Azra Hoosen | ah@radioislam.co.za
8 January 2025 | 09:15 CAT
3 min read

The Hennops River in Gauteng has turned an alarming shade of green, a visual warning of toxic algal blooms linked to severe pollution. Experts and environmental activists attribute this crisis to years of sewage leaks, agricultural runoff, and failing infrastructure.

Willem Snyman, head of the Fountain River Environmental Sanctuary Hennops (Fresh), explains that while algal blooms have been a recurring issue upstream at Rietvlei Dam, this is the first time such extreme pollution has affected the Hennops River. The toxic algae, fueled by high levels of pollutants, produce microcystin—a hazardous toxin posing serious health risks to both humans and animals.

Snyman explained that the Hennops River runs straight through Centurion and supports several nature reserves, including the Rietvlei Dam, Crocodile River Reserve, and Swartkoppies Nature Reserve. Many farmers in areas like Wierda Park and Laudium still rely on this water for irrigation. “The problem with this cyanobacteria is that it’s a very small toxin, and it’s very potent. So it can bio-accumulate in plants and if you irrigate with it. So it is actually very dangerous, and it seems to affect the liver and kidneys,” he said.

He noted there was a death at the end of last year that appeared to be linked to cyanobacteria exposure. Someone accidentally consumed a small amount of the contaminated water in tea, and the symptoms pointed to the toxin. Additionally, a vegetable farmer working near the river was affected. “So one can see that these things are very dangerous,” he added.

Snyman believes infrastructure issues are a primary cause of this crisis, particularly upstream of Rietvlei Dam. He explained that Cyanobacteria blooms are often linked to stagnant water, like you find in dams. Upstream, in Ekurhuleni, there’s a wastewater treatment plant that contributes to the problem, along with significant runoff from informal settlements along the Swartspruit. Currently, Rietvlei Dam has some of the highest cyanobacteria levels in Gauteng, which is alarming. This dam is fed by strong natural fountains, so the water should be crystal clear. Instead, it’s dangerously toxic, and many people use this water for drinking.

The real challenge is that cyanobacteria are so tiny they essentially become part of the water molecule, making it extremely difficult to remove them during treatment. “This really just adds to the toxic load already in the river, which is already very polluted,” he said.

He noted that studies from years back have already shown high levels of endocrine disruptors, heavy metals, and other pollutants in the smaller organisms at Rietvlei Dam. Despite the urgency, it seems there’s a reluctance to acknowledge the severity of the issue. “But, you know, I think it’s almost like a point of pride that they don’t really want to admit that something is wrong. So we are still hoping,” he said.

When asked about immediate measures to address the effects of cyanobacteria blooms on local communities, Snyman explained that there are few active interventions. There was a system called a ‘cyanobac beater’ used to manage blooms by pushing the bacteria to the sides of the dam, but it had been out of operation for some time. “I’ve heard it’s recently been repaired, which could help. However, it might pose additional risks to animals drinking the concentrated water along the edges, especially given past reports of large animal deaths in regions like Botswana,” he said.

He warns that the blooms, combined with irrigation from polluted waters near sewage plants, create a serious health risk. Crops irrigated with this water are sold in both informal settlements and formal markets, posing a potential threat to food safety. The toxins also flow downstream, fueling further blooms and contaminating water sources used for agriculture.

Snyman highlighted that people often dump rubbish and sewage into the streams feeding the river, not realising the impact on those downstream. This is compounded by municipalities failing to manage waste and provide proper sanitation, especially in informal settlements that have sprung up along the riverbanks.

To mitigate the crisis, he believes education is crucial, if communities understand the risks, they might take steps to reduce pollution. But this must be paired with better municipal services to prevent the cycle of contamination.

He expressed hope that efforts to address these issues will succeed before the situation worsens further.

LISTEN to the full interview with Ml Habib Bobat and Willem Snyman, head of the Fountain River Environmental Sanctuary Hennops (Fresh), here.