Assessment of water quality of Obueyinomo River, Ovia North East Local Government Area, Edo State, Southern Nigeria

Abstract

This study was carried out to assess the water quality of Obueyinomo River using water quality index. Ambient and water temperatures were determined in-situ while total dissolved solids (TDS), total suspended solids (TSS), total solids (TS), turbidity, pH, conductivity, hardness, alkalinity, dissolved Oxygen (DO), Biochemical Oxygen Demand (BOD), chloride, nitrate, phosphate, calcium and magnesium levels were analyzed in the laboratory using standard techniques. With the exception of DO, the other physicochemical parameters showed no significant difference (p>0.05) across the stations. Distribution patterns of physicochemical parameters in stations 1, 2 and 3 were analyzed using PCA. There was a strong association for stations 1, 2 and 3 which was also highly associated with nitrates. Hardness, magnesium calcium and phosphate formed a cluster showing the contributions of these ions to water hardness. Alkalinity, suspended solids and chloride formed a cluster suggesting that the suspended solids are largely composed of chlorides. Turbidity, pH, BOD and DO at all the stations exceeded the Federal Ministry of Environment standards for surface water. The water quality index (WQI) values at stations 1, 2 and 3 were 138.45, 122.70 and 170.01 respectively. The parameters responsible for the high values of WQI as indicated by the water quality rating include turbidity, pH, dissolved oxygen and biochemical oxygen demand. The high WQI values in all the stations studied which exceeded the benchmark of 100 showed that the water from this river is unfit for drinking purposes and should be treated before consumption by inhabitants of the area.

Keywords:  Physicochemical parameters, River, Water quality index, Contamination