuring rapid attention and action to this matter. To this extent, the City’s Water Pollution Control Unit has initiated an impact assessment that inspects all relevant pump stations, as well as the Potsdam Wastewater Treatment Works.
As a precautionary approach, the City will install additional warning signs to remind residents once again that the Milnerton Lagoon is closed to the public. The Milnerton Lagoon is not suitable for recreational use and signage to inform the public as such has been in place at the lagoon for several years now.
Due to the potential risk of a harmful algal bloom the public is strongly discouraged from coming into contact with the water. The City will confirm whether this is a harmful bloom or not, once the results are available.
At this stage, it is premature to speculate about possible causes.
‘The public is urged to avoid all contact with the water at the lagoon. Dog-walkers should ensure that their pets remain on a leash and prevent them from drinking the water. Parents are encouraged to supervise their children, especially in the vicinity of the lagoon. It is our collective responsibility to exercise caution while the City attends to this matter,’ said the City’s Mayoral Committee Member for Water and Sanitation, Councillor Zahid Badroodien.
The City’s Biodiversity Management Branch will continuously monitor the lagoon to see if there is any impact on wildlife and fish.
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Published by:
City of Cape Town, Media Office
