Abstract
Context: Microbiological contamination of surface waters constitutes an environmental and health problem, especially in recreational uses involving direct contact. Objective: To evaluate the microbiological water contamination of the VRAEM River by determining thermotolerant coliforms at two points located downstream of the Pichari-Kimbiri bridge during four sampling periods in 2025. Methodology: A quantitative, observational, descriptive, and longitudinal study was conducted; eight environmental samples (January, April, August, and September) were analyzed using the Most Probable Number method. Results: Concentrations ranged from 1.9 × 10⁴ to 1.25 × 10⁵ MPN/100 mL; all exceeded the reference value of 200 MPN/100 mL, with exceedances ranging from 95 to 625 times. The downstream point showed increases from 26.1% to 50.6%; the highest concentrations occurred in September. Conclusions: The evaluated stretch presented persistent and high contamination; it is recommended to strengthen water surveillance and investigate its sources.