16 CIR. 211, U. S. DEPT. OF AGRICULTURE 
try, therefore, will depend upon the amount of water 
and the manner in which it flows from the mountains. 
The vegetal covering has a very decided influence 
on run-off. For this reason Congress made the pres- 
ervation of conditions favorable to stream flow one of 
the principal objects in the establishment and admin- 
istration of the national forests. 
A well-kept forest is the best of natural soil holders. 
F-175334 
Yicure 6.—Heavy erosion following lumbering and fire 
Where there is no vegetation, particularly on steep 
slopes, there is nothing but the friction of the soil to 
keep water from following its habit of going downhill 
as fast as it can and carrying much of the soil with it. 
Forests and well-sodded pastures hold back.more rain 
water and more soil on steep slopes than denuded 
woodlands or overgrazed ranges. (Figs. 6, 7, and 8.) 
Along the streams within the national forests are 
Many sites suitable for power development. These 
are open to occupancy for such purposes and have 
the advantage of being on streams whose headwaters 
are protected. The Government does not permit the 
monopolization of power in any region or allow power 
sites to be held without prompt development. Utiliza- 
