Often several cities discharge their sewage into a single river. Such cities are concerned with the water quality of the river as it flows past them and with the costs associated with treatment. A utility function for each city describes the trade-offs. Preferences often conflict: the cities downstream wish that those upstream would treat their waste more intensively. Ambient conditions in the river are uncertain but can be expressed in terms of probability densities. 

The paper describes approaches to finding admissible solutions to the multi-interest-group water resource problem using Paretian analysis and optimal control theory. An example is solved, and extensions are discussed.