Assessment of the Water Quality Index of Otamiri and Oramiriukwa Rivers

Problem statement: The impact of anthropogenic activities on Otamiri and Oramiriukwa Rivers as a result of the increasing rate of urbanization in Owerri, Nigeria is of a great concern due to the fact that water from these rivers is the source of water distributed for public use. These rivers are of particular importance in the study of surface water pollution because effluents from industries, municipal waste, agricultural and urban run-off are discharged into it thereby deteriorating the quality. Approach: This study used the application of Water Quality Index (WQI) in evaluating the quality of Otamiri and Oramiriukwa Rivers for public usage. This was done by subjecting the 180 samples collected to comprehensive physicochemical and bacteriological analysis using APHA standard methods of analysis. Results: The overall WQI for the samples was 174.49. The high concentration of conductivity, color, total solids, turbidity, total coliform, iron, manganese, COD, BOD and nitrate were responsible for the high value of WQI which may be attributed to the anthropogenic interference along the river bank. The results of the analysis when compared with the Nigerian Standard for Drinking Water Quality (NSDWQ) permissible limit showed that the rivers were polluted and that the water is not safe for domestic use and would need treatment. Conclusion: The use of WQI in elucidating surface water quality evaluation and management has been demonstrated by this study. WQI is also valuable tool in categorizing the pollution sources of surface waters.