The study was carried out in the Timari river micro-basin belonging to the Río Negro district of the Satipo province, with the objective of evaluating the influence of the vulnerability to contamination of surface water resources in the Timari-Río Negro river micro-basin. The results in the physical aspect were: area 1061.16 ha with length of channel 7.36 km and 44 tributaries, slope of the channel 12%, mean elevation of 1176.47 meters above sea level; the biophysical aspect presents: temperature from 19.87°C to 24.16°C, precipitation from 1693 mm to 2063 mm, evapotranspiration from 1083.31 mm to 1519.81 mm and slopes ranging from flat to steep. The population in the socioeconomic aspect presents 40% illiteracy and 60% some degree of education, productive activities are based 83% on agriculture and 17% trade, monoculture predominates with 60% and diversified crops at 40%. The flow rate was 0.248 m3 /s; while the raw surface water quality index presents 81.28 characterized as good quality and ends with 41.87 as poor quality.