324 THE FUTURE OF ARID LANDS 
disputes over conclusions developed when the Bureau of Reclama- 
tion appraised the water situation in southern Texas and con- 
cluded that a $1.1-billion investment in a canal plus a $too-million 
annual operating expense would ultimately increase the gross 
annual income of the area by $6 billion over the present income. 
Not many have denied the value of that water. At the next level, 
when a water-short community 1s deciding whether to encourage 
agriculture or manufacturing there will be a considerable argu- 
ment and permanent uncertainty over the decision. At the lowest 
level, when an individual farmer, for example, is deciding which 
crop to grow or whether to put an additional acre-foot on his pres- 
ent crops, there is very little scientific certainty and a great possi- 
bility for error. In fact, farmers, being in general poor at cost 
accounting and not having the facts to begin with, very frequently 
make other than optimum choices. Depending on the purpose of 
the compiler, water values may be based on gross income, on net 
profit, on payout period, on total employment, even on esthetic 
values, among other things. In the United States, where under 
scientific management net profit usually controls the decision, 
there are not enough available experimental data on the physical 
results of water use to set a proper value on it. What is needed is 
a careful study by economists and engineers of the value of water 
used for various purposes and under various conditions; and es- 
pecially if irrigation is to continue a major user of water, studies 
are needed by agronomists and agricultural economists to place a 
definite value on water used for specific agricultural purposes. 
Water Re-use 
In general, topics of competitive prices, transportation costs, 
markets, and values have been discussed in the preceding section 
on demineralization in order to provide an orientation for the de- 
mineralization costs there cited. Those factors apply equally well 
to other methods of securing additional water sources such as 
water re-use. 
The re-use of water in the United States is much more common 
than most people realize. In the United States 70 million people 
drink from sources which are used also for sewage disposal. Prob- 
ably 69,990,000 of them are not aware of it. A properly designed 
