Utilising the National Sanitation Foundation Water Quality Index for Assessing the Water Quality Status of Eruvbi River in Benin City, Nigeria

Abstract

This study assessed the quality status of the Eruvbi River in Benin City, Nigeria using the National Sanitation Foundation Water Quality Index (NSFWQI). The physicochemical and microbiological parameters analysed were pH, temperature, turbidity, total dissolved solids (TDS), phosphate, nitrate, biochemical oxygen demand (BOD), dissolved oxygen (DO), and total coliforms. All parameters were analysed using standard methods. For each parameter, the temporal and spatial range were pH (5.3 - 6.2), temperature (22.0 - 28.0 ^oC), turbidity (5.0 – 128.0 NTU), TDS (20.0 – 128.0 mg/L), phosphate (0.1 – 1.0 mg/L), nitrate (0.2 - 0.8 mg/L), BOD (3.4 - 6.2 mg/L), DO (5.0 - 11.2 mg/L), while the mean for total coliform count ranged from (416.9 - 295120.5 CFU/100 mL). The results were compared against national and international standards with the temperature, TDS, and nitrate values within set limits, while the non-conforming parameters were majorly total coliform, phosphate, turbidity, and pH. The overall NSFWQI results indicated moderate water quality, with WQI values ranging from 54.04 to 61.95 at all sampling locations. The middle stream had the lowest NSFWQI value caused by effluent discharge from a carbonated drink industry. The moderate water quality means that additional treatment is required before the water can be considered safe for drinking and domestic purposes. The NSFWQI protocol makes it easier to explain the water quality to the general public and decision-makers, and it can be a valuable tool for water management.