Several state-of-the-art models are available for analyzing water quality conditions in complex reservoir systems for a given set of operational conditions. Some of these models can even make operational decisions regarding proper gate regulations to obtain a desirable water quality condition at a dam site for a given set of flow conditions. HEC-5Q, Simulation of Flood Control and Conversation Systems (Including Water Quality Analysis) computer model, has the unique capabilities to accept user-specified water quality needs system-wide and to decide how to regulate the network of reservoirs. The decision criteria are programmed to consider flood control, hydropower, instream flow (municipal, industrial, irrigation, water supply, fish habitat) and water quality requirements. The model use a linear programming algorithm to evaluate the 'best' operation of multilevel intakes at each reservoir in the system. The user may select to operate the system for a balanced reservoir pool operation and its associated water quality or to allow for a modified flow distribution between reservoirs to improve the water quality operation. HEC-5Q has been applied to the 10,000 square mile (26,000 square kilometer) drainage area of the Sacramento River System. The Sacramento system includes two tandem reservoirs, three parallel reservoirs and 400 miles (640 kilometers) of stream channel network.