88 MISC. PUBLICATION 9 0, U. S. DEPT. OF AGRICULTURE 



Much of this is in undeveloped territory on the Green River water- 

 shed. 



In a great many irrigation projects the water is diverted directly 

 from the streams into irrigation ditches and onto the land. This 

 requires a steady stream flow far into the growing season for late irri- 

 gation. Frequently all of the high water in the spring can not be 

 utilized to good purpose, and in some cases storage reservoirs have 

 been constructed to make available this surplus water as well as 

 that which would otherwise go to waste during the fall and winter. 



Considerable irrigation water comes from pumps and flowing wells. 

 The well supply depends largely upon the amount of water taken 

 into the ground at the source of the watersheds. 



Figure 45. — Irrigated crops are supplied with water from the mountain watersheds. 

 Protection of the watershed is essential for maximum regularity in stream flow 



WATER FOR THE GENERATION OF POWER 



The most economical generation of water power requires a steady 

 stream flow throughout the year, which is fostered by the main- 

 tenance of the vegetative cover on the watersheds. The sustained 

 output of power plants depends upon the period of minimum flow. 

 Reservoirs are often used to equalize the flow and eliminate the low 

 point during the fall and early winter, but their construction adds 

 to the initial and maintenance costs. 



THE PROTECTION OF WATERSHEDS 



The limited amount of water available and its many direct and 

 indirect uses in the home and in the industrial and agricultural life 

 of Utah make water conservation one of the foremost problems of 

 the State. It has already been pointed out that water is the limit- 

 ing factor in agriculture. Utah has many million acres that could 



