Water Quality Index: Important Instrument for Environmental Monitoring of Anambra State Central Senatorial Zone Water Resources

Abstract

Physicochemical parameters are fundamental indicators for assessing the quality and suitability of water for human consumption and ecological sustainability. This study evaluated selected physicochemical indices to determine the overall status and potability of surface water sources within the study area using water quality index (WQI). The key parameters examined included pH, temperature, total dissolved solids, dissolved oxygen, biochemical oxygen demand, chemical oxygen demand, ammoniacal nitrogen and phosphate to determine their influence on water quality and microbial proliferation. The results were compared with established permissible limits recommended by the World Health Organization (WHO) and other regulatory bodies to ascertain compliance and potential health implications. The cumulative findings demonstrated noticeable Oraukwu recorded the highest mean temperature (29.50 ± 0.01 °C), whereas Alor showed the lowest value (28.80 ± 0.05 °C). The highest pH was observed in Oba (6.61 ± 0.00), while Idemili North had the lowest pH (5.51 ± 0.02). Total suspended solids were greatest in Nri (9.50 ± 0.02 mg/L) and least in Dunukofia (0.72 ± 0.01 mg/L). Dissolved oxygen peaked in Umudioka (44.50 ± 0.30 mg/L) but was lowest in Awka South (36.50 ± 0.50 mg/L). Biochemical oxygen demand was highest in Nibo (44.80 mg/L). Chemical oxygen demand was highest in Njikoka and lowest in Awka South. Ammoniacal nitrogen was highest in Aniocha, while phosphate concentration was highest in Dunukofia. Statistical analysis revealed significant differences among the physicochemical parameters (p < 0.05). Furthermore, the twenty-one sampling sites showed WQI fall under category III (polluted category) and category II (slightly polluted category). The exceeding limits indicated contamination risks, while acceptable values reflected stability. Thus, physicochemical assessment using water quality index supports monitoring, risk evaluation, and sustainable freshwater protection integrity.