IRRIGATION REQUIREMENTS OF THE GREAT BASIN 29 
when the crop is harvested, there is a gradual decrease in transpira- 
tion from 12 pounds to less than 1 pound per day. 
As has been pointed out, conditions imposed on the farmer may 
prevent him from irrigating at the right time and with the proper 
quantity of water. When possible, however, water should be sup- 
plied as needed during the various stages of growth of the crops. 
To do this, there should be an adequate and dependable supply of 
water throughout the irrigation season. 
CONDITIONS INFLUENCING THE QUANTITY OF WATER 
REQUIRED FOR IRRIGATION 
Of the conditions influencing the quantity of water required for 
irrigation in the Great Basin, what may be termed permissible waste 
of water is by far the most important. As shown by many of the 
records of duty-of-water measurements herein tabulated, much 
larger quantities of water are diverted from streams and other 
sources of supply than can be utilized b} T the crops irrigated. The 
difference between intake duty and the actual water requirement of 
crops is made up of losses in the conveyance of water from the 
source to the place of use, unequal distribution over the surface of 
fields, the application of more water than soils can hold, causing 
deep percolation losses, surface run-off, and other more readily pre- 
ventable losses. It is estimated that fully half of the water annu- 
ally diverted for irrigation purposes within the Great Basin is thus 
wasted. Bark's estimate for southern Idaho, where irrigation con- 
ditions are somewhat similar, was 55 per cent loss exclusive of 
evaporation from soils. 
In order to ascertain the percentage of this waste water which may 
be conserved economically, it is necessary to determine the relation 
between such factors as the value of water and the cost of conserving 
it, the value of crops and the profits derived from them, and also the 
damage inflicted by waste water, but as these are all variables, it is 
not possible to reach any definite conclusion. It may be stated, how- 
ever, that the general trend is toward a more economical use of 
water, largely on account of the growing scarcity of water and its 
rapidly increasing value, as well as the increasing damage due to 
water-logging and the cost of drainage. To illustrate : In 1898 a 
water right under the Bear River canal system in northern Utah was 
worth $10 per acre ; 25 years later the same right was worth $100 per 
acre, and in that period the area of land served by a unit of water 
was much increased. Accordingly, waste which was permissible under 
conditions which prevailed in 1898 may not be justified under 1924 
conditions, and wasteful practices which may be permissible now are 
not likely to be allowed in the years to come. 
Withdrew exceptions, water for irrigation within the Great Basin 
is conveyed in earthern ditches. These are located for the most part 
on porous bench lands which absorb a large quantity of the water as 
it flows from the source to the place of use. This loss is greatly in- 
creased by the existence of too many canals. In many cases one 
canal could be made to serve the land which is now watered by from 
10 to 20 canals. If a dozen or more of these small, poorly built water 
carriers could be merged into one canal of proper construction and 
