Water quality is an essential component in effective water management, specifically in the reservoir planning. Therefore, this study aimed to determine the water quality of the Malang Suko Reservoir, Malang Regency, Indonesia, by examining temperature, pH, Dissolved Oxygen (DO), Chemical Oxygen Demand (COD), and Biochemical Oxygen Demand (BOD5). To achieve this goal, the Dynamic System approach for reservoir management was employed, and the software used for water quality modelling was the System Thinking Educational Learning Laboratory with Animation (Stella). The analysis considered several contributing factors, such as settlements, agriculture, and temperature. The results showed that the water quality status of the Malang Suko Reservoir was moderately polluted. Therefore, several scenarios for managing the inflow of waste into the reservoir were suggested, with the role of the community being the most crucial.