Harare City Council has been discharging raw sewage into the Mukuvisi River, which flows into Lake Chivero, the city's main water source, for the past two weeks, The Herald can reveal.
This has created serious health and environmental hazards, resulting in Zimparks banning all fishing activities at Lake Chivero, where thousands of fish have died, alongside animals including four rhinos and three zebras.
The pollution, primarily from raw sewage, has caused a surge in cyanobacteria, posing health risks to both humans and wildlife.
The Herald team traced the sewage discharge back to the Crowborough Sewerage Works, one of Harare's five treatment plants, which has a capacity of 54 million litres per day.
Observations revealed that council was directly pumping sewage into Mukuvisi River.
Along the sewer line, multiple burst pipes were found leaking sewage into the river and surrounding fields, where farmers depend on the flow.
Despite having replacement pipes available, council is yet to install them.
The area is poorly secured, making it easy for our crew to access without encountering security personnel.
Residents, speaking anonymously, expressed their frustration.
"The calamity at Lake Chivero stems from here. Bursting pipes from Kuwadzana should supply Crowborough for treatment, but instead, the council has allowed sewage to flow directly into the Mukuvisi River," one resident said.
Another resident noted that while attempts were made to block the sewage flow, the situation remained critical.
"The sewage is still pouring into the river. We need urgent intervention. This is the same water we drink."
Experts have said the rise in cyanobacteria due to pollution -- primarily from raw sewage -- poses health risks to both humans and animals alike.
"The situation at Lake Chivero is indeed concerning and raises several important ecological and environmental questions. Cyanobacteria, or blue-green algae, can produce toxins that are harmful to various wildlife, including large mammals like rhinos and other species. If Zimparks attributes the deaths to cyanobacterial poisoning, it is plausible that this could affect both aquatic and terrestrial animals,"said an environmental expert.
He stressed that the toxins in Lake Chivero can enter the food chain; for example, animals might consume contaminated water or prey on fish that have been affected.
"While cyanobacteria poisoning is a significant concern, it's important to consider other possible factors, like pollution, the mention of raw sewage entering the lake suggests that pollution could be contributing to the overall health of the ecosystem, impacting both water quality and the health of wildlife."
He added that diseases could affect wildlife populations, especially if they are already stressed by environmental factors, adding that changes in the ecosystem, whether from human activity or climate change, could weaken animal populations, making them more susceptible to illness.
The expert said eutrophication, a condition that is often caused by nutrient runoff (like sewage), can lead to oxygen depletion, resulting in fish deaths.
Environment, Climate and Wildlife Minister Sithembiso Nyoni yesterday led a Government team to Lake Chivero and said measures are being put in place to protect the public.
"Our people are at risk not because of any external organisation, there are some people who are fishing in this lake, there are some people that are combining dead fish with live fish and then those fish are being sold to our people who may not die immediately but they may now start developing cancers. I came here because our animals, livestock are dying, there are people whose cattle, goats are dying, so that is an economy that is being shaken. We are responsible for the cleanliness, of the atmosphere and of the water," said Minister Nyoni.
Following the deaths of fish Zimparks announced a fishing ban at Lake Chivero, stating, "We have suspended all fishing activities with immediate effect. We are conducting investigations with other Government departments to assess the safety of the fish for human consumption."
At yesterday's full council meeting, Harare Mayor Jacob Mafume said the trouble ridden council has been failing to reach its sewage treatment capacity.
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"We need resources for water treatment and expertise to effectively address this issue," he said, adding that the technical team is collaborating with experts from National Parks to investigate pollution levels.
Mr Reuben Akili, director of the Combined Harare Residents Association (CHRA), condemned the pollution of Lake Chivero.
"The pollution levels have reached alarming heights, threatening human health and wildlife," he said, warning that reported fatalities among animals and fish are just early indicators of a broader ecological crisis.
Environmental advocates, including the Harare Wetlands Trust (HWT), issued a 48-hour ultimatum to the City of Harare and other relevant authorities to tackle the severe contamination of Lake Chivero. HWT emphasised the need to uphol constitutional rights of citizens to a safe and healthy environment, urging immediate cessation of sewage discharges.
The body also warned of potential legal action if the demands are not met.
