The evaluation of water quality in urban rivers is a very important activity worldwide. In Ecuador, there is little research carried out to date, which generates the problem that state, provincial and municipal entities do not have updated values of water quality in rivers in urban areas. This is the case of the city of Chone, in the province of Manabí. Based on this problem, the objective of objective of the present investigation was to carry out a physical, chemical and biological diagnosis of the water quality in the sub-basin of the Chone river. Water quality was evaluated at 4 sampling points during the dry season (December) and the rainy season (March), using the Water Quality Index (WQI), with its modification of 9 parameters (fecal coliforms, pH, biochemical oxygen demand, nitrates, phosphates, temperature, turbidity, total dissolved solids and dissolved oxygen) proposed by the National Sanitation Foundation (NSF).