Cape Town - The reopening of Rietvlei as a result of pressure from the Milnerton Aquatic Club, which conducted its own independent water quality testing at the wetland, has renewed calls for the scrapping of restrictions on independent water testing.
It also raised questions about the City’s testing equipment and testing sites used, including scientists’ ethics and public availability of water quality tests.
The testing of any water body within a nature reserve without written authorisation is prohibited by the City.
The City recently reopened Rietvlei following three independent water quality tests conducted by the Milnerton Aquatic Club which varied from those it conducted.
UCT Environmental Humanities South centre director Professor Lesley Green said it was concerning that the findings of the scientific service were again questioned.
“As a city, we must be able to rely on good science. We need Scientific Services to provide us with reliable information. We are in the era of Covid-19 and when you destroy public trust in science, you destroy the best of democratic agreements,” she said.
Green said the City’s scientific services were either incompetent, suffering equipment failure, or political interference.
“A full independent inquiry as to what has gone wrong at the City's scientific services is needed, together with the change in the by-laws on independent testing at the nature reserves,” she said.
One of the Save the Zandvlei petitioners, Charles Whaley, said since the Rietvlei results appeared to show that City’s testing system was inadequate, there was a need to check whether the same applied to Zandvlei.
“We haven’t had results for the last couple of months and although we heard that results were improved but not low enough for the vlei’s reopening. Tests are expensive and proper scientific tests would be beyond the budget of individuals.
“It would only be feasible if an organisation like the canoe club or the Marina da Gama Residents Association had the funds to do their own tests. But it would be interesting to know if independently conducted tests came up with the same results as the City’s in Zandvlei,” Whaley said.
Marina Da Gama resident Mike Ryder said given wide variations in past e-coli results for Zandvlei, it was not surprising that the City test results elsewhere had been called into question.
Ryder said testing should be performed by an independent certified laboratory and the City must encourage independent sampling and testing.
Water and Sanitation mayco member Zahid Badroodien said the City’s Scientific Services Branch is an accredited laboratory where samples are analysed in parallel with a number of strict quality control processes to ensure validity of results.
He said these quality control processes ensure that there is no contamination that occurs during the processing of the samples.
“The first point is to check the integrity of the samples when they are received in the lab (temperature checks, correct sample bottles). This is followed by the preparation of Analytical Quality Controls (AQCs) such as positive controls and negative controls.
“The laboratory participates in the National proficiency-testing scheme on a regular basis, and all results have passed,” he said.
Badroodien said the City would, in coming days, undertake further water quality testing at Zandvlei and Zeekoevlei.
Deputy Mayor and Spatial Planning and Environment mayco member Eddie Andrews said the City has not received any applications for water testing at Zeekoevlei or Zandvlei.