Regional water quality management models for river systems with multiple sources of pollution are reviewed. The optimal solution is analyzed from the point of view of comparing the efficacy of more intensive waste treatment by the individual waste discharger with the efficacy of increased upstream treatment. The value of upstream waste treatment to the individual discharger diminishes the further upstream one moves. A relationship for evaluating this trade off is presented. The alternative situations that might occur in a regional system are then analyzed. An application of the analysis to a hypothetical region is presented.