E coli levels in Rietvlei are more than 30 times what is considered safe, according to a City sampling.
The vlei in the Table Bay Nature Reserve remains closed for all recreational water activities, after high levels of pollution were detected (“City closes Rietvlei after pollution spike,” Tabletalk, June 30).
Xanthea Limberg, mayoral committee member for water and waste, said the vlei would stay closed until testing confirmed the water was safe.
In response to questions from Tabletalk, Ms Limberg said the City was investigating what might have caused the pollution problem.
However, she added, that due to very heavy rains the vlei had broken its banks and flooded the pump station at the Potsdam Wastewater Treatment Works dry well. All the pumps and motors had been swamped and damaged.
A team had been sent on Friday July 2 to assess the damage and had fixed one of the pumps, she said.
“Another pump, however, was damaged and has been sent for repairs. It is hoped that this second pump can be installed and fixed by the end of this week,” she said.
E coli is measured in cfu (colony forming units) and acceptable levels, according to Ms Limberg, should be less than 33 cfu per 100ml. The last reading at Rietvlei was 1000 cfu per 100ml.
The water was not toxic but it could cause gastrointestinal problems in those coming into contact with it, she said.
A short-term solution would be to wait for the E coli to break down and become diluted.
“It cannot be removed from an open environmental water body. Closing the vlei is a temporary solution,” she said.
E coli contamination could be caused by a failure in the sewerage system or stormwater run-off during the rainy season, she said.
“This is because any pollution from the inland urban environment is washed off the roads, down the stormwater network, and out into the receiving water bodies.”