GROUNDWATER QUALITY ASSESSMENT USING WATER QUALITY INDEX IN SOME PARTS OF ODEDA, SOUTH-WESTERN NIGERIA

Groundwater quality samples were collected from boreholes and hand-dug wells located in some parts of the study area and were assessed for some physico-chemical parameters including pH, Electrical Conductivity, Total Dissolved Solids, total hardness, chloride, sulphate, nitrate, calcium hardness, magnesium hardness, potassium, iron and alkalinity. The results showed that most of the water quality parameters fell below the WHO maximum permissible limits with a few exceptions in about three locations. The quality indices were determined for each location and the values were found to be 20.86 – 57.40 indicating that about 75% of representative samples of the locations were good while about 15% was classified as poor. This can be attributed to high concentration of nitrates, EC, sulphates and total hardness in a few sample locations. The general low water quality index may have resulted from better sanitary conditions and improved living standards as well as the fact that the study was conducted at the peak of the rainy season. This type of assessment could be used as a powerful tool for making decisions and implementing water related policies as it documents water quality results that is easily understood by stake holders