154 LANDS OF THE ARID REGION OF THE UNITED STATES. 
The time when the volume of available water furnished by any stream 
bears the least ratio to the demands of the growing crops is the most critical 
period in the cultivation of the soil where artificial irrigation is a necessity. 
This time, depending as it does upon the crops cultivated, the character of 
the soil, and the source of the water supply, whether from springs or from 
melting snows, differs in different localities. In the valley of the Virgin it 
occurs in June. 
At this time the river, though not at flood height, which occurs in April, 
carries a large volume of water, and, by reason of the source of this supply 
being in the rapidly melting snows of the Colob Plateau, is decreasing but 
slowly, and thus the amount available at this critical period bears a greater 
ratio to the flood of the stream than is usual in Utah. But little information 
has been obtained concerning the amount of water necessary to irrigate an 
acre. It is thought, however, to be much greater than in any other portion 
of Utah. 
KANAB CREEK. 
Kanab Creek rises in springs bursting from underneath the cliffs 
forming the southern boundary of the Pauns-a-gunt Plateau, and flows 
southward until it joins the Colorado River in Arizona. Small areas of 
arable land are found along its course after it has descended to an altitude 
of 7,500 feet, and thence until it passes beyond the boundaries of Utah. 
The largest area in one body is in Kanab Valley, at the foot of the 
Vermilion Cliffs. It is greatly in excess of the water supply, is at an 
altitude of about 5,000 feet, has a fertile soil, and requires but compara- 
tively a small amount of irrigation, The amount actually under cul- 
tivation in 1877 is placed by the best information attainable at 700 acres. 
The critical period in the cultivation of this area occurs in June. At 
that time the stream is falling rapidly, and crops have sometimes been 
seriously damaged. Estimates of the volume of water in the stream, 
made at different seasons and in different years, give 15 cubie feet per 
second as the flow in June. Some desultory attempts have been made to 
increase the supply by ponding, the canon through the Vermilion Cliffs 
