NAIROBI, Kenya — The Kenya Wildlife Service (KWS) has launched investigations into a suspected chemical spill that is believed to be flowing into the Nairobi National Park ecosystem, raising urgent environmental and public health concerns in the capital.
In a statement issued on Thursday, KWS said its officers detected what appeared to be contaminated discharge originating from the Mlolongo–Athi Dam drainage system.
Preliminary assessments indicate that the polluted water is entering the park through the upper Mlolongo drainage corridor, a key feeder system into the park’s wetland ecosystem.
Officials described the water as unusually discoloured, with white, foamy effervescence, an indicator they say is consistent with possible chemical contamination.
Early observations suggest the discharge may be linked to industrial activity in the surrounding Mlolongo and Athi River industrial zones, though authorities have stressed that the exact source has not yet been confirmed.
“The flow exhibits characteristics consistent with chemical pollution and requires urgent verification through laboratory analysis,” officials noted in their preliminary assessment.
The contaminated water system feeds into the Mbagathi and Athi Rivers, both of which are critical to the Nairobi National Park ecosystem and downstream communities.
Environmental experts warn that any sustained chemical discharge into the system could threaten aquatic life, disrupt the park’s biodiversity, and affect water users downstream, including farmers and pastoralist communities relying on the Athi River basin.
The Athi River system is also a major water source for irrigation schemes and livestock along its lower catchment, increasing concerns about wider exposure.
KWS has activated a joint response involving the National Environment Management Authority (NEMA) and the Water Resources Authority (WRA) to trace the origin of the contamination.
Teams are currently conducting water sampling, laboratory testing, and upstream surveillance to identify possible discharge points and responsible facilities.
Authorities have also begun mapping industrial installations within the catchment area as part of the investigation.
KWS has urged residents and park users to avoid contact with the affected water systems while investigations continue.
The agency warned against fishing, watering livestock, or using water drawn from the suspected contaminated sections.
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Officials also called on members of the public to report any unusual wildlife behaviour or distress observed within the park and surrounding areas.
KWS reiterated that the discharge of untreated or hazardous waste into protected ecosystems is a serious offence under Kenyan environmental law.
The agency warned that any individuals or companies found responsible will face prosecution, heavy fines, possible closure of operations, and mandatory environmental restoration costs.
“KWS will pursue decisive legal action once investigations identify the source of the contamination,” the agency said.
The investigation comes amid growing concern over industrial pollution in rapidly expanding peri-urban zones around Nairobi, where enforcement challenges have previously been flagged by environmental regulators.
