The Sebou river watershed covers a surface of about 40 000 km2. Its water resources are estimated at 5600 billions of m3 representing almost 27% of the whole country superficial waters. However, by an important anthropological influence, this water is exposed to several agricultural, industrial and urban constraints. Thus, it is necessary to monitor water quality of this watershed. So; the present work gives a physicochemical typology of waters of this watershed by using the physicochemical evaluation of fifteen environmental parameters. For this purpose, sixteen stations were chosen in order to be representative as much as possible of the various sectors that constitute the prospected zone. The results have shown four groups of samples differing by the concentrations in magnesium, sulphates, carbonates, chlorides, sodium, potassium, nitrates and nitrites, and by the values of the conductivity and temperature. The value of the chemical oxygen demand and the concentrations in ammonium and in Calcium allows discriminating two categories of samples. Also, several zones of the studied environment were polluted, and the origin of this pollution was multiple: agricultural, industrial and urban.Also, certain physicochemical variations were linked to the ÂseasonÂ factor and to the anthropological activities connected to this change.