THOMAS B. NOLAN 61 



ment of the nation, he considers that "all our other water problems 

 are problems of shortage due to geographic and time variations, which, 

 important as they are, can be reduced to problems of economics. Eco- 

 nomic problems gradually become solved by the play of forces in- 

 herent in the market place. Water will be used in those places and for 

 those purposes which can best afford to bear the cost under prevailing 

 conditions." ^^ 



Leopold's conclusion is in effect another way of stating that we are 

 now able to solve our water problems, not by curtailment of use or 

 other restrictive measures based on possible exhaustion, but by utiliz- 

 ing our knowledge of the hydrologic cycle gained through extensive 

 research over past years, and our capacity to transport or regulate 

 water on a scale vasdy greater than in the past as a result of tech- 

 nologic advances. Our concern is not with running out of water that 

 is needed to accomplish certain desirable or necessary things, but with 

 whether the expenditure of labor and materials is justified by the re- 

 sults to be obtained. Use, rather than restrictions on use, controls our 

 thinking. 



I believe it is also true, as was suggested in the discussion of min- 

 eral raw materials, that we have by no means exhausted our capacity 

 to increase the amount of water available for use. From the knowl- 

 edge gained through research into particular segments of the hydro- 

 logic cycle, there are good grounds for believing that the usable frac- 

 tion of the water that reaches the earth as rainfall can be somewhat 

 enlarged over the one-fifth now considered to be the maximum. Cur- 

 rent studies on the principles of evaporation, for example, are greatly 

 increasing our knowledge of the relative importance of the factors 

 that affect the process; ^^ with this increased knowledge comes the 

 ability to influence one or more of them in a way to decrease current 

 evaporation losses, such as the experimental work now being done on 

 the use of a mono-molecular film of a nonpermeable solid on the sur- 



2* Luna B. Leopold, op. cit., p. 6. 



25 Water-loss Investigations: Lake Hefner Studies, Technical Report (U.S. 

 Geological Survey Prof. Paper 269, 1954), 158 pp. Water-loss Investigations: 

 Lake Hefner Studies, Base Data Report (U.S. Geological Survey Prof. Paper 

 270, 1954), 300 pp. G. E. Harbeck, Max Kohler, G. E. Koberg, and others, 

 Water-loss Investigations: Lake Mead Studies (U.S. Geological Survey Prof. 

 Paper 298), Washington, 1958. 



