Water supply is an important contextual theme in programme of planned economic development. Using the Romanian example it is shown how increasingly heavy demands for water call for a more sophisticated approach to planning in each drainage basin, with measures to increase water storagesand reduce pollution. Such activity can also bring important benefits for navigation, flood control and hydroelectricity output. Substantial investment in multipurpose projects is now required by the economy which is, nevertheless, hardpressed to generate the financial and technical resources that are required. At the same time it is shown how the theme of water resource management, taken in historical perspective, can act as a theme for analytical regional geography. River navigation (backed up with schemes for flood control and hydroelectricity generation) constituted a powerful stimulus in the nineteenth century. Hydroelectricity became a more significant factor after the First World War but construction of major projects has been accelerated by a multi-purpose approach, strenghthened recently by the psychological impact of the 1970 and 1975 floods. Finally, with major rivers forming long sections of Romania's international frontiers', relations with neighbouring countries must be considered a critical factor in the development programme.