Sewage crisis means Vaal water lettuce is here to stay
Temporary interventions by the government to stop the rapid spread of alien invasive plants such as water lettuce on the Vaal River are not enough to save South Africa’s rivers.
This is according to scientist Anthony Turton, a water expert at the Centre for Environmental Management at the University of the Free State, who said the continued recurrence of water lettuce in South African rivers was caused by sewage spills resulting from infrastructure breakdowns and upstream pollution.
Last week, AfriForum and the Freedom Front Plus in the region accused the water and sanitation department and the department of forestry, fisheries and environmental affairs of neglecting residents in the Sebokeng area, who are removing the invasive plant to halt the spread of the water lettuce.
To explain the inadequate treatment solutions by the government, Turton likened the government’s interventions to treating a brain tumour with painkillers.
“The interventions are the same as a patient who goes to a doctor looking for a solution to a persistent headache. Instead of the doctor putting the patient under an MRI to check for the root cause, they send the patient home with Panados.”
“[T]he Panados help the symptoms of the headache go away for a short period, but doesn’t stop the growing tumour in the brain, which is the same as manually removing these plants without solving the sewage crisis we have in the country,” he said.
He added that the sewage pollution in the Vaal Dam made it conducive for these plants to grow. “This is because the high levels of nutrients found in sewage systems feed this plant and cause rapid growth.”
What is water lettuce?
Water lettuce (Pistia stratiotes) is the world’s fastest-growing aquatic weed, and has already suffocated water bodies across South Africa.
It is a floating plant with rosettes of leaves that resemble lettuce and is native to tropical and subtropical regions in South America and is often used ornamentally in ponds and aquariums.
Water lettuce has already made its bed in the Vaal River, forcing people in the Sebokeng area to remove the stems manually from the river.
Turton said that if left untreated, the plant covers the entire river, blocking sunlight from reaching the water.
He added that excessive growth of water lettuce can contribute to water quality issues because when large mats of water lettuce decay, they can release organic matter, leading to nutrient enrichment and potentially causing algae blooms.
The plant has also been seen in KwaZulu-Natal, Eastern Cape and Mpumalanga, including the Kruger National Park, thriving in nutrient-enriched, slow-moving waters.
Solutions
Turton said the only solution to the problem lies in resolving the sewage situation by placing experienced people in positions to deal with issues.
“The Vaal River, for example, supplies most of Johannesburg through Rand Water, but the broken infrastructure makes it almost impossible to preserve clean drinking water. The treatment requirements for nutrients in these rivers are inadequate, therefore, these alien invasion plants will continue to grow,” he said.
The Vaal River System is a water source for 19 million people in Gauteng, Northern Cape, the Free State and the Northern Cape through treatment systems owned by Rand Water, according to the department of water and sanitation.
The growth of alien water plants comes despite NGOs in the region winning a case against Water and Sanitation Minister Senzo Mchunu to stop the sewage pollution of the Vaal River and its tributaries.
Turton said: “Put technically competent people in authority and then hold them accountable. How can 50% of the drinking water we pump into municipalities get lost before it gets to the end user? It is incompetent management of these services that leads to the challenges in the water sector.”
The Blue Drop Report released by the department in November showed that it is not “microbiologically safe to drink the water in about half of South Africa’s water systems” and that “57% of municipalities don’t notify people in the event of water quality being compromised or not monitored”.
AfriForum’s regional head for the central region, Jaco Grobbelaar, said the civil rights group had taken the initiative to manually remove more than 1 623 tonnes of water lettuce from the Vaal after the two departments ignored their calls to have the invasive species removed.
“We as a community are actually now doing work that is the government’s responsibility. It is clear to us that the government does not care about our scarce resource and would rather spend time having meetings than actually doing something about the problem. We can’t just sit in meetings while the problems outside worsen,” Grobbelaar said in a statement.
Environment department spokesperson Peter Mbelengwa said the department is working closely with the water and sanitation department to resolve the problem.
Last year, the environment department launched a R2.6 billion working water programme aimed at protecting and controlling invasive alien plants over 1.2 million hectares in the country. The programme is to run for five years.
The water and sanitation department had not responded to a request for comment at the time of publication.