and the next morning found no difficulty in plowing the land. With 

 that first furrow began the irrigated agriculture of the intermoun- 

 tain region, which is the foundation of the greater part of the 

 prosperity of the valleys to-day. 



PEOSPEKITY THKOUGH lEKIGATION 



This prosperity is made possible only through the union of the 

 fertile soil and the life-giving water from the mountains. Great 

 depths of snow accumulate in the high ranges in the winter. Then 

 through the spring and early summer the snow melts slowly, fur- 

 nishing a great volume of water to the valley below. Later the 

 earth yields its stored supplies through springs and wells. Three 

 per cent of the 185,000,000 acres within the intermountain region 

 is cultivated — approximately 5,500,000 acres, of which 70 per cent 

 or 3,850,000 acres, is irrigated. Each year this irrigated land pro- 

 duces crops worth apj)roximately $174,000,000. 



RELATION OF FORESTS TO WATER FLOW 



In a sense it is true that this water resource is so closely related 

 to the climate and the characteristics of all mountains that man can 

 never destroy it nor forests influence it. As long as the mountains 

 stand, their cold heights will continue to accumulate great masses 

 of snow, which the summer sun will melt and send down to the 

 farms. Summer storms will continue to gather around the moun- 

 tain crests, adding to the flow of the canyon streams. The amount 

 of water which falls in the mountains can not be changed essentially 

 by man. Nevertheless, man can do a great deal to determine whether 

 the water shall flow gradually to the valleys and build up the farms 

 and industries there or rush down in floods to destroy the very 

 prosperity it might build up. 



If the mountain vegetation is removed by fire, by destructive 

 lumbering, by excessive grazing, or b}^ any other means, erosion and 

 floods follow. Showers cut the unprotected earth away and make 

 steep-sided channels through which even the normal spring freshets 

 from the gently melting snow rush with great violence, carrjdng 

 along mud, gravel, and stone, clogging irrigation ditches and canals, 

 filling reservoirs, and doing much damage. With the heavier storms 

 of midsummer, destruction comes out of the mountains in the form 

 of floods, carrying great bowlders, whole trees, and tons of earth, 

 rock, and. gravel, to spread over the farm lands in the valleys below. 

 These storms destroy irrigation works, bridges, highways, and por- 

 tions of towns. They even involve the loss of human life. In 1923, 

 for example, floods from a half hour's thunderstorm in northern 

 Utah did damage in excess of $150,000 to fields and towns and killed 

 nine persons. In this same region, severe floods occurred again in 

 1930 destroying ranches, homes, highways, and stretches of railroads. 



Even partial destruction of the vegetation on the mountains (not 

 to be confused with scientific harvesting of timber and forage crops 

 as conducted on national forests which insures protection of the 

 watersheds) means long-continued losses that amount to a great 

 deal in the aggregate. The retaining of dams and great reservoirs 

 becomes impossible on streams subject to floods and carrying great 



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