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Where two rivers meet: battling pollution in the Athi River

The photograph captures a poignant moment where two rivers meet, each with its own tale to tell. The Tsavo River, fed by clean waters from Mt Kilimanjaro and Mzima Springs, encounters the Athi River, which, after its journey through Kenya’s largest city, bears the burden of severe pollution.

The vivid green algal bloom floating on the river’s surface serves as a strong sign of eutrophication, driven by elevated nitrogen and phosphorus levels, likely the result of human sewage discharge. Eutrophication can wreak havoc on river ecosystems, causing widespread death to aquatic life and vegetation. This article will explore the factors driving the severe pollution of this significant river, examine its environmental repercussions, and explore potential remedies for this pressing issue.

Athi River: A lifeline for Kenya

Stretching across 390 kilometres, the Athi River is Kenya’s second-largest river. It originates in the highlands, traverses the Athi Plains, merges with the Nairobi River, and gives birth to the renowned Fourteen Falls. Continuing its course south-eastward, it meets the Tsavo River. As it journeys through Tsavo National Park, it becomes known as the Galana-Sabaki River, ultimately flowing eastward to enter into the Indian Ocean, just 10 kilometres north of Malindi.

The Athi River’s vast catchment area covers 58,639 square kilometres, representing 10.2% of Kenya’s total land area. This region is home to 9.79 million people, constituting 25.4% of the country’s total population. The river’s significance extends beyond supporting wildlife, including crocodiles and hippopotamuses in Tsavo National Park, as it also plays a vital role in sustaining a substantial portion of Kenya’s populace.

The pollution problem

As the Athi River winds its way through Nairobi’s densely urbanized and heavily industrialized zones, it contends with severe contamination from multiple sources. Land use in these areas include urban, residential, industrial, transportation, agriculture, and livestock keeping, all contributing to the river’s pollution. The Athi River faces increasing clogging, laden with uncollected waste, human sewage, industrial discharges, agrochemicals, and petrochemicals.

Environmentalists and policymakers have raised alarms about the river’s soaring pollution levels. Among its sediment, high concentrations of heavy metals like Cadmium and Nickel have been detected, signalling significant agricultural runoff and petroleum spillage, likely originating from garages in the urban centres. Exposure to high concentrations of heavy metals can lead to severe organ damage and, in extreme cases, even fatalities.

Failing Fourteen Falls

Visitors to the once-pristine picnic destination of the famous Fourteen Falls now witness banks littered with plastic waste, dwindling wildlife, unsettling chemical foam accumulation, and a sparse presence of fishermen lamenting the vanishing fish population.

Researchers have further unveiled the Athi River’s transformation into a breeding ground for microbiological diseases. Water quality has plunged significantly below both national and WHO standards for drinking and agricultural use. This poses grave health risks for the millions relying on the river for their water needs. In one downstream village, a staggering 55.5% of the residents have linked their illnesses to river contact, with the most common ailments being typhoid and diarrhoea.

Marine impact

Where the Athi River meets the ocean, it carries nutrients and sediments vital for ecologically and economically significant habitats and species. However, excessive sediment input from unsustainable land use practices along the riverbanks has led to high turbidity in the ocean waters, reducing light penetration. This phenomenon damages mangroves and corals and disrupts the ecology, adversely affecting the livelihoods of local fishermen.

Implications for Tsavo’s wildlife

While there is compelling evidence to suggest that the Athi River’s pollution is adversely affecting populations along its banks, little research has been conducted on the impacts on Tsavo National Park’s wildlife. Bottom-feeding species like catfish have been reported to accumulate toxins from polluted riverbeds. If these fish are consumed by predators, toxins accumulate further up the food chain, a process known as bio-accumulation. Many species, including herons, fish eagles, kingfishers, and crocodiles, feed on these fish from the Tsavo River, raising concerns about the toxins’ impact from Nairobi’s industrial activities.

Seeking solutions

Recognizing a problem is the first step toward resolution. Several organizations have stepped up to address the extensive pollution threatening one of Kenya’s most vital rivers. Organisations such as Chemolex Company Ltd and Smart Villages Research Group have initiated the deployment of plastic capture devices along the Athi River and its tributaries, effectively recycling plastic waste into valuable products, including paving blocks. Kenya’s ban on single-use plastic bags in 2017 has also played a significant role in reducing plastic pollution, a common menace in Kenya’s rivers and waterways.

Providing clean water

At Tsavo Trust, we are acutely aware of the challenges that the local community faces in obtaining clean water, especially during the dry season. To address this critical issue, we’ve collaborated with Kamungi Conservancy, and together, we’ve made significant strides in ensuring a reliable water supply.

Tsavo Trust has successfully drilled three boreholes, one in Shirango and two in Kamungi. These boreholes provide a lifeline for the villagers, offering a dependable source of clean water. With access to these water supplies, local residents are no longer forced to rely on the Athi River during the dry season, substantially reducing their risk of contracting dangerous waterborne diseases like cholera and typhoid.

Plant power

Additionally, there’s mounting evidence supporting the effectiveness of riparian vegetation in intercepting and reducing pollutants in rivers. This natural vegetation along watercourse banks can reduce levels of total nitrogen (TN), total phosphorus (TP), and other pollutants through physical, chemical, and biological processes. The vegetation would help stop eutrophication and reduce the growth of thick green algae on the river’s surface. Riparian vegetation also provides habitats for macroinvertebrates, fish, and bird species.

Supporting and protecting vegetation growth, by demarcating riparian buffer zones and installing floating gardens could be effective in reducing the amount of pollution in the water and sediments. Protecting this resource for animals and humans alike.

Stop it at the source

To ensure the Athi River’s protection as a water source, it’s crucial to tackle pollution at its origin. This means enforcing strict regulations to prevent untreated chemical and industrial waste from entering the river. It also involves upgrading sewage infrastructure to prevent human waste from reaching water bodies, advocating for on-site treatment in industrial settings, and maintaining proper plastic waste management, even at disposal sites. Additionally, managing the use of fertilizers in agricultural areas is necessary to minimize excessive runoff into water bodies.

A striking image of the slimy green Athi River entering Tsavo National Park carrying a heavy burden of pollution reveals the far-reaching impact of urban and industrial actions upstream. With an ever growing population and rapid urbanisation, it’s essential to take collective responsibility, action, and dedication to solve this problem. It’s not just the defence of a river; it’s the preservation of life, for the aquatic creatures, for the environment, and for the millions that depend on it. By uniting organizations, communities, and enforcing source-level rules, we can help the Athi River recover and return to its cleaner state.

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