ASSESSMENT OF THE WATER QUALITY AND SEASONAL VARIATION USING PHYSICOCHEMICAL PARAMETERS FROM SELECTED DAMS AND WATER PANS IN WEST POKOT COUNTY, KENYA

Abstract

West Pokot County lies within the arid and semi-arid regions of Kenya, with the area experiencing erratic annual rainfall, high temperatures hence prone to high evaporation rates. Water resources in the area are not well developed, and as a result, the county faces frequent incidents of water scarcity and pollution. This study aimed to evaluate the potability of water by assessing temporal and spatial variation of physicochemical parameters in three dams (Siyoi Muruny, Nakuyen and Sook) and three water pans (Pampa, Kitalakapel and Limangole) from four sub-counties of West-Pokot county.  Samples of water were collected during wet and dry seasons of 2025; Apri and November respectfully and transported in ice boxes to the lab for analysis using standard AOAC procedures after in situ measurements had been taken using respective portable parameters. Water quality index (WQI) was calculated using the Weighted Arithmetic Index Method (AIM). The results were then analyzed descriptively and statistically by use of one-way ANOVA and t-test to find both temporal and spatial variabilities as well as significant differences (p≤0.05) and a comparison made with the set standards by World Health Organization (WHO). The pH (4.0-7.9) revealed seasonal variability with high acidity during the dry season at Nakuyen (4.0) and Pampa (5.0) indicating intense organic matter decomposition and reduced buffering. Water temperature were lower during the wet season (12.8 °C–31 °C) and specifically, Kitalakapel Pan (15.02 ± 2.33 °C) and highest at Pampa Pan (21.38 ± 1.83 °C). During the dry season, temperatures increased with Pampa Pan recording highest (29.02 ± 1.73 °C) probably due to increased solar radiation, reduced inflow, and higher evaporation rates which influences many physical, chemical, and biological processes in aquatic systems. The WHO does not set a strict universal temperature limit for natural surface waters used for domestic purposes. The WHO does not prescribe a strict health-based guideline value for Electrical Conductivity (EC) in drinking water but UN WWAP (2010) recommends a maximum of 1,000 µS/cm, all wet season values were within recommended limits and lower than dry season which recorded slightly above limit value at Pampa (1005±37.19). Dissolved Oxygen (DO) concentrations were higher during the wet season ranging from 8.50±0.82 to 9.89±0.90. Biochemical Oxygen Demand (BOD)’s recommended levels should be ˂5 mg/L, the values ranged from 6.30±0.58 to 7.92± 0.78 mg/L during the dry season. The WHO recommends that COD levels be ˂ 50 mg/L to maintain acceptable water quality and it ranged from. 53.96±9.12 to 62.08±5.57 during the dry season. Total Suspended Solids (TSS) was higher during the wet season with values ranging from 37.80±3.70 to 57.94±2.40. Water Quality Index (WQI) values classified all sources as very poor during wet season and unsuitable during the dry season after ranking WQI using 5-point Likert scale. Water pans recorded worse quality than dams (p < 0.05). This pollution suggests high anthropogenic influence and floods. It is therefore recommended that proper attention needs to be given to the dams and pans by appropriate authorities as well as continuous monitoring to prevent poor health implication on the households relying on this water for domestic use, livestock and irrigation.