Cape Town - The City is warning the public to refrain from swimming in the Disa River in Hout Bay, as it is highly polluted while a Cape Epidemiologist is calling on authorities to heed warnings that the E. coli count was 10 000 organisms per 100ml when the river met the sea.
In an expert analysis, Dr Jo Barnes, an epidemiologist who is a senior lecturer at the Stellenbosch University’s Department of Global Health, Health Systems and Public Health said there have been many instances of documented sewage intrusion into the ocean around the City, but that over recent years the volume and number of such incidents increased substantially.
“Most of the rivers entering the sea are heavily polluted and informal drainage of stormwater contaminated by leaking sewers, overflowing wastewater treatment works, etc. all make their way to the sea,” she explained.
“Also keep in mind that the City has been discharging untreated sewage (only passed through a sieve) into the ocean at several release points for almost a century.
“The volumes of such discharges have also increased.”
Barnes said she and a colleague, Professor Leslie Petrik and her team from the UWC, carried out a study on the size of the impact zone of the intrusions of sewage into the sea.
“Professor Petrik and her team investigated the presence of compounds in pharmaceuticals and personal care products (i.e. shampoos, toothpaste, lotions, etc) in environmental samples in and around the marine environment and I investigated the presence of sewage as represented by the E. coli organisms that occur in gut,” she said.
“This is used as an indicator of sewage in that environment.”
Barnes added the results were disquieting, finding the count of E. coli being high, in the Disa River, especially leading into the sea.
“The chemical compounds in pharmaceuticals and personal care products were present in samples over a far wider area than engineering models usually assume.
“The E. coli counts were very high and increasing as the Disa River running the length of Hout Bay residential area neared the sea.
“A few street blocks from the sea the count was over 8 million organisms per 100 ml water (the SA Water Quality Guidelines for Coastal Marine Waters recreational use is below 500 organisms per 100 ml water). Where the river runs over the beach and mixes with the seawater, the E. coli count is still 10 000 organisms per 100 ml water.”
She said the City was aware of this and called on them to warn the public due to health risks: “This cannot come as a surprise since the City’s own results from 30 April to 3 September 2024 were over the limit on 58% of the sampling occasions.
“When I took the samples, there were no warning signs alerting the public to avoid the contaminated area or any indications of health risks. As far as we are aware, there is no official determination of the ecological damage that such sewage releases do to the ocean itself. Hout Bay is a well-known source of marine products (fish, etc.) for wide distribution.
“Even in other places where signs are erected, they do not contain information on what the risks are and how large the area is that should be avoided.
“That approach transfers the risk decisions onto the general public itself. That is unwise.
“There seems to be inadequate regulatory strategies to limit the risk and very inadequate oversight to enforce the few regulations that do exist.”
The City’s Deputy Mayor and Mayoral Committee Member for Spatial Planning and Environment, Eddie Andrews, said the Disa River was polluted and would be monitoring it, calling on the public to refrain from swimming in it.
“The City currently monitors two locations weekly at Hout Bay Beach, namely the Chapman’s Peak side and Mariners Wharf side,” he explained.
“These are the two sides of the beach that are used for swimming. The results for these two areas are all within the range for acceptable national water quality as per the guidelines.
“The Disa River in Hout Bay is an urban river therefore it is generally highly polluted due to a variety of contributing factors.
“These include, but are not limited to, large amounts of waste from informality where people are not connected to infrastructure, all the storm water that drains into the river, lots of residents in the area (both formal and informal), as well as domestic animals and horses.
“The City has noticed that the coastal water quality declines significantly after a rainfall event because the Disa River flushes into the ocean affecting water quality.
“The water from the river is highly contaminated but thankfully the sea assimilates the water very quickly on the City’s behalf when it enters the sea.
“As a rule of thumb, if there is an urban river, like the Disa River, the public are advised to not swim at a river mouth but to swim at a distance of at least about 150m each side of the river mouth.
“The City will continue to monitor sampling results closely as they come in and alert members of the public if there are any concerns.”
Andrews added the lower Disa River is heavily polluted and the general recommendations to all users were do’t swim in the river; don’t swim where the river joins the sea and use the designated swimming area; Be aware that during and directly after heavy rainfall events water quality declines across the beach area for a short period as the polluted catchment flushes; rainfall also impacts on the low flow diversion that is in place.
Zahid Badroodien, the City’s Mayoral Committee Member for Water and Sanitation (WS) said the City and the Hout Bay Rivers Catchment Forum (HBRCF) have been working together on a comprehensive study, investigating long-term solutions to tackle pollution in waterways in the Disa River.
“From 2021 to 2023, the WS Directorate invested R2 million in the Hout Bay Comprehensive Study to investigate the various sources of pollution, and recommended current, short, medium and long-term interventions to improve the water quality in the Hout Bay catchment,” he detailed.
“Following the study, the Hout Bay Pollution Abatement Strategy and Action Plan (PASAP) was developed. PASAP is a powerful tool used to monitor and track the progress of projects in implementation or planned for the future. It has given the HBRCMF a structure to provide regular input on tasks, actions and projects identified in the PASAP.”
In a community’s response, Peter Flentov, a resident from the Atlantic Seaboard, said they were waiting on a solution.
““The practice of pumping raw sewage into our marine environment is unsustainable. I fear we may reach a tipping point where the system fails catastrophically and we cause permanent harm to the marine environment.
“The City has said that it is committed to finding a solution, but I fear they do not appreciate the urgency of the situation. The City of Cape Town has been kicking the proverbial can down the road for more than a century.
“Each ‘solution’ they have come up with in the past has been a band aid. “Why should we hope that this time will be different?
“The City needs to be more forthcoming with specifics about the options it is considering.”