A STUDY ON WATER QUALITY ASSESSMENT OF KIRI RESERVOIR, ADAMAWA STATE, NIGERIA

Abstract

This investigation constitutes the first rigorously designed, year-round, multi-site physicochemical characterization of Kiri Reservoir; a strategically vital yet scientifically neglected inland water body in Adamawa State, Nigeria. No comparable peer-reviewed baseline exists for this reservoir or any impoundment in the Gongola River system, rendering the present dataset an unprecedented scientific reference for regional aquatic science and fisheries governance. Unlike prior fragmentary reports, this study integrates temporal dynamics, spatial heterogeneity, inter-parameter correlation analysis, and international-standard compliance evaluation within a single unified analytical framework. Water samples were collected monthly from three geographically distributed sites over a complete 12-month hydrological cycle (January–December) and analyzed in accordance with standard methods (APHA, 1992). Two-way ANOVA with Tukey's post-hoc comparisons assessed seasonal and spatial effects; Pearson product-moment correlation analysis quantified inter-parameter relationships. Statistically significant seasonal variation was documented across all measured parameters. Dissolved oxygen (DO) declined to near-critical levels (minimum 4.2 mg/L) during the dry season, while ammonia nitrogen peaked at 0.42 mg/L approaching the accepted toxicity threshold of 0.5 mg/L NH₃-N. Biochemical oxygen demand (BOD) and nutrient concentrations were appreciably elevated during the rainy season, reflecting intensified agricultural runoff from the Gongola catchment. Spatial variation across the three sampling sites was statistically non-significant, confirming a well-homogenized system. Strong negative correlations between temperature and DO (r = −0.68) and between DO and ammonia (r = −0.71) exposed a mechanistically coherent cascade of compounding dry-season stressors with direct relevance to fish physiology. Overall water quality remained within acceptable limits for fish production throughout most of the annual cycle; however, the convergence of hypoxia and near-threshold ammonia during the dry season constitutes a recurring ecological bottleneck requiring targeted management. Mesotrophic phosphorus levels additionally signal a latent eutrophication risk under conditions of escalating agricultural pressure. The baseline established here is indispensable for evidence-based fisheries management and long-term environmental monitoring in Adamawa State.