Assessment of Groundwater Quality in Nasarawa West, Nigeria: Physicochemical Parameters, Seasonal Variation, and Water Quality Index Evaluation

Abstract

Groundwater quality in rural communities of Nasarawa West Senatorial District, Nigeria was assessed through physicochemical analysis and Water Quality Index (WQI) computation. Fifty water samples from boreholes and hand-dug wells across five Local Government Areas (LGAs) (Karu, Keffi, Kokona, Nasarawa, Toto) were collected in dry and wet seasons. Key parameters (pH, total dissolved solids, electrical conductivity, turbidity, dissolved oxygen, biochemical oxygen demand, nitrate, phosphate, sulfate, chloride, hardness) were measured and compared to World Health Organization (WHO) and Nigeria Standard (NSDWQ) guidelines. Results indicate slightly acidic to neutral pH (6.1–6.8) and moderate mineral content (TDS 149–426 mg/L in wet season boreholes) within permissible limits, but turbidity and nutrient levels varied widely by location and water source. Seasonal trends were evident: rainfall dilution improved some water quality parameters (e.g. nitrates and TDS in certain LGAs), whereas others experienced contamination spikes (e.g. Toto well turbidity). The computed WQI revealed all borehole sources as “Good” quality (WQI < 50) year-round except Toto’s boreholes, which were marginally poorer (WQI ~58 68). In contrast, shallow hand-dug wells often showed oor to unsuitable quality (WQI > 100), especially during the dry season in Nasarawa (WQI 461) and the wet season in Toto (WQI 887). Spatially, water quality challenges were most severe in Nasarawa and Toto LGAs, whereas Karu, Keffi, and Kokona fared better. The discussion interprets these findings in the context of sustainable development goal 6 (SDG-6) for safe water, highlighting how rural groundwater sources remain vulnerable to seasonal and anthropogenic influences. We recommend prioritizing borehole development, protecting wellheads from contamination, and regular monitoring to improve drinking water safety in the study area.