The demographic growth of the city of Abidjan is accompanied by an intensification of industrial and agricultural activities that are not correlated with the installation of efficient and adequate sanitation structures. Thus, most domestic, industrial and agricultural wastewater is discharged into the Ebrié Lagoon without any prior treatment. The objective of this study is to characterise the physico-chemical and bacteriological parameters of the waters of the lagoon bay in the commune of Yopougon. The framework of the methodology used to achieve this combines bibliographic research, laboratory analyses and semi-directive interviews. At the end of this methodology, the results showed a seasonal variability of the physico-chemical characteristics and the hydro-climate which condition the level of pollution of the waters of the lagoon bay of Yopougon. The values of salinity, pH, Nitrates, Nitrites and suspended solids remain within the limit authorised by the World Health Organisation for surface waters. On the other hand, the conductivity, phosphate, ammonium and dissolved oxygen levels are outside the standards set by the World Health Organisation. As for the bacteriological parameters, the strong presence of Total Coliforms, Clostridiums and Faecal Streptococci, indicate a strong bacterial contamination of faecal origin of the waters of this bay whose degree of pollution increases after the periods of rainy season..