TRRIGABLE LANDS OF THE COLORADO DRAINAGE. ail 
permanent locations being in the southwestern part, and in the Uinta Valley 
at the north. Information concerning its agricultural resources is limited, 
being confined, except in relation to the localities before mentioned, to data 
collected by the geographical and geological parties of this survey. Many 
of the streams have been visited but a single time, and different streams at 
widely different dates, during a field season. Often the exigencies of the 
survey prevented as close an examination into the flow of water, and the loca- 
tion and character of the soil of the arable tracts, as was desirable ; yet, on 
the whole, it is thought that the data collected can be relied upon as a very 
close approximation. 
The climate of the basin is one of extreme aridity. The prevailing 
wind is westerly. The high plateaus and mountains forming the western 
rim of the basin force these winds up to an altitude above the sea of over 
10,000 feet, and thus act as great condensers to deprive them of their 
moisture. Flowing down from the higher lands into the warmer regions 
below, their capacity for absorption is increased, and during the greater 
portion of the year the winds abstract from rather than add to the humidity 
o the actual amount 
of precipitation of moisture within the basin. Below an altitude of 7,000 
of the lower altitudes. But little is known concernin 
feet it is very small, probably not over an average of 5 inches yearly. At 
greater, probably reaching 24 inches, but this is 
higher altitudes it is much 
mostly during the winter months and in the form of snow. 
The elevation of the region under consideration is from 2,500 feet to 
11,500 feet above the sea, thus giving great range in temperature. In the 
valleys of the extreme southwestern portion an almost subtropical warmth is 
experienced, and the different valleys containing arable lands we pass from 
these by insensible gradations to those where frosts occur during every 
month in the year. Generally, the limit of successful cultivation of the soil 
is below 7,000 feet. . 
In this portion of Utah irrigation is essential to agriculture. If all 
the single acres it is possible to cultivate without artificial irrigation were 
ageregated, I do not believe the sum would reach one-fourth of one square 
mile, and every foot of this meager amount is irrigated naturally. Springs 
are of infrequent occurrence. The great source of the water supply is the 
