Assessment of Water Quality Index and Irrigation Indices in Ese Odo Area of Ondo State, Southwestern Nigerian

An assessment of the ground water quality was carried out in Ese Odo local government area of Ondo State, southwestern Nigeria. The study was aimed at examining the various samples of ground water and the quality of the ground water as it relates to drinking and irrigation purposes. Forty-Five ground water samples were taken from boreholes and open wells and analyzed for physical, chemical and biological properties. The results were compared with World Health Organization standards. The usefulness of these parameters in predicting ground water quality characteristics were studied and water quality index was determined from these parameters. In assessing the water for irrigation uses, indices such as percent (%Na), sodium adsorption ratio (SAR), residual sodium carbonate (RSC), permeability index (PI), Kelly’s ratio (KR), magnesium ratio (MR), equivalent salinity concentration (ESC) and Wilcox plot were used. The result obtained shows that the water studied has a mean value of 2.8 NTU for turbidity, 7.3 for pH, 294 μS/cm for electrical conductivity, 52mg/L for total dissolved solids, temperature 28.3°C, total hardness 41 mg/L, chloride 38.3 mg/L, calcium 15.8 mg/L, 5.64 mg/L for magnesium, nitrate 1.47mg/L, sulphate 51.7 mg/L, bicarbonate 15mg/L. Zinc, iron, manganese have mean values less than 1mg/L. The results indicated all the physicochemical parameters are within the recommended levels set by World Health Organization (WHO). Although traces of heavy metal and mineral oil contaminations are observed some of the samples. All the samples are plotted on the “Excellent irrigation class” of Wilcox plot with good/excellent irrigation indices. Consequently, the groundwater in the study area is good and suitable for drinking and irrigation purposes