Managing reservoir systems for economic efficiency requires maximizing total economic benefits over all water uses, time periods, and locations. This paper presents results derived from a basin optimization model that solves both multiple use and dominant use management objective functions. Application of the model to New Mexico's Rio Chama basin for the uses of river recreation, lake recreation, and hydropower indicates a negligible difference in system benefits between managing for multiple use and for a dominant use. However, there is a substantial difference in the distribution of water across reservoirs and economic benefits across uses. Results suggest that in basins where nonconsumptive uses are dominant, managers may have more latitude than previously believed in managing for dominant uses while still meeting a larger economic efficiency objective.¿ 1997 American Geophysical Union