How unchecked growth is killing Nairobi's natural lifelines

Nairobi Dam Suffocated by Hyacinth as Families Risk Life on the Edge”
Unchecked settlement and invasive.[ Peter Muiruri]

Nairobi’s surging population is tightening its grip on the city’s fragile natural lifelines, pushing forests and other natural buffers against floods and heat to the brink.

Lately, Karura and Ngong forests have seen some encroachment with some government agencies said to be complicit in the matter.

As estates rise and infrastructure shrinks, the forests, which are meant to regulate temperatures are being eroded through commercial developments signalling a looming crisis where the very resources meant to protect Nairobi collapse under the weight of its growth.

Even Nairobi National Park, the first one in Kenya and that acts as a flood plain in addition to wildlife conservation, continues to attract, albeit in a subdued manner, commercial interests.

In comments that attracted a public outcry, Central Organisation of Trade Unions Secretary General Francis Atwoli had in June 2025 called for the closure of park in order to accommodate the city’s burgeoning population.

The park was set up in December 1946 in order to conserve the wildlife that was roaming around the city.

Already, the park’s boundaries had to be adjusted during the construction of the Southern bypass in 2012. A section of the new Nairobi-Suswa standard gauge railway line traverses the park.

Apart from being hemmed in by highways, railways and estates, the industrial sprawl threatens its ecological balance through chemicals that seep into the fragile ecosystem.

Mairura Omwenga, an urban planner, says Nairobi has so far held on to these natural resources that moderate temperatures within the city thus making it an attractive place to live.

“The forests and the park within Nairobi act as the lungs of the city. Trees release oxygen and suck up carbon dioxide, making the city liveable. If the lungs collapse, we collapse too,” he says.

Omwenga says replacing the park and other green features with hard surface creates more runoff water and makes flooding worse.

“It used to rain in the 1960s and 70s but there was more green cover that absorbed much of the water. Now, even a small amount of rain in the city results in more runoff water that overwhelms the city’s drainage infrastructure,” he says.

Nairobi Dam, the 88-acre reservoir that was constructed in 1953 to control flooding, serve as a recreational facility including water sports and birding activities is now more of a sewer than a fun spot.

Sailing club

Early photos of Nairobi Dam show families enjoying boat rides and others fishing in the dam, activities that are impossible today. A signpost from the Langata side of the dam indicates that the dam once hosted a vibrant sailing club, a distant memory to many residents who have lived in this area for decades.

“We moved here in the late 1980s and the dam was a beautiful thing to just look at. Now it looks more of a shamba than a dam,” says Dan Maina who lives in the nearby Dam Estate.

In the late 1990s, the dam was choked by water hyacinth, a highly invasive plant that chokes water bodies and which is difficult to eradicate. Thereafter, silt and sewage began seeping into the dam, turning it, as Maina says, into a ‘farm’ where locals are propagating various crops such as arrow roots, sugarcane and vegetables, oblivious of the health impacts of those consuming them.

On a sunny Wednesday afternoon, Agnes Wangari sits outside her iron sheet home in Kambi Moto, an informal settlement on the edge of Nairobi Dam. She is cleaning some arrow roots which she hopes to boil for her children that evening.

Ever since she moved here over ten years ago, her and her family have been battling various respiratory ailments and looking around, it is not difficult to see why. One wall of her house almost touches the dam, now choked with sewage from the nearby informal settlements including Kibera.

Like hundreds of Nairobi residents who have built their homes on the edge of the dam, and some right in the middle, Wangari sees nothing wrong in consuming foodstuffs grown on the once-flourishing water body.