Description of sampling points.

This study evaluated the impact of palm oil mill effluents (POME) on the water quality of the Agbogbo stream by analysing physicochemical parameters and calculating the Water Quality Index (WQI) across five sampling stations (A–E), including upstream, discharge, and downstream points, over a twenty-month period. Parameters such as temperature, pH, turbidity, total dissolved solids (TDS), total suspended solids (TSS), nitrate, sulphate, and conductivity were measured using standard methods. Results showed that the WQI values ranged from 60.1 to 65.5, with the lowest observed at the effluent discharge point, and an overall average WQI of 64.04, indicating poor water quality unsuitable for potable use. The consistent degradation in water quality across all sites highlights the adverse impact of untreated POME on aquatic ecosystems and community health. Practical implications include the urgent need for effective wastewater treatment prior to discharge, stricter enforcement of environmental regulations for palm oil mills, and continuous water quality monitoring. Future efforts should involve treating of the palm oil mill effluents before discharging it into the nearby waterbody, stakeholder engagement and sustainable practices in palm oil processing to safeguard water resources.