The surface water resources in the region of Bonoua are subject to strong anthropogenic pressures created by the development and expansion of agricultural activities and also by the agro-industrial and domestic activities. This impacts the available quantities of these resources that fluctuate throughout the year. Similarly, their quality is thereby also changed. Regarding the quality of these resources how can occur at a given time of year? This concern led in this study to assess the overall quality of surface waters of Bonoua region during the rainy season. It is based on the exploitation of data from a water sampling campaign conducted in July 2014. The data were processed with the Evaluation System of Quality of Waters, referred to as "SEQ-Eau" for determining the overall water quality. The (ACPN) has also been applied to the data for the identification of phenomena causing water pollution. The results show that in general the surface waters in the region are Bonoua of "average quality" to 92.86% and "poor" at 7.14%. The responsible alteration of this deterioration in the quality of surface water is the "acidification" parameter, which contributes to 64%. Alterations "temperature" and "organic and oxidizable materials" expressed as COD and BOD 5 incidentally involved in this deterioration in the respective proportions of 14 % and 22 %. The phenomena causing water pollution is anthropogenic. They are mainly from discharges of domestic and industrial waste water and the use of chemical fertilizers in the plantations. This evaluation of the quality of surface water in the region of Bonoua is a first draft that should be complemented by other studies covering aspects such as pesticides and microbiology for better management.