Water quality is crucial for the survival of living organisms and their environment. To monitor and minimize pollution, the Water Quality Index (WQI) is commonly used. This study utilized The WQI was used to evaluate the water quality of the Fervença River in Bragança, Portugal from January to June 2022. Water samples were collected monthly from five locations along the river. The WQI, which is based on physical, chemical, and biological parameters, provides a comprehensive numerical assessment ranging from 0 to 100. In general, points 1 to 4 exhibited a good WQI and showed similar results. However, at point 5, reduced WQI values were consistently observed in all sampling campaigns, indicating a likely connection with discharge from the nearby wastewater treatment plant. The winter season, which is typically characterized by higher rainfall in the region, experienced severe drought during the study period. Consequently, the influence of rainfall on the WQI parameters could not be evaluated as expected, particularly from January to March. Comparing the obtained results, it is evident that as the Fervença River flows through the city of Bragança, the water quality indices decrease in most campaigns, particularly after point 5. This finding highlights the negative influence of the city on the river water quality. This study highlights the importance of assessing the water quality. Points 1 to 4 demonstrated good water quality, whereas point 5 showed reduced quality linked to the wastewater treatment plant. Drought and city influence affected the river's water quality.