The rivers in Panama are the main sources of water for human consumption and their quality has been compromised. Between 2014 and 2015 samplings were made in the lower middle basin of the Santa María River, Veraguas; in the vicinity of the water reservoir of the water treatment plant. Four places were selected in the sector, where water samples were taken. The samples were analyzed by physicochemical and bacteriological variables. The data of the sites were compared during both, dry and rainy seasons. In the dry season, no significant differences were found between the sites for OD, conductivity, temperature and SST; the pH showed slight differences; and the counts of total coliforms and fecal coliforms were the same in all sampling sites. During the rainy season the physicochemical data (OD, conductivity, temperature, pH and SST) were similar in all sampling locations. All the variables were kept within the norms established by COPANIT. When comparing the dry and rainy seasons, no differences were observed between the two seasons of the year with respect to the physicochemical data; the comparison of Oxygen, conductivity, temperature, pH and SST values did not show significant differences (p> 0.05). No significant variations were found (p> 0.05) between the dry and rainy seasons for the values of total coliforms and fecal coliforms.