LUTHER GULICK 119 



speed, and cannot in fact remain on the ground, so many urban 

 "problems" do not exist until certain concentrations are reached, but 

 then become imperative and inescapable from that point on. Few 

 urbanization problems arise in a continuous and gradual intensity, 

 emerging by small fractions as each family is added to the com- 

 munity. They tend rather to emerge by major leaps, much as nerve 

 stimulation passes sharply from a range below the threshold of notice 

 into the range of violent response. This take-off situation is clearly 

 evident in dealing with water supply, though the point at which 

 broad community action becomes imperative varies greatly with geo- 

 graphical factors. 



While the amount of water which populations will use in urban 

 regions shows considerable elasticity depending on prices charged 

 and governmental controls,^ it is already evident that the scarcity of 

 water can become a limiting factor both for the location of certain 

 industries (and their employment potentials) and, possibly, also for 

 the further rise of urban populations in some regions. There have 

 been cases in history of great cities which have been abandoned pri- 

 marily because of the disappearance of water resources. But that 

 time is now passed. Today, when water is short, we don't abandon 

 the site, or restrict in-migration; instead we increase our efforts, and 

 find more water. While this will get more and more difficult in some 

 places, at least until demineralization becomes practicable, the indi- 

 cations are that water shortages will restrain population settlement 

 only indirectly by limiting industrial development and thus employ- 

 ment. 



The urban water problem is destined to arise in a new form in 

 some western states, where local water resources have been im- 

 pounded by great dams and completely budgeted for the indefinite 

 future for "export" and for agricultural uses. These water budgets 

 were drawn before the rise of urban concentrations near the water 

 sources, and will now create an artificial water shortage there. Such 

 budgets will surely be redrawn. In a democracy, no government can 

 long export water and leave behind thirsty voters. 



Air and water pollution. Here again we meet a unique urban situ- 



3 New York City Mayor's Committee on Management Survey, Report of 

 Engineering Panel on Water Supply (New York, 1951), Chap. II. 



