Mining pollution kills fish, threatens public health in Maphisa’s Mazayi river

A recent cyanide spill in Mazayi River in Maphisa in Matobo District has sparked an outcry over mining companies’ environmental negligence and failure to benefit local communities.

The sight of hundreds of dead fish floating in the river in April last month sent shockwaves through Maphisa. 

For the communities that depend on this river, the primary water source for thousands in Matobo District, this was more than an ecological disaster; it was a chilling warning about the toxic cost of unchecked mining operations.

Locals suspected the contamination came from Cyanide, a highly toxic chemical used in gold processing, believed to have been washed into the river from a mining waste dump following heavy rains.

Mazayi river flows dangerously close to Antelope Dam, the primary water source for Maphisa town, nearby villages, ARDA plantations, and livestock. 

Communities as far as Lingwe, Tshelanyemba, Sun-Yet-Sen and Tshatshe rely on the river system for drinking water and farming, now potentially threatened by this toxic spill.

Despite claims by the Environmental Management Agency (EMA) that Mazayi River’s water is now clear from contamination, water quality results from an independent test have revealed dangerously high levels of contamination, raising serious public health concerns for residents who rely on the river for use and watering their animals.

Water quality results from Mazayi River in Maphisa, tested on May 6, 2025, by a Bulawayo-based laboratory, EcoVision, commissioned by CITE, confirmed dangerously high contamination levels, raising urgent public health concerns for residents who rely on the river. 

The water sample showed excessive calcium hardness, total dissolved solids, high salinity (512 ppm), and conductivity (1030 µs/cm), all well above World Health Organisation (WHO) limits.

EcoVision’s CEO and water engineer noted that elevated hardness can damage appliances and pipes, while high salinity and conductivity make the water unsuitable for consumption, especially for people with hypertension or kidney problems. 

Turbidity was also high, indicating suspended particles, and industrial pollutants and heavy metals were present, which pose long-term health risks such as cancer and nervous system damage.

“Heavy metals, even in trace amounts, can accumulate in the body over time, potentially resulting in serious health problems like cancers, skin disorders and nervous system damage,” warned the engineer.

Although the pH value (7.35) fell within safe limits, the water engineer stressed that the overall results show the water is unsafe for any domestic use unless thoroughly treated. 

“The water will need to go through treatment to remove the harmful compounds in the water,” said the engineer.

However, EMA Matabeleland South Provincial Manager, Decent Ndlovu, questioned the validity and interpretation of independent laboratory results for water samples taken from Mazayi River in Maphisa, suggesting they were analysed using inappropriate standards.

In a detailed explanation, Ndlovu said the test results applied WHO potable drinking water standards, which are not suitable for untreated surface water from a natural pool or stream (isiziba). 

“These standards apply to water from the tap, ready for human consumption, not water collected from an open pool where animals urinate, and people wash clothes,” he stated.

He criticised the lab for failing to clarify the source of the water and for not identifying which heavy metals were present.

“Yes, the results talk about heavy metals and industrial pollutants, but they don’t tell us which ones, nor do they quantify their presence or toxicity levels,” Ndlovu said, noting that heavy metals naturally occur in most environments, including rural streams.

Ndlovu further noted that turbidity and discolouration are to be expected in untreated surface water.

“The lab says the water is clear, yet you see visibly that the water is murky. That’s common in pools where livestock drink,” he said, adding that the brown colour in water might indicate rust or natural metal deposits, but not necessarily industrial contamination.

He raised concern that using potable water standards to assess river water was misleading.

“If you assess such surface water using drinking water standards, almost all indicators will appear in the danger zone, yet no one drinks directly from such sources without treatment,” Ndlovu explained.

On Cyanide detection, Ndlovu maintained that EMA had initially detected cyanide, but follow-up testing days later showed no traces. 

“Cyanide quickly degrades when exposed to sunlight. The pool now has live fish, proving there’s no lingering contamination,” he stated.

Regarding possible sources of contamination, Ndlovu said EMA believes it may have come from washing of used cyanide containers in the river, rather than direct discharge from a mining company like Nevada 24.

He pointed out that although Nevada 24 had been forced to close its old dump site, there was no scientific link between the mine and the fish deaths observed.

Ndlovu added that there is need for better sampling procedures, saying water meant for chemical testing must be collected in disinfected containers, analysed within 24 hours, and ideally handled by trained technicians.

“You can’t just collect water in any bottle and expect accurate results,” he noted.

He concluded by recommending that communities and journalists work closely with accredited laboratories and technical experts when testing environmental water.

“The lab used wrong standards and failed to provide critical context, making the results unnecessarily alarming,” Ndlovu said.

Despite these assertions, local authorities, villagers and traditional leaders now point fingers at the unregulated mining activities in Matobo District, accusing them of endangering human and environmental health while contributing nothing to the development of the communities from which they extract gold.

Councillor Nqobizitha Ngwenya of Ward 19, which covers Maphisa, confirmed that cyanide was a key suspect in the contamination.

“Tests confirmed traces of cyanide in the stream,” Ngwenya told CITE, noting the source remains contested. 

“EMA called the manager of Navada24, the one which mostly uses cyanide to ask what they do with their empty cyanide containers. The mine manager said he throws them away but we see the containers sold here at Maphisa, which means some collect them and wash them but we don’t know where they wash these containers.”

Ngwenya said the current evidence points to a failure in safe disposal practices by mines.

“Whether it was the slime spilling or the containers being washed, it all comes back to poor management by Nevada 24,” he said.

Beyond the contamination, Ngwenya expressed strong criticism of the mining sector’s overall conduct in Matobo.

“We are not benefiting anything from these mining companies,” he said.

“They come, mine, and go. Even our hospital here doesn’t have backup power. Look at our hospital here, it doesn’t have backup power or lighting, at night the staff use candles. The mining companies can’t even offer to put up  light bulbs as an appreciation. You then realise these mines are run by people who are not from the area.”

Ngwenya claimed most of the mines in Matobo do not pay rates to the Matobo Rural District Council.

“Only about two companies pay. The rest contribute nothing  and this may be due to the government’s relaxed approach,” he noted. 

“We are 33 councillors and across the political divide, we all agree that the miners must all bring and leave at least something to the district. I have not met any councillor who agrees with what the mining companies are currently doing. As councillors we agree that the mining companies are letting us down.”

Ngwenya added that their position as councillors was a development approach.

“We all agree that they should engage the council and pay rates so that council offers services. We are the one maintaining those roads and providing services. The council cannot provide those services for free, so as councillors we are united, looking forward to the development of Matobo,” he said.

“There is nothing untoward about this because Matobo comes first before anything else.”

Ngwenya further said that the community now wants miners to be held to stricter environmental and social standards.

“Yes, we want investment, but not at the cost of our water, our livestock and our children’s health,” he said. 

Johnson Gumede, a village head under Chief Fuyane, said residents first noticed the problem in early April when a shoal of dead fish was seen floating in the Mazayi River, some caught under the bridge near Maphisa. 

Crows were reportedly seen feeding on the dead fish, while some children tried to cook and sell them before warnings were issued. 

“Children were seen collecting the fish, unaware of the potential danger. We had to send urgent warnings telling people not to eat the dead fish,” he said.

Mavuso Tshabalala, a resident of Mafuyana suburb said they heard “from ZINWA and EMA that traces of cyanide were found in the water.”

He claimed this was “poison used by mining companies during gold extraction. That’s what killed the fish.”

Tshabalala said the river’s contamination affected a large swath of Matobo: “Ward 22, Ward 19, Ward 20, all the way to Ward 7 Tshelanyemba and Ward 6 Sigangatsha, all drink from this river. Even livestock that drink from here are now at risk.”

Suspicion fell on Nevada 24, a gold processing operation nearby, which uses cyanide to extract gold from crushed rocks (slime).

According to locals, rains may have breached containment barriers and washed the cyanide-laced waste into the river.

“We saw the slime buildup and the liquid trail that led directly to the river,” said the village head. “We followed the signs from the mine site all the way to the bridge where the fish were dying.”

Despite EMA collecting water samples for testing, residents say they had not received any formal feedback. 

“It’s been over two weeks and there is no report, no explanation,” said Tshabalala, expressing frustration over the lack of communication from both EMA and ZINWA.

“People are sceptical of even drinking tap water. We don’t know if it’s safe or if we’re drinking slow poison.”

Residents are now demanding a public health response to the potential poisoning.

“Authorities should have come to tell us what to do, whether to boil the water or avoid it altogether,” Tshabalala adding, that was “just poor governance.”

Meanwhile, in the absence of swift action from authorities, residents are mobilising to clean their own water. Councillor Ngwenya said they were planning to form a steering committee to spearhead water testing and contamination response.

“After the meeting, we will appoint people to be part of the steering committee to focus on a disaster management system as residents because we foresee a lot of disasters coming. It will be good that these processes are managed in a professional manner. Some experts told us there are chemicals that can neutralise cyanide,” he said. 

“We’ll involve EMA in that process. We’re mobilising resources from residents and well-wishers but residents have to be at the forefront because they have to own the process of making sure their environment is clean.”

The committee is expected to regularly monitor water quality, especially during rains when runoff from mines could reintroduce pollutants into the river.

This is not the first time Matobo communities have faced environmental disasters caused by mining.

Ngwenya said last year, operations at Nyamazana Plant were halted after villagers protested the company’s reckless disposal of chemical waste. 

A parliamentary portfolio committee intervened to stop operations.

Yet villagers say lessons were not learned.

“We hear that four to five kilogrammes of gold is processed in that area monthly,  as a community of Matobo we are benefitting nothing except having the fish killed and the environment including damage which comes from their trucks carrying the chemicals which destroy the road,” Tshabalala said.

“It’s painful that some people are benefiting from our resources yet we are only left with holes and chemicals. We hear authorities saying our economy is backed by gold but communities where that gold comes from have nothing.  We don’t know where the gold is going.”

“Roads are dead, school children have no proper school infrastructure to sit on, there are no computers, there are no classroom blocks because people who are running means of production are not from the local area and do not care about development of the area. They care about making their money.”

The councillor called for stronger government oversight and said Parliament must question the environmental assessments submitted by mining firms operating in the area.

“Did they ever have proper mitigation plans? Did they consult communities? These are the questions we are asking,” he said.

Ngwenya also called on political leaders to speak up.

“This is where our MPs and senators must come in and represent us. We can’t keep quiet while our water is poisoned, and our people are left in the dark.”

Maphisa Residents Association is expected to hold a public meeting soon and may petition Parliament for urgent intervention.