To achieve the goal of cleaning river water, several pollution control actions had been enforced by the Environmental Protection Bureau of Taichung City in recent years. It included industrial wastewater and municipal sewage discharge inspection, wastewater discharge permit evaluation and river water quality monitoring program. In the river water quality monitoring program, periodic river water sampling from 23 monitoring stations on 2 rivers and 8drainage systems have been performed. Analytical data are used to evaluate river pollution index (RPI) and water quality index (WQI). These indices are also served as the criteria for pollution control reinforcement.