14 
BULLETIN 654, U. S. DEPARTMENT OF AGRICULTURE. 
this valley also was irrigated by prehistoric peoples, remains of their 
canals still being visible. 
The climate is somewhat cooler than in Salt River Valley, the 
elevation being about 1,500 feet greater, and the seasons are shorter. 
Neither dates, citrus fruits, nor olives can be grown here, and the 
season is rather short for Egyptian cotton. Only the hardier vege- 
tables, such as cabbages and radishes, can be grown during the whiter 
season, and these are often injured by frosts, temperatures as low as 
8° F. having been recorded. Alfalfa furnishes much less winter 
pasturage than in Salt River Valley, its growth being distinctly 
checked during the winter months. On the other hand, the growth 
is not seriously checked during the midsummer season, as it is in Salt 
Fig. 4.— Temporary dam and headgate of irrigating canal, Gila River. 
River Valley and Yuma Valley, and the total jields of hay are prac- 
tically the same in the three valleys. 
The annual rainfall is approximately 10 inches, coming in two short 
rainy seasons, one in whiter and the other in midsummer. The rains 
are not considered beneficial to agriculture, and those coming in 
midsummer are distinctly injurious, frequently doing great damage 
to crops being harvested. Crop production depends wholly upon 
irrigation for its water supply. 
High mountains surrounding the valley modify the summer heat, 
making the climate agreeable and healthful. 
The leading money crops are alfalfa hay, wheat, and barley. More 
corn and oat- and less grain sorghums are grown here than in Salt River 
Valley. Deciduous fruits when properly cared for do well, especially 
apples, peaches, apricots, and plums. The codling moth, root rot, and 
