From Mboneko Munyaga in Mwanza.
Once a vibrant symbol of life, Lake Victoria is now one of the world’s most polluted freshwater bodies – its future hanging by a thread as fish stocks collapse, pollution surges and the millions it once nurtured and nourished, face growing uncertainty.
Lake Victoria, or Nyanza, is East Africa’s largest lake and the second-largest globally. For decades, it has sustained communities across Tanzania, Kenya and Uganda, offering water, food and economic opportunity. But today, its once-clear waters have turned a murky waste, its fish disappearing and its role as a regional lifeline coming under serious threat.
Along its shores, scenes of despair are becoming all too common. Fishermen push out canoes into the slimy waters, hoping for a good catch – but return with little or nothing. “We used to catch enough to feed our families and sell at the market,” says a fisherman from Sengerema who requested anonymity. “Now we go out all night and come back with barely anything.”
The small, bony cichlids – furu – that once filled local plates, they too have become scarce, now eaten by everyone, not just the poor. Over the past few decades, ecological studies supported by the Lake Victoria Fisheries Organisation have documented a drastic collapse in native fish biodiversity. Once-dominant haplochromine cichlids have declined by over 90 per cent, with many species now critically endangered or extinct.
The introduction of the Nile Perch (sangara) in the 1950s initially boosted commercial fishing. However, their dominance led to the disappearance of many smaller native species, including the favourite Nile Tilapia (sato) and triggered a chain of ecological disruption. While the Nile Perch boom created a thriving fish export industry – especially around Mwanza – it also made fish unaffordable for many locals. Overfishing followed, creating nutritional imbalances and pushing the lake’s ecosystem closer to collapse.
Pollution is now a more visible and urgent threat. A regional survey in 2025 – the first of its kind in over two decades – revealed serious contamination across 44 sites. Nutrient overload, heavy metals and plastic debris are choking the lake. Scientific analyses have placed Lake Victoria among the top ten most polluted lakes globally, citing high concentrations of microplastics in its waters, sediments and fish.
In Mwanza, environmental officers confirm that the lake has become a dumping ground for solid and liquid waste. At Mwanza North Port, vessels plying to Nansio Port on Ukerewe Island, stir up foul-smelling, slimy water. The Mirongo River, one of the lake’s main inlets, carries untreated sewage, industrial runoff and plastic waste straight into the lake. Water samples have tested positive for harmful bacteria and faecal contamination.
Pollution also comes from mining and agriculture. Fertilisers, pesticides and chemicals such as mercury, lead and even banned substances like DDT enter the lake from runoff. These pollutants pose a serious threat not only to aquatic life, but also to the health of lakeside communities who depend on the water for drinking and cooking.
As these pressures mount, aquatic weeds have spread unchecked. Water hyacinth has formed thick mats that block sunlight, suffocate fish and disrupt transportation. A newly discovered invasive plant species is also spreading rapidly and is yet to be controlled. It is particularly evident at Mwanza’s Capri Point beaches.
A former maritime safety officer at the Lake Victoria Basin Commission (LVBC), Dr Gerson Fumbuka, stressed the urgency of joint regional action. “The priority now is to accelerate implementation, strengthen coordination mechanisms and foster genuine ownership by all stakeholders to halt and reverse the degradation of Lake Victoria,” he told The Arusha News.
He further warned: “The lake’s ecosystem is in crisis. Overfishing, pollution and invasive species have severely depleted fish stocks and disrupted ecological balance – some areas are now effectively dead zones. Combined with the impacts of climate change, that threatens the survival of millions who depend on the lake for food, income and drinking water.”
In fact, some observers warn that even the currently highly promoted cage fishing has also not been properly studied for long term environmental and ecological impact.
Currently, the much promoted “cage fishing” has literally turned game fish into some kind of “broiler chicken,” artificially fed rather than letting the fish forage naturally. The long-term industrial feeds could one day prove disastrous, observers warn, not very dissimilar to the way the introduction of the Nile Perch has by and large, become a disastrous exercise.
Lake Victoria remains the heart of East Africa and even the Southern Africa Development Community (SADC). Fish from Mwanza often find their way to Zambia, DR Congo and even Mozambique. The lake’s slow decline is not inevitable. Reversing the damage will require urgent, coordinated and cross-border commitment – without which, livelihoods for millions will be lost and a generational legacy broken, threatening not only East Africa but including countries like Egypt and Sudan to the north as the lake is the source of the Nile River.
The lake’s decline has far-reaching consequences. A recent World Bank analysis warns that over 47 million people across the basin are at risk. The report calls for a $1.9 billion regional sanitation investment under the Lakewide Inclusive Sanitation (LWIS) Strategy. Without swift and coordinated intervention, the economic and health costs will continue to grow.
During the opening of the Kigongo–Busisi Bridge on June 19, 2025, President Samia Suluhu Hassan issued a direct warning: “We must act now to save Lake Victoria from proliferation of water hyacinth.”
Despite the grim outlook, there are signs of hope. Youth groups and local organisations in places like Mwanza, Bukoba and Kisumu have initiated lake clean-up drives and tree planting campaigns. Environmentalists continue to call for tighter pollution control, proper waste management and the revival of fish restocking programmes.
“We used to catch enough to feed our families and sell at the market,” says a fisherman from Sengerema who requested anonymity. “Now we go out all night and come back with barely anything.”
