The consequence on cost and water quality of discharging waste-water effluent through outfalls spaced along a river is examined. Compared to the conventional one-outfall case the effluent from a plant discharging through several outfalls can be of lower quality and still not violate stream standards. Thus the reduced cost of treatment can compensate for the added cost of the more elaborate transport system. A model of the stream characteristics based on the Camp-Dobbins equations was combined with a model representing the costs of water treatment and disposal. An algorithm has been developed and programmed to find the minimum cost configuration for any set of water and economic conditions. (Modified author abstract)