Agrochemical inputs remain central to agricultural productivity in sub-Saharan Africa, yet their indiscriminate use continues to present a growing challenge to environmental and human health. This study examines the occurrence, spatial distribution, and socio-economic implications of agrochemical residues—particularly organochlorine pesticides (OCPs)—in selected areas of the Kogi River catchments of Kogi State, Nigeria. Using a mixed-method approach, the research integrates laboratory analyses, GIS-based spatial interpolation, and community-level surveys. A total of twenty water and twenty-five soil samples were collected during wet and dry seasons, analyzed for physicochemical parameters, mineral residues, and pesticide concentrations. Spatial mapping was undertaken using Inverse Distance Weighting (IDW) in ArcGIS 10.5 to illustrate pollutant distribution. Additionally, socio-economic surveys (n = 250 households) assessed agrochemical handling, application rates, disposal practices, and awareness of pesticide regulations.

Results reveal persistent contamination of soil and water resources, with concentrations of OCPs such as aldrin, endosulfan, dieldrin, and dichlorvos exceeding international thresholds in several locations. Fertilizer residues were also prominent, with nitrate and phosphate enrichment contributing to eutrophication in low-flow areas. Farmers reported pesticide application rates between 5–10 L per hectare, with over 40% applying ≥10 L, significantly above recommended limits. Improper disposal of containers was common, with 58% discarding them directly on farmland. Spatial GIS analysis demonstrated localized hotspots of contamination, strongly linked to farming intensity. The persistence of banned pesticides, coupled with poor awareness of safe practices, underscores weak regulatory enforcement and potential risks to both ecosystems and human livelihoods.