NATIONAL FORESTS AND THE WATER SUPPLY 



1511 



abundant water supply is shown by the examples of 

 Los Angeles and San Francisco, the first of which has 

 considered it worth while to spend some $25,000,000 to 

 bring water 

 fiom Owens 

 Valley on the 

 east side of the 

 Sierras across 

 250 miles of 

 desolate and 

 rugged coun- 

 try; while San 

 Franc isco is 

 going back 190 

 miles into the 

 fastnesses of 

 the Sierras at 

 an est imated 

 cost of $77,- 

 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 

 from 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 

 Angeles, California, and Portland, Oregon, are conspicu- 

 ous examples of large cities which are insured a pure 



THE DESERT BLOOMS 



Upper.— 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. 



surface run-off 

 amount and in 

 situated unforested areas. 



and abundant water supply by the National Forests. So 

 important is this function of the Forests that many com- 

 munities have entered into co-operative agreements with 



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 

 the soil as it 

 does in the 

 open; the cov- 

 er which they 

 afford delays 

 the melting of 

 snow in the 

 spring; the up- 

 per layers of 

 the forest soil 

 act as an 

 enormous 

 sponge that ab- 

 sorbs large 

 q u a n tities of 

 water which in 

 turn are passed 

 on to the great 

 r e s e r voir of 

 m i n e r al soil 

 beneath ; 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 

 from forest areas is less both in total 

 velocity, than that from similarly 

 The steeper and more rug- 



