Surface waters in urban areas are subject to increasing anthropogenic pressures, driven primarily by poor waste management, domestic discharges, and agricultural activities. This study assesses the water quality of the Koh River and Beau Séjour Lake in Man (C？te d’Ivoire) to identify main pollution sources and evaluate environmental degradation using the Organic Pollution Index (OPI), Heavy Metal Pollution Index (HPI), and Water Quality Index (WQI). Nineteen sampling points were monitored, including fourteen on the Koh River and five across Beau Séjour Lake. Physico-chemical, chemical, and metallic parameters were determined through field measurements and laboratory analyses. Solid waste dumping was identified as the predominant pressure, occurring at 91.7% of the river stations and 80% of the lake stations. Market gardening and discharges from showers and septic tanks also represent significant pollution sources along the river. The results reveal pronounced organic pollution in the river, with critical degradation at stations S5, S8, and S10, while the lake exhibits severe localized degradation at stations S2 and S3. Although the risk of heavy metal contamination remains generally low, a critical threshold was breached at river station S1 (HPI = 154.9). The WQI confirms severe water quality deterioration: thirteen of the fourteen river stations and two lake stations are classified as unsuitable for use. Overall, these findings demonstrate that organic pollution, driven by diverse and intensive anthropogenic pressures, is the primary factor degrading these urban water bodies.
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