NATIONAL FORESTS AND THE WATER SUPPLY 



1511 



abundant water supply is shown by the examples of and abundant water supply by the National Forests. So 



Los Angeles and San Francisco, the first of which has important is this function of the Forests that many com- 



considered it worth while to spend some $25,000,000 to munities have entered into co-operative agreements with 

 bring water 



f 1 o m Owens 

 Valley on the 

 east side of the 

 Sierras across 

 250 miles of 

 desolate and 

 rtigged coun- 

 try ; while San 

 Franc isco is 

 going back igo 

 miles into the 

 fastnesses of 

 the Sierras at 

 an est imated 

 cost of %77r 

 000,000 in order 

 to get its sup- 

 ply from the 

 famous valley 

 of the Hetch 

 Hetchey. 



Some 732 

 western towns 

 and cities, with 

 an a g g regate 

 population of 

 2,265,000, de- 

 pend on the 

 National For- 

 ests for their 

 domestic water 

 supply. This 

 does not in- 

 elude, of 

 course, ranches 

 and small set- 

 tlements equal- 

 ly d e p endent 

 on the Forests, 

 nor the towns 

 and cities 

 securing their 

 domestic water 

 ( r o m streams 

 and under- 

 ground sup- 

 plies which are 

 at some dis- 

 tance from the 

 F o r e s ts, but 

 which rise from 

 sources within 

 them. Denver, Colorado ; Salt Lake City, Utah ; Los 





THE DESERT BLOOMS 



With and without— a striking illustration of the transformation worked by the application of 



water. The dry land outside of the fence on the Minidoka Reclamation Project is a sagebrush 



desert; that inside, a fertile field of alfalfa. . . ,„ _. , , , 



Lower.— An apple orchard on the Boise Project of the Reclamation Service in Western Idaho on land 



formerly covered with sagebrush. 



Upper.- 



the Forest Ser- 

 vice for the 

 better protec- 

 tion of the 

 w a t e r s h eds 

 from which 

 they get their 

 supplies. 



Perhaps the 

 most obvious 

 relation that 

 exists between 

 forests and 

 water is the 

 tendency of the 

 tree cover to 

 check erosion. 

 The leaves and 

 branches of the 

 trees prevent 

 the rain from 

 beating upon 

 tb.e soil as it 

 does in the 

 open ; the cov- 

 er which they 

 .ilford delays 

 the melting of 

 snow in the 

 -pring ; the up- 

 per layers of 

 the forest soil 

 act as an 

 enormous 

 sponge that ab- 

 sorbs large 

 i| u a n titles of 

 water which in 

 turn are passed 

 DU to the great 

 r e s e r voir of 

 mineral soil 

 I icneath ; and 

 finally, the sur- 

 face cover of 

 stumps, fallen 

 twigs, branches, 

 and even whole 

 trees acts as a 

 mechanical ob- 

 s t r u c tion to 

 prevent rapid 

 run-off. The 



surface run-oft' from forest areas is less both in total 

 Angeles, California, and Portland, Oregon, are conspicu- amount and in velocity, than that from similarly 

 ous examples of large cities which are insured a pure situated unforested areas. The steeper and more rug- 



