This chapter attempts to establish whether certain assumptions underlying a co-operative undertaking to develop an international river for mutual benefit of the participating countries are, in fact, borne out by the resulting terms of agreement. Although they embody numerous qualifications which are subject to interpretation, in the main the International Joint Commission principles were directed toward realizing through co-operative development economies which would not be possible through independent action. When the Columbia River Treaty and its various economic consequences are viewed with the benefit of hindsight, there seems little to commend it in terms of realizing, through co-operation, economies unavailable to each riparian independently. The matter of efficiency in the design and operation of the Columbia hydro system was sacrificed to the goal of reducing the influence of the federal hydro system in the power program of the Pacific Northwest.