Meet Judith Koskey, Environmental Specialist and Mawazo Scholar

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Saving the Njoro River Watershed Ecosystem

By Judith Koskey

There is a pressing need to understand the consequences of human activities, such as land transformations, on watershed ecosystems. One of Kenya’s critical watersheds, the Njoro River, is important to the population of its catchment area as a source of water for domestic and industrial use. It is also of great economic value to Kenya through tourism and the conservation of its biodiversity. Moreover, Njoro River is the main feeder of Lake Nakuru, an important ecological site and habitat to Kenya’s famous flamingos. The river catchment area, however, has been steadily degrading over recent years.

Poor farming methods, overgrazing and deforestation are the most common cause of catchment degradation in Kenya.  In the case of the Njoro River, this begins from its source, the Mau forest, which is progressively being cleared to free up land for other purposes. In addition, increased agricultural activities in close proximity to the river have led to the contamination of the river with pesticides and fertilizers, extending far downstream to Lake Nakuru. Furthermore, pastoralists in the area keep large herds of cattle which overgraze on the catchment vegetation, leading to enhanced runoff, soil erosion and increased sedimentation in the river. Moreover, urban centres through which the Njoro River flows are rapidly expanding, creating increased pressure to the river’s already struggling ecosystem with general waste that is discharged with little to no treatment into the river.  A stark example of this ecosystem degradation is the impact on the flamingo population indigenous to Lake Nakuru, who are fleeing the lake in large numbers over recent years.

My research seeks to assess the potential effects of catchment disturbance on vegetation diversity, water quality and macroinvertebrate populations in the Njoro River. I will collect river water samples during the dry and wet seasons, and analyse them to determine the physicochemical parameters such as temperature, pH, salinity, dissolved oxygen concentration, and dissolved solids and nutrients (nitrate and phosphates). Second, I will study the macroinvertebrates in the water samples collected to determine their abundance and diversity by type. Macroinverterbrates have been used widely as indicators of pollution due to the varying levels of tolerance.  Finally, I will evaluate the efficacy of the efforts being made to conserve the Njoro River through The Njoro River Rehabilitation Project that has been active since 2012, to determine the extent to which these rehabilitation and conservation measures have been successful. My research findings will shed light on the impact of unsustainable land use practices on the river health and the socio-economic welfare of the residents in the Njoro River watershed area. They will also provide actionable recommendations for the way forward to improve management and conservation of the Njoro River watershed.


Judith Koskey is a PhD student at Egerton University’s Environmental Science department. Her research is on the assessment of catchment disturbance on vegetation diversity, water quality and macroinvertebrate abundance and diversity in Njoro and Kamweti rivers, Kenya. She was born and raised in the Njoro River watershed area in the Rift Valley, and continues to reside there alongside her family and friends. She is therefore passionate about using her research to help preserve this critical natural resource for the welfare of her community and for future generations.