The dictionary defines river basin as the area of land drained by a river and its branches, or tributaries, and traces its usage in English back to the last quarter of the 19th Century.' If the term itself entered the language without demur long ago, disagreement over the scope of activities that may be centered on the river basin has raged ever since.' In part this stems from different perceptions of the basin's physical unity and of its potential as a unit of resource management. These varying perceptions form the substance of the present article.