City’s sewage destroying marine life
A possible reason behind fish stock collapse
THE City’s seas and its creatures are exposed to a high volume of harmful bacteria, chemicals, pharmaceutical drugs – including antibiotics – cleaning agents as well as female contraceptives.
This is according to Professor Leslie Petrik of the University of the Western Cape’s chemistry department, who tested the water and sea life off the City’s coast.
She said there was a continual release of chemicals with the sewage daily being poured into the ocean, and that could endanger marine organisms. The sewage pollution also had a negative impact on the fertility of the marine organisms.
Petrik said: “This has been ongoing research. The pollution (happens when) disposing the sewage from all the City’s premises – from offices, hospitals and homes.
“All the sewage that is collected from the central city is being discharged at the Green Point marine outfall. All the sewage from Camps Bay is being discharged through the marine outfall in Camps Bay and all the sewage that is collected from Hout Bay is being discharged through a marine outfall in Hout Bay.”
“This means that the sewage is not treated but is just being screened to remove big objects like nappies; everything else goes to the ocean without treatment. That means all the chemicals that we use in our daily lives go with the grey water, faeces and urine that are mixed together and disposed of into the sea,” said Petrik.
She said the research had been an effort to investigate and monitor shore-based pollution at Camps Bay and Green Point, possibly caused by the sewage outfall.
They had recently found several dangerous chemical compounds such as diclofenac, an anti-inflammatory agent, in snoek and other fish bought from Kalk Bay harbour.
She said Dilution of pollution was no solution, especially since these chemical compounds bioaccumulate and move up the food chain.
“If you are discharging sewage to the ocean, you are going to cause a great deal of ecological destruction because of the very problematic chemicals that are in the sewage. The fish stocks are collapsing and this may not be because of overfishing and climate change but because of chemical contaminants, yet nobody talks about the impact that these chemicals have on the fertility of marine organisms. The level of these compounds is not being monitored,” said Petrik.
Water and waste mayco member Xanthea Limberg said: “In all but three of the City’s 20-plus wastewater treatment plants, tertiary treatment methods are employed. The remaining three employ only preliminary treatment and dispose of wastewater via a long pipe extending out to sea, called a long marine outfall. The outfall dilutes the effluent to reduce contaminant concentrations far below what can be achieved with even advanced sewage treatment, and the distance to the coast ensures that bacteria are dispersed or die before they can come into contact with bathers.”
“Long-term scientific monitoring, in terms of the water quality standards, applied to the City’s beaches has confirmed that the City’s outfalls do not pose a significant risk to human health and that the environmental impact is confined to the area within the immediate vicinity of the outfall pipe.
“Incidences of substandard water quality at beaches are mainly attributable to pollution events such as blocked/overflowing sewers, or stormwater ingress – especially after rainfall where pollution from the streets is washed into the stormwater pipes and eventually out to sea. In our decades of testing, it has emerged that low water quality is strongly correlated with rain, especially the first rain of the season,” said Limberg.