196 THE FUTURE OF ARID LANDS 
compasses also saline waters in interior portions of the west. 
Improvement of these interior waters will enable not only certain 
new uses but also certain reuses. At present, costs of sea water 
conversion run upward from $450 per acre-foot of usable water 
yielded. It would of course be desirable to reduce this unit cost if 
possible to do so. At the same time the present cost is not too much 
above the sum needy communities are willing to pay; the city of 
Colorado Springs recently offered $350 an acre-foot for water 
presently being used for agricultural purposes. 
Many cities are learning they no longer can be profligate in 
their consumption of limited water resources, even in times of 
normal precipitation and storage. They are encouraging or even 
requiring their residents to be more economical in water use and 
are becoming more rigid in enforcement of regulations governing 
the water use by industrial plants. States are inclining more and 
more toward requiring treatment of industrial waste and sewage 
so as to improve waters that are subject to reuse. 
In the field of agriculture, great promise lies in research to 
discover the minimum quantities of water required to produce 
maximum crops. The Department of Agriculture and the Land 
Grant Colleges have made rather substantial progress in this field. 
I for one will be pleased when the laboratory experiments and 
limited field tests have been expanded into general application of 
the principles, and the results are known. Our irrigation districts 
and public authorities can do much to educate farmers along the 
lines of voluntary water conservation which is in their own in- 
terest. 
A somewhat related thought is that by persuasion, and perhaps 
ultimately by law, farmers must become convinced that parallel- 
ing canals, competing irrigation districts, and excessive individual 
water applications are luxuries the nation cannot afford. 
Operators of storage reservoirs, among whom the Bureau of 
Reclamation is the largest in the United States, have only 
scratched the surface of the subject of reservoir evaporation. 
Means of reducing evaporation are in the experimental stage. We 
are actively interested in the principle of using polar compounds 
which have the effect of a film on water surfaces. Household 
