4- Miscellaneous Circular 47, U. S. Dept. of Agriculture 



prairie schooners out of the mouth of Emigration Canyon to a halt- 

 ing place in what is now the center of Salt Lake City. That very 

 afternoon they unslung their plows, hitched up their teams, and 

 started to turn a furrow. The soil was dry and baked, however, 

 and the attempt was unsuccessful. So turning aside the waters of 

 the small stream now known as City Creek upon the sun-baked 

 earth, they let it soak over night and the next morning found no 

 difficulty in plowing the land. With that first furrow began the irri- 

 gated agriculture of the intermountain region, which is the founda- 

 tion of the greater part of the prosperity of the valleys to-day. 



PKOSPERITY THROUGH IRRIGATION 



This prospertiy 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. Of the 61,840 

 farms in the intermountain region, 50,025 are irrigated — approxi- 

 mately 4,500,000 acres. Irrigated land amounts to TO per cent of the 

 improved farm lands of the region. Each year this irrigated land 

 produces crops worth approximately $140,000,000. 



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 mountain crssts, 

 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 in- 

 dustries 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 by 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, carrying 

 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 portions of towns. They even involve the loss of human life. 

 In 1923, for example, floods from a half hour's thunderstorm in 

 northern LTtah did damage in excess of $150,000 to fields and towns 

 and killed nine persons. 



Even partial destruction of the vegetation on the mountains means 

 long-continued losses that amount to a £reat deal in the aggregate. 



