Assessment of baseline physico-chemical parameters and bathymetry mapping of Mahin Lake has been carried out for effective and sustainable utilization, management, conservation, and exploitation of its resources. pH, temperature, dissolved oxygen, electrical conductivity, resistivity, total dissolved solid (TDS), salinity, and surface pressure were determined in situ; while concentrations of calcium, magnesium, sodium, potassium, chloride, nitrate, and phosphate in water samples were determined in the laboratory. Bathymetry map revealed that the deepest portion of the lake is 4.3 m, while surface area and estimated volume of water were 1.82×106 m2 and 4.48×106 m3, respectively. The parameters measured shows considerable spatial variations. Mahin Lake is classified as a freshwater lake, indicating little interaction with the Atlantic Ocean; while its water is classified as ‘soft’ and weakly mineralized considering Ca2+ (0.46 to 1.69 mg/L), Mg2+ (0.55 to 1.83 mg/L), pH (5.05 to 5.5) and electrical conductivity (72.75 to 95.75 µS/cm). With these result, growth, biodiversity, and productivity of marine organisms within the lake are at risk. The low dissolved oxygen concentration (DO, 0.04 to 0.91 ppm) tends towards anoxia status and can possibly cause fauna depletion. Trace anthropogenic impact were identified on the western flank of the lake. The status of the lake provides a guide to further research in determination of its tectonic evolution. Sustainable environmental management system is required to prevent possible anthropogenic activities which can further reduce the quality of Mahin Lake and its associated ecosystem.
Key words: Mahin Lake, physico-chemical, bathymetry, anthropogenic, anoxia.