The true desert, wherein the production of crops is wholly dependent
upon the artificial application of water, lies for the most part west
of the Rocky Mountains. Its estimated area, 900,000 square miles,
is probably slightly greater than that of the semi-arid region. An
accurate determination of the relative size of each, however, is not
possible until a comprehensive hydrographic survey has been completed.
Contrary to popular opinion, this region is not a vast wilderness,
desolate and unpromising. Between the mountain ranges lie many
beautiful valleys, through which flow numerous streams fed by melting
snows. Utah and Nevada contain large areas of sage-brush desert,
comprising what is known as the Great Basin, which has no outlet to
the sea, and is doomed to aridity by reason of the absence of living
streams. Millions of acres of desert now inhabited by the coyote and
the rattlesnake await only the coming of the engineer to wake to
teeming fecundity.
In one important respect the arid and semi-arid regions are alike, and
that is in the character of the streams. Almost without exception the
rivers of the West are erratic and “flashy” in flow, are subject to
long periods of drought and sudden and destructive floods. The full
utilization of these streams for irrigation and power necessitates
storage. In the control of floods, engineers have found their greatest
problem, and one whose solution has taxed the skill, imagination and
daring of twentieth-century genius.
[Illustration: WHEAT ON SHOSHONE PROJECT, WYOMING