Physico-Chemical Status of Eleyele Reservoir, Ibadan, Nigeria

Eleyele reservoir is a vital resource for fishery, domestic water supply and flood control. Unfortunately, the reservoir is fast being degraded due to various anthropogenic activities around its catchments. Hence, this study evaluates spatio-temporal variations in the physico-chemical parameters of the reservoir. Eleyele reservoir was stratified into five zones (S1-S5) based on hydrological features and three sampling points were randomly selected per zone. Water samples were collected bi-monthly from each station for 24 months covering wet (May-November) and dry (December-April) seasons. Water parameters were analysed for alkalinity (mg/L), phosphate (mg/L), Dissolved Oxygen (DO, mg/L), Biological Oxygen Demand (BOD, mg/L), Chemical Oxygen Demand (BOD, mg/L) and temperature (°C) following standard procedures. Highest and least alkalinity (103.63 ± 14.87; 96.25 ± 11.41) and phosphate (2.00 ± 0.69; 1.94 ± 0.66) were recorded in S2 and S4, respectively. Temperature and DO ranged from 26.53 ± 2.20 (S5) to 26.86 ± 2.45 (S1) and 4.24 ± 0.84 (S2) to 5.39 ± 0.82 (S5), respectively. Alkalinity were 99.72 ± 12.41 and 100.91 ± 16.14, phosphate (1.71 ± 0.55; 2.10 ± 0.61), temperature (28.20 ± 2.34; 25.53 ± 1.74) and DO (4.48 ± 0.98; 4.85 ± 0.97) in dry and wet seasons, respectively. The mean values obtained for Biological Oxygen Demand (4.29 ± 2.23 mgl-1), temperature (26.64 ± 2.36), conductivity (0.270 ± 0.21 μScm-1), alkalinity (100.42 ± 14.69), hardness (69.18 ± 30.94 mgl-1) and ions were within desirable limits for aquatic life. Crucial steps should be taken to reduce agricultural activities and anthropogenic discharges into the Reservoir.