Data and Code Repository for: Groundwater Quality and Trace-Metal Contamination Around a Dry Hydrocarbon Exploration Well in the Gongola Basin, Northeastern Nigeria: An Integrated Physicochemical, Spatial, and Multi-Index Assessment.

Inland hydrocarbon exploration frontiers such as the Gongola Basin of the Upper Benue Trough, Northeastern Nigeria, remain poorly characterised hydrogeochemically despite decades of exploration activity. This study presents a fully transparent, independently recomputed assessment of shallow groundwater quality around the Kuzari-1 exploratory well (Gombe State), drilled in 1999 to 1,666 m and classified as a dry hole. Twenty groundwater samples (one within a 4 km Impact Zone, nineteen within a 4–8 km Control Zone) were analysed in situ and by ion chromatography/spectrophotometry and ICP-MS for twelve physicochemical parameters and seven major ions/trace metals, benchmarked against World Health Organization (WHO, 2026) and Nigerian Standard for Drinking Water Quality (NSDWQ, 2022) guideline values. A Weighted Arithmetic Water Quality Index (WQI; ΣWi = 42) and the Mohan et al. (1996) Heavy Metal Pollution Index (HPI; Cd + Fe + Cu) were computed using exact-fraction arithmetic, and Inverse Distance Weighted (IDW, power = 2) interpolation was used to map nine parameters relative to the true wellhead coordinates (10.57536111° N, 11.06658333° E). Turbidity (90%), nitrite (65%), and iron (65%) exceeded regulatory limits basin-wide, while cadmium exceeded the 0.003 mg/L WHO standard at only three of twenty stations (S1, S15, S19), reaching 16.3 times the guideline value at station S15. Spatial and correlation analyses indicate that acidity (pH as low as 4.80) and cadmium are statistically concentrated near the wellhead (distance–cadmium r = -0.62), consistent with pyrite-oxidation-driven metal mobilisation in the Cenomanian–Turonian Yolde Formation, whereas nitrite and iron display diffuse, basin-wide distributions more consistent with agricultural and geogenic origins, respectively. The uncapped WQI classified 40% of stations as "Unsuitable" and 30% as "Poor", while the HPI flagged 15% of stations as "High Pollution", all three coinciding with cadmium-exceeding sites. These findings provide the first quantitative, spatially resolved baseline for groundwater quality in the vicinity of an inland Nigerian dry hole and support targeted remediation at the Zambe, Bura Babadala, and Banin Belle communities pending confirmatory hydrocarbon and barium analyses. This open-access repository contains the raw geochemical spreadsheets, field parameters, and live Python scripts used to process and model all data figures.