Trends in Water quality Deterioration in the Rift Valley: The case of Lake Nakuru, Kenya

Abstract

Lake Nakuru is a shallow hyper-eutrophic, alkaline and saline endorheic lake located in Rift Valley’s eastern arm. Despite its great importance, Lake Nakuru has undergone profound changes due to anthropogenic activities, mostly due to the amplification of industrial and agriculture activities, urban sprawl and rapid population growth in the last few decades. This paper examines the threats facing the lake in terms of water pollution and quality deterioration trends and its impacts on the Lake wetland.  The paper looks at the seasonal variations in the physio-chemical parameters of the surface water and to assess levels of Dissolved Oxygen (DO), Alkalinity and Total Dissolved Solids (TDS) and Suspended Sediment (TSS) in the surface water and sediments in the lake. A total of 20 samples were collected in the wet and dry season to measure pH, DO, alkalinity, TDS, TSS of the surface water and the lake water. The data were processed to descriptive statistics using SPSS and Excel in order to measure distribution trends, dispersions, disparities and associations and inferential statistics, specifically a two tailed t-test was used to assess the significant difference in the lake water parameters in the dry and wet season. Sewage and industrial pollution were amongst the top contributors of water pollution. Physio-chemical properties of the surface water varied in the dry and wet season. Measured pH, DO, TDS and TSS values were above the permissible limits for aquatic ecosystems. Total Dissolved Solids (TDS) were found to be higher in the dry season while alkalinity, DO and TSS concentrations were greater in the wet season. From the findings, the highest level of pollution was in the storm drain, Lake Center, mouth of River Nderit and Lamdiac. Seasonal variations showed there was a significant difference (p < 0.05) in DO, TSS levels between both the seasons. The study concludes that the main issues threatening Lake Nakuru are the disruptions to its water quality arising from human activities in the catchment area. Strict implementation of policies related to the protection of Lake Nakuru is required. Legal action should therefore be taken in respect of all of those sectors that discharge toxic chemicals into the feeding rivers and the lake. Public awareness of pollution issues and their implications in the lake is necessary. This can be done through environmental education, as it is critical to enhance, spread knowledge and enable communities to protect the integrity and complexity of nature and ensure that the use of valuable resources is fair and environmentally sustainable.

Key words: Water quality, Wetlands, anthropogenic impacts, sustainability

DOI: 10.7176/JEES/16-2-04

Publication date: September 28^th 2026