Questions over City’s coastal water quality data

Fish Hoek has maintained its Blue Flag status, although residents consider it a joke, said Fish Hoek Valley Ratepayers and Residents Association chairman Brian Youngblood in response to the City’s latest coastal water quality report.

Central False Bay is shown to be one of four swimming spots considered to have chronic coastal water quality problems, others are Lagoon Beach (Milnerton), Three Anchor Bay (Sea Point) and Macassar to Gordon’s Bay.

Caroline Marx, of anti-pollution activist group ReThinkTheStink, said even treated effluent from a sewage plant should have less than 1000 E coli cfu/100ml, but, as stated in the report, Simon’s Town Long Beach had 1414 E coli cfu/100ml and the Kom, in Noordhoek had 2420 E coli cfu/100ml and the actual results could be far higher.

Similarly high levels are found in the Know Your Coast report at many beaches including Hout Bay (2420), Silverstroom (7260), Strand Pavilion jetty (1120) and Gordon's Bay (1733), and Ms Marx said they posed possible health risk to users. “How sad in a city famous for its beautiful coastline,” she said.

According to the report, the water quality was “excellent” at Simon’s Town Harbour, Frank’s Beach, Glencairn and Dalebrook and St James tidal pools.

Boulders Beach went from “poor” to “excellent” to “sufficient” over the past three years. Scarborough has been “excellent” since 2019 when it was “sufficient”. Long Beach Kommetjie went from “poor” in 2021 to “sufficient” in 2023, while The Kom was again “poor” from “sufficient” in 2020/21. Noordhoek south beach is “good”, down from “excellent”.

Fish Hoek’s south beach rated “excellent” in 2021 while the central beach has yielded a “poor” result since 2019 with the exception of “sufficient” in 2021.

Clovelly is rated “excellent” from “poor” in 2020/21 albeit with a reading of 579 E coli cfu/100ml.

Mr Youngblood said Fish Hoek Beach readings were worthless because a new sampling point caught the False Bay swirl before it reached two stormwater culverts that had been contaminated with sewage in the past.

According to mayoral committee member for spatial planning and environment Eddie Andrews, this is the third Know Your Coast report.

The latest report covers coastal water quality to September 21, 2023.

The report includes the sampling results from 2018 to 2023, which determined the water quality at recreational beaches, tidal pools, and coastal monitoring points. The key findings come from over 10 000 sample bacterial test sites, twice a month in the surf zone and in tidal swimming pools, along a stretch of 307km coastline from Silwerboomstrand on the Atlantic to Kogel Bay on the east side of False Bay.

The samples are analysed by the City’s scientific services unit and categorised as “excellent”, “good”, “sufficient”, or “poor”, based on a 365-day rolling period.

For most healthy people, water quality that meets acceptable standards, “sufficient” or above, will pose little risk to their health, said the report.

Coastal water quality is assessed by comparing the number of E coli and enterococci bacteria in the water samples to limits set out in the South African Water Quality Guidelines for Coastal Marine Waters. The bacteria serve as indicators of faecal pollution and the potential presence of pathogenic micro-organisms.

The ratings are based on the estimated risk of illness per exposure to swimming for 10 minutes with three head immersions. Less than 2.9% is “excellent”, less than 5% is “good”, less than 8.5% is “sufficient” and more than 8.5% is “poor”.

Apart from the annual Know Your Coast report, the City runs a statistical analysis for each site twice a month.

Dr Alessandro de Maddalena, of the Simon’s Town Shark Museum, said toxic chemicals are passed up the food chain so top predators such as sharks are at higher risk because of the concentration of accumulated toxins. And the effect could be aggravated by the longevity of some species of sharks. The decrease in the number of sharks in False Bay could be partially related to the water pollution, said Dr De Maddalena.

Dr Cleeve Robertson, CEO of the National Sea Rescue Institute, said the City’s data lacked credibility and integrity. Relying solely on E coli measurements gave a limited picture of water quality as sewage could harbour numerous pathogens, he added.

He pointed to discrepancies between the City’s data and the scientific findings of experts such as Professor Leslie Petrik, who leads the Environmental and NanoScience Research Group at UWC, and Dr Jo Barnes, whose primary research focuses on water-related diseases.

Dr Robertson suggested the City was manipulating data to serve its own agenda, which didn't align with the well-being of its citizens.

Mr Andrews said the City needed partnerships with residents. “And for residents to refrain from littering, illegal dumping in our sewers and stormwater mains, and to not dispose of grey water or any other substances in the stormwater mains. Everything that is dumped in our rivers, canals, stormwater mains and streams, from household bin washing, pet waste, household cleaning agents, fats, oils and grease, eventually finds its way into the sea,” he said.

View the report at capetown.gov.za