Variación espacial de la contaminación por coliformes fecales en el Río Portoviejo, Provincia de Manabí

This study evaluates the microbiological and physicochemical quality of the Portoviejo River, located in the Manabí province (Ecuador), through the analysis of fecal coliforms and parameters such as pH, temperature, electrical conductivity, total dissolved solids (TDS), and salinity. For this purpose, eight sampling stations were established along the main river course, from its source to its mouth, covering the cantons of Santa Ana, Portoviejo, Rocafuerte, and Sucre. A total of 48 water samples were collected in June 2023, and analyses were conducted both in situ and in the laboratory, following the Ecuadorian Technical Standard INEN 2176:2013 and Method 1060 of the Standard Methods for the Examination of Water and Wastewater. The results showed fecal coliform concentrations ranging from 1,600 to 160,000 MPN/100 mL, with station averages exceeding the maximum permissible limits established by Ecuadorian regulations for recreational and agricultural uses. The most contaminated station was located in the El Comercio neighborhood (Portoviejo), with 137,333.33 ± 39,259.82 MPN/100 mL. Statistical analysis revealed significant differences between stations (ANOVA, p < 0.05), and Spearman’s correlation showed a positive relationship between fecal coliform concentration and population size. Conductivity, salinity, and TDS values also reached levels that indicate restrictions for agricultural use in some sections. Higher contamination was identified in densely populated urban areas, and an action plan was proposed with strategies by canton to mitigate the observed impacts. Finally, a proposal was presented to reduce microbiological pollution.