The State of the Bui Reservoir: Evaluation of Water Quality Using Physicochemical Parameters—A Decade After Impoundment

Abstract

Impounded dams can deteriorate water quality and affect its potability; yet, changes may also result from natural processes rather than solely from damming. A decade after the impoundment of the Bui Reservoir in Ghana, this study comprehensively assessed the water quality at seven sampling stations (October 2020-November 2021) by analyzing 26 physicochemical parameters. Profiles of pH, temperature, and dissolved oxygen were measured in situ using a YSI EXO II Sonde. Principal component analyses identified sulfates, total dissolved solids, alkalinity, total hardness, calcium hardness, magnesium hardness, and conductivity as key parameters influencing Bui Reservoir's water quality across pre-wet, post-wet, dry, and wet seasons. Most parameters were within WHO/EU/USEPA freshwater standards, except turbidity, color, and ammoniacal nitrogen. Spatial and temporal trends showed a general decrease in concentrations of many physicochemical parameters since impoundment. Compared with other major Ghanaian reservoirs, Bui recorded the lowest concentrations for most nutrients and ions, indicating improved water quality despite minor inputs from agricultural runoff and market-area waste. This study provides the first decade-scale, multiseasonal assessment of Bui Reservoir's water quality, combining extensive physicochemical data with multivariate analysis. It establishes a robust new baseline and offers actionable evidence for managing large tropical reservoirs under increasing land use and climate pressures.