Water Quality Index as a Tool for the Assessment of the Health of Usuma Reservoir, in FCT Abuja Nigeria

Abstract

This paper assessed the water quality index (WQI) of Usuma reservoir. The samples were collected within an annual hydrological season covering both wet and dry seasons between June 2016 and May 2017. Twelve core water quality parameters which are critical and basic determinants of water conditions were analyzed in 72 water samples. The samples parameters includes: water temperature, pH, dissolved oxygen, electrical conductivity, total dissolved solids, biochemical oxygen demand, nitrate, phosphate, sulphate, total alkalinity content, total hardness and total iron. Pearson correlation coefficients were calculated to assess the extent of relationship between the electrical conductivity, water temperature, TDS and total iron indicating that as pH increases, these parameters decreased in value. ANOVA showed a significant difference (p<0.05) in electrical conductivity, pH, TDS, Total Iron, total alkalinity, total hardness and turbidity in the reservoir. Electrical conductivity (67.3 -150.2 mg/l), pH (6.73 – 8.5), sulphate (0.5 -14 mg/), total dissolved solids (37.75 – 115.5 mg/l), total alkalinity (20 58 mg/l, total hardness (22 80 mg/l) had their maximum values within the WHO range while Biochemical oxygen demand (0.5 – 4.82 mg/l), Dissolved Oxygen (3.89 -12.24 mg/l),Nitrate (0.1 8.35 mg/l), Phosphate (0.11 – 5.28 mg/l), total Iron (0.07- 3.28 mg/l), Turbidity (3.09-69NTU) were out of the WHO range. The WQI for Usuma reservoir was found to be 65.83. This confers the status of ‘average’ on it based on WQI category.