THE LIMITED WATER SUPPLY OF THE ARID REGION 489 



of tlie land can be reclaimed excites comparative!}' little interest. 

 Public sentiment is now concentrated on the question as to how the 

 relatively small quantity of Avater can be conserved for the largest 

 use. 



That the available water supply is relatively small need excite no 

 surprise. The mountain catchment area is small, the great moun- 

 tain masses, though impressive, covering but a small part of the arid 

 land. An erroneous idea is largely ])revalent that mountains abound 

 on every hand, and that the rain and snowfall upon these must neces- 

 sarilv l)e large. We hear of the large number of mountains rising 

 to heights of 13,000 or even 14,000 feet throughout the ^^^est, but the 

 fact must not be lost sight of that these mountains rise from a base 

 which, as a whole, is at a considerable elevation above tide. Mount 

 \Vashington, in New Hampshire, is not quite 6,300 feet high, while 

 Pikes Peak, Colorado, is over 14,000 feet; but the former rises from 

 a couritry whose general elevation is but little above sea-level, while 

 in the case of the latter the surrounding ai'eii, as a wliole. stands at 

 a height of from 5.000 to 6,000 feet. The State having the greatest 

 range in altitude (Calilbrnia) has onl}' about 1,760 square miles at 

 an elevation of over 10,000 feet, out of a total of al)out 160,000 

 square miles; in other words, the high, sharp peaks which dominate 

 the landscape and form the catchment areas for the streams are of 

 relatively small extent when com[)ared with the great open valleys 

 where water is needed. 



From all the peaks, however, little streams issue, carrying water 

 throughout the year. In I\Iay and June these streams gradually 

 swell to torrents, as the}' are i'ed by the melting snow. Descending 

 the steep slopes, they ]iass from the foothills out among the })]ains, 

 and their waters rai)idly shrink and even disa})pear. Thus it is that 

 following down a stream of considerable size in the mountains one 

 .soon readies the point wliere it has attained its greatest volume, and 

 beyond this one i»asses successively through open valleys wliere the 

 volume of water is noticeably less, and finally may reach a point out 

 on the plains where the bed is occupied merely by pools fed by occa- 

 sional storms or l)y slow percolation from underground. Under the 

 brilliant sunlight the hot winds have drunk up the cooling waters 

 from the heights. 



These littb^ streams have from prehistoric times been usa] in agri- 

 culture. We find thi-ougbout a great part of the ai'id West the ruins 

 of ancient towns, and even of irrigation canals of considei'able size, 



