APPLICATION OF WEIGHTED ARITHMETIC INDEX FOR THE ASSESSMENT OF BAKOLORI DAM WATER QUALITY FOR DRINKING

This study evaluated the drinking water quality of Bakolori Dam, Northwestern Nigeria, using the Weighted Arithmetic Water Quality Index (WQI) method over a three-month period (November 2021 to January 2022). Water samples were collected from four stations (S1–S4) using 750 ml plastic bottles and analyzed for key physicochemical parameters using standard procedures from APHA and the U.S. EPA. Results indicated elevated levels of turbidity (170–249 NTU), biochemical oxygen demand (20.8–23.1 mg/L), total suspended solids (16.7–26.7 mg/L), and iron (10.26–58.98 mg/L), all exceeding NSDWQ permissible limits. Other parameters such as pH (6.9–7.5), dissolved oxygen (7.8–9.2 mg/L), phosphate (0.133–0.146 mg/L), nitrate (2.9–3.4 mg/L), copper (0.30–0.50 mg /L), and zinc (0.28–1.19 mg/L) remained within acceptable limits. WQI scores for the four stations were: S1 – 1669.93, S2 – 1013.90, S3 – 2718.20, and S4 – 2575.00, classifying all as unsuitable for drinking. Similarly, monthly WQI values were: November – 440.40, December – 8262.29, and January – 3032.65, showing a significant decline in water quality over time. The high WQI values reflect cumulative impacts of agricultural runoff, erosion, and unmanaged human activities in the catchment area. The study underscores the urgent need for integrated watershed management, pollution control, and enhanced water treatment strategies to ensure safe water supply and protect public health.