Losses from Misuse of Water 
In addition to the extensive losses from floods and sediment 
caused by water, there are significant losses of and to water 
as an agricultural resource. Much of the water resconsible for 
floed and sediment damages represents badly needed moisture lost 
through runoff from improperly managed cropland, rangeland, and 
forest land. Losses also arise from wasteful storage, convey- 
ance, and application of irrigation water, and from overpumping 
of ground water, 
Trrigation Water 
Of the approximately 190 million acre-feat of water annually 
diverted for irrigation, 50 million acre-feet wera lost through 
seaparze and evaporation in transit betwsan the point of diversion 
(reservoir, stroan, well) and the farm to be irrigated. Another 
25 million acre-fsst were lost between the margin of the field 
and delivery to the root zone of the crop. If only a third of 
the loss were prevented, the annual saving, at $2 per acre-foot, 
would amount to #50 million. The fact that only about 5 percent 
of the approximately 129,900 miles of canals and laterals are 
lined gives some indication of the scope of preventability of 
seepage lossese 
Obviously, water lost from seepage does not represent a total 
loss, since much of it becomes part of the ground-water supply 
and, with additional inputs, remains available for use. On the 
other hand, water lost from canals, laterals, and irrigation 
checks and furrows is the major source of the waterlogging and 
contributes to alkali accumziation. In addition to these losses 
by seepage, evaporation, and runoff, millions of acre-feet of 
water are lost annually through transpiration of phreatophytes 
(water-consuming plants of little economic value). 
Ground Water 
The over-all ground-water resources of the Nation are not being 
significantly depleted, but in localized arsas overdevelopment 
is a critical problem, Losses of ground water from overdevelopment 
primarily increase pumping costs, but if pumping exceeds rechargs 
for a considerable time, reduced yields and, in some arséas, 
abandonmant are the ultimate results, In the southern San Joaquin 
Valley of California, for example, the annual overdraft on ground 
water is 1 to 1.5 million acre-feet. Although only part of the 
losses from overpumping are agricultural, over half of the esti- 
mated 20 billion gallons of ground water pumped per day is used 
for irrigation and other agricultural purposes. 5/ 
S/ McGuinness, ©. L. 1951. The water situation in the United 
States, with special reference to ground water. U.S. Geol. Survey 
Cirs Iti ep. 26h. 
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