Will the water demands of the apparently unstoppable population increases of the ever-exploding cities of America's Southwest ultimately be a factor in limiting that expansion? Historically the "Field of Dreams" phenomenon has ruled the day: the suburbs have sprouted and the water to keep them green has arrived. Are times changing? What happens if the old patterns continue to prevail?

We conclude that in the long term, it is unlikely that population growth in the western United States will be constrained by physical limits in water supply. Even if reallocations to growing cities and suburbs from other sectors (agriculture and the environment) are blocked and global warming alters precipitation and runoff patterns, desalination of ocean water remains a potentially bottomless well, assuming environmental impacts on our shorelines, oceans, and climate can be mitigated and costs reduced.