River water quality in the Pahang River and its adjacent tributaries is facing degradation due to increasing anthropogenic activities along the river bank. This study was initiated with the aim of investigating the effects of human activities and its impacts on water quality and water quantity. The spatial and temporal changes, as well as the human activities along this river are determined by analysing and calculating the water quality Index (WQI) and applying statistical approaches: principal component analysis (PCA) and cluster analysis (CA), to explore the relationship between anthropogenic activities and environmental variables. From the results obtained, it was seen that the WQI was highly correlated with the activities along the river bank. Human disturbance has severely degraded the water quality and ecosystem integrity, thereby depleting water resources. In addition, we speculate the significant decreasing trend between upstream and downstream of the Pahang River. Thus, serious mitigation steps should be proposed to protect our valuable resources.