Due to financial constraints, water quality monitoring network design is an efficient way to manage water quality. The most crucial part is to find appropriate locations for monitoring stations. Considering the objectives of water usage, we evaluate existing water quality sampling stations of the Sefīd-Rūd River, located in the north of Iran, which has been used for irrigation and drinking water. There are several methods for assessment of existing monitoring stations such as Sanders method, multiple criteria decision making and dynamic programming approach (DPA) which DPA was opted in this study. The results showed that out of 21 existing monitoring stations, eight and seven stations should be retained on the upstream and downstream of the basins, respectively. Although the area of the downstream basin is larger than the upstream basin, the number of stations which was retained was less than upstream. This may mean that water quality of the downstream is more favorable than the upstream. Meanwhile the technique may be also suitable for optimization of the water quality network.