Water pollution in Bali due to human waste and agricultural runoff is a serious concern. Social and cultural influences such as rigid social structures, tourism, and weak infrastructure contribute to water pollution on the island. In an attempt to quantify the extent of the pollution, nutrient concentrations and other relevant variables were measured at seven points along the Yeh Ho River seven times in June, 2013. Interviews were also conducted to provide social and cultural context. The results of the study indicate that nutrient concentrations increase significantly as the water travels downstream from 15 (± 1.9) to 40 (± 3.2) ppm nitrate-NO3 and from 0.16 (± 0.06) to 0.61 (± 0.06) ppm phosphorous-PO4. In addition, nutrient concentrations on June 18th were higher across all sampling sites than the measurements on other days by 9.0 (± 2.4) ppm nitrate-NO3 and by 0.53 (± 0.06) ppm phosphorous-PO4. Generally, the levels of N and P in the Yeh Ho River are significantly higher than the expected natural background levels of nutrients in rivers. These trends are likely attributable to significant, uncontrolled, anthropogenic inputs into the Yeh Ho River. The qualitative data corroborates this interpretation. Other explanations for this nutrient increase include changing uptake rate due to geomorphological changes of the river, or systemic error introduced by sampling downstream sites later. However, these factors are likely negligible relative to anthropogenic inputs.