A. O Talabi^1,, O. L. Afolagboye¹, M. N. Tijani², J. A. Aladejana², A. K. Ogundana³

Surface water is an important water resource for drinking and irrigation purposes in the central part of Ekiti-State. The water bodies are used with little attention to their quality status in addition to increased threat of anthropogenic contamination in view of rapid growth in population. The objectives of this study were to determine the physico-chemical characteristics of surface water, its hydrochemical controls and suitability for drinking and irrigation. Forty surface water samples were investigated. Field measurements of physical parameters were preceded by chemical analyses of the samples for major ions concentrations and bacteriological content. The surface water has pH ranging from 8.3 – 9.6 implying that the water was barely alkaline. Electrical conductivity [<205 µS/cm] and total dissolved solids [<154 mg/l] were low suggesting low-mineralised freshwater. The relative abundance of major ions [mg/L] was Na⁺>Ca²⁺>Mg²⁺>K⁺ for cations and Cl^- >SO₄^2-> HCO₃^->NO₃^- for anions. Major ion concentrations were low and within the WHO guidelines for drinking water indicating chemical suitability of surface water. The water samples tested positive to total bacterial count and E – coli with median values of 31.50 and 8.00 (cfu/100ml) respectively. Main water types and proportions were [70 %] mixed Ca²⁺-Mg²⁺-Cl^-, [20%] Na⁺-Cl^- and [10%] Ca²⁺-Cl^-. Predominant processes influencing water chemistry were incongruent dissolution/weathering of silicate minerals and cation-exchange of Na⁺ in rocks for Ca²⁺ in water. The low major ion concentrations indicated low water-rock interactions and short residence time. Irrigation quality indices [Sodium absorption ratio, salinity hazard, Kelly ratio and permeability index] revealed that the analysed water was suitable for irrigation.

freshwater, total bacterial count, E – coli, water chemistry cation-exchange