Gauteng river turns toxic

The 100 km-long Klip River in Gauteng, a vital water source feeding into the Vaal River System, has reached critical pollution levels.

The pollution levels are so high that they seriously threaten the communities and ecosystems that depend on it.

A recent environmental assessment study by researchers from the University of Johannesburg (UJ) has exposed the alarming presence of polycyclic aromatic hydrocarbons (PAHs) in the river’s sediments.

These are organic chemicals linked to many health problems, including organ damage, developmental disorders, and cancer.

The Klip River flows generally south, turning east along the southern edge of Soweto. It passes through Lenasia, Henley-on-Klip, and Meyerton before joining the Vaal River System.

The water resource serves the surrounding communities, sustaining families, livestock, and local ecosystems. It is also used for religious practices like baptisms.

“But beneath its flowing surface lies a hidden danger: cancer-causing organic pollutants accumulating at levels high enough to potentially harm human health, animals, and aquatic life,” said UJ’s Department of Chemical Sciences researchers.

Led by Samuel Makobe, Dr Mathapelo Seopela, and Prof Abayneh Ambushe, the study analysed river sediments from nine sites along the Klip River, in both wet and dry seasons.

Their findings, published in Environmental Monitoring and Assessment, reveal:

• Total concentrations of PAHs in river sediments reached up to 7.41 mg/kg—far exceeding environmental safety thresholds.
• High-risk toxins peak in dry seasons when water levels are lower and increasing the exposure risks as communities rely more heavily on the river.
• Zebrafish embryos exposed to sediments suffered severe malformations, delayed hatching, and 80% mortality, signalling dire risks for aquatic life and human health.

Professor Ambushe said that PAHs are well-known for their persistence and harmful effects. They mainly come from sources such as oil spills, industrial runoff, and leaking fuel tanks.

Additionally, PAHs are generated through the combustion of coal, waste, and biomass, which is frequently seen in urban and informal communities, particularly near bodies of water.

“These toxins don’t just vanish… they linger in sediments, enter the food chain, and accumulate in humans and animals over time,” said Ambushe. “This is a public health crisis in slow motion.”

The UJ team used percentage composition and diagnostic ratio analysis to identify that over 70% of PAHs came from these sources.

“The problem is systemic urbanisation, inadequate waste management, and historical pollution have turned the Klip River into a chemical reservoir,” said Seopela.

Seopela emphasised that the Klip River supplies water to the Vaal River System, a vital source for millions in and around Gauteng.

“Contaminated sediments threaten communities using river water for drinking, laundry, or irrigation; livestock grazing along banks, risking toxin transfer to meat and dairy; and biodiversity, with PAHs disrupting fish reproduction and amphibian survival,” said Seopela.

A toxicity investigation utilising the zebrafish embryo development test found that heart abnormalities and spinal deformities manifested within just a few days of exposure.

The UJ experts explained that zebrafish possess roughly 70% of the same genetic and physiological characteristics as humans.

These results strongly imply that individuals in human populations exposed to environments tainted with PAHs may experience comparable developmental and cardiovascular issues.

“If these toxins can devastate aquatic life so quickly, imagine their long-term impact on humans,” said Makobe.

“The study isn’t just exposing the Klip River’s pollution crisis, but the research is leading the charge for solutions,” added Ambushe.

“By integrating advanced chemical analysis with bioassays, the research team pinpoints seasonal pollution hotspots for targeted cleanup, advocating for stricter industrial regulations, and empowering communities with data to demand safer water policies.”

Seopela told the SABC that “it would be good for the Department of Water Affairs and the Department of Environment to start looking at how we are doing with environmental monitoring.”

Despite numerous calls for urgent intervention, the Klip River continues to face severe pollution from mining activities, industrial as well as urban runoff, and failing wastewater treatment.

Reactions to the study

Executive manager of water rights advocacy group WaterCAN, Dr Ferrial Adam told BusinessTech that the findings of the research “are shocking, it is unfortunately not unexpected.”

Just last year, desperate attempts to use a private company to retrieve the body of a seven-year-old boy who drowned in the Klip River hit a brick wall after police barred private divers from entering the “contaminated” water.

In July 2023, WaterCAN opened a criminal complaint against the City of Johannesburg and its former managers over the ongoing pollution of the Klip River by two leaking wastewater treatment works (WWTW).

The problems include Goudkoppies WWTW in Riversdale and the nearby Bushkoppies WWTW in Eldorado Park, which leak untreated sewage into the water sources.

Adam said “frustratingly, the wheels of justice turn very very slowly in the country.” It is soon to be investigated.” Investigations still need to take place.

“Unfortunately, this is just one example of the many dangerously polluted water sources across the country,” she added.

In August 2022, the national Department of Water and Sanitation (DWS) issued a directive to the City of Johannesburg, ordering the City to clean up the river. However, the pollution persists. 

Water expert and environmental advisor Dr Anthony Turton recently told BusinessTech, “The simple truth is that WWTWs are slowly rendering the country’s drinking water unusable.”

“Without sounding dramatic, South Africa is slowly committing ecocide – national suicide by poisoning its own drinking and crop production water,” said Turton.

He said South Africa mirrors a global crisis, where a growing population is dependent on a diminishing freshwater supply, with pollution exacerbating the problem.

However, he notes that South Africa is far from mitigation efforts right now, as well as falling behind in key technological advancements in the sector.

Turton said South Africa’s policies are mostly fine but unenforced.

Two key issues exacerbate the crisis:

• The outdated drinking water standard fails to address toxins like cyanotoxins, PFAS, and endocrine disruptors;
• The government’s “Three D’s” approach to the crisis—Deny, Deflect, and Demonise—has eroded public trust, with political parties confusing the public by downplaying dangers like that of blue-green algae.

Turton said the “single most important step is to stand together in holding elected officials accountable, arguing that non-accountability has caused the collapse of the water systems.”

The DWS was reached out to for comment, but did not respond by the time of publication. Responses will be added if received.

The Gauteng Department of Environment was also reached out to, but calls were unanswered.