Many of the freshwater problems of the 21st century will arise from increasing demands for water generated by rapid population growth, urbanization, industrialization and irrigation needed to satisfy the additional demand for food. The increased demand for water is being exacerbated by the excessive pumping of groundwater aquifers, some of which hold ancient or fossil’ water, and by the deteriorating quality of both surface and groundwater supplies. When it comes to the role and the fate of water resources in semiarid environments, despite the many differences socially, politically, culturally and economically among regions around the globe, many similarities actually exist. This article will examine in some detail how these issues manifest themselves in three geographic regions: the Western USA, especially the Central Valley of California; northwest Mexico, especially the Comarca Lagunera and Costa de Hermosillo; and the Aral Sea region of the Central Asian Republics of the Soviet Union. These case studies show that, in order to improve water management and use patterns, we must learn from past experience, utilize available information effectively, and avoid making the same old mistakes. One lesson from the past is very clear: without appropriate policy and institutional adjustments, no technical or engineering fix will succeed.