Abstract: Seasonal variation in water quality during dredging process in typical brackish water from the Bonny River (Rumuolumeni axis) located around Eagle Island was analysed. This was done in different seasons using January/November as dry season and July/September as wet season. The following physico-chemical parameters were studied; temperature, pH, conductivity, Total Dissolved Solids (TDS), sulphate, phosphate, nitrate, alkalinity, chloride, Dissolved Oxygen (DO), Biochemical Oxygen Demand (BOD), fecal coliform count, Total hardness, Ammonia, Iron II and Turbidity. Standard methods of measurement and analysis were employed. Some graphical techniques and tabulations were also used to explain variations. The brackish water had significant temporal variations (monthly) recorded for sulphate, Total Hardness, Iron II, phosphate, nitrate and chloride, but spatial variation (up/down stream flow) affected fecal coliform count, sulphate, BODs, Total Hardness, Chloride, alkalinity and turbidity concentrations. Temporal and spatial seasonal variation during dredging affects some physico-chemical parameters.