Current World Environment

The water quality index (WQI) is important because it aids in understanding complex water quality data. Hence, WQI of Imiringi River was evaluated in order to classify quality grade of the water in unambiguous terms. Apart from seepages emanating from oil installations that are located further upstream of Oswan community, dumpsite leachates and agricultural run-offs are some of the likely nonpoint sources of pollution. Because the river ebbs away during the dry term, samples were collected in the rainy period of August 2019 at duplicate points across five field locations. Physical and chemical tests were carried out for ten (10) water samples following standard analytical protocols. Results obtained are: conductivity (32.7 ± 2.7 µs/cm), iron (2.57 ± 0.53 mg/L), dissolved solids (18.1 ± 1.4 mg/L), pH (5.2 ± 0.1), alkalinity (1.1 ± 0.1 mg/L), hardness (1.4 ± 0.2 mg/L), calcium (0.34 ± 0.03 mg/L), magnesium (2.08 ± 0.32 mg/L), dissolved oxygen (10.5 ± 0.7 mg/L), chloride (9.8 ± 0.7 mg/L), nitrate (0.12 ± 0.04 mg/L) and biochemical oxygen demand (0.36 ± 0.08 mg/L). Generally, iron and pH values fell short of regulatory standards while pH represented the most significantly varying parameter (p < 0.05) across all locations owing to human influences and dilution effects across the watercourse. Also, conductivity and dissolved solids depicted the strongest inter-parameter association. Overall, the downstream section of river revealed the poorest water quality condition while the entire river stretch was classified as being unsuitable for drinking even though it can support aquatic life.