MICROBIOLOGICAL AND PHYSICOCHEMICAL ASSESSMENT OF OSUN RIVER IN OSOGBO METROPOLIS

This study reviews the microbiological and physicochemical quality of Osun River in Osogbo metropolis. The river is environmentally and culturally important, including its association with the Osun-Osogbo Sacred Grove, a UNESCO World Heritage property through which the river meanders. Available evidence shows that the river has been used for domestic, recreational, and other purposes, but is vulnerable to contamination from urban, agricultural, and other human activities. Published work on Osun River and related Osogbo surface waters reports generally acceptable pH values in many locations but recurring concerns with turbidity, suspended solids, organic load, and microbial contamination. In one long-term Osun River study, average values included pH 7.6±0.5, electrical conductivity 216±380 µS/cm, total dissolved solids 111±200 mg/L, turbidity 34±43 FTU, dissolved oxygen 7.90±3.00 mg/L, biochemical oxygen demand 6.90±7.50 mg/L, and chemical oxygen demand 135±120 mg/L; the study noted that turbidity was outside most drinking-water guideline ranges. In a wider Osun State river survey that included the Osun-Osogbo station, the Osun site recorded pH 6.9±0.1, turbidity 9.46±0.3 NTU, and conductivity 300±4 µS/cm, while total coliform counts across sampled rivers ranged from 49 to 136 CFU/mL and exceeded safe-drinking microbiological limits. This paper adopts a qualitative documentary review method and concludes that Osun River in Osogbo metropolis shows signs of physicochemical impairment and microbiological contamination, making untreated use unsuitable for drinking and a potential public health concern.