PROTECTION 163 



development of power. The future development 

 of the entire region depends, therefore, upon a reg- 

 ular water supply. It is not so much the amount 

 of water as the manner in which it flows from the 

 mountains that is important. To insure this regu- 

 larity, the vegetative covering is an important fac- 

 tor. For this reason, Congress made the preserva- 

 tion of conditions favorable to stream flow one of 

 the principal objects in the establishment and ad- 

 ministration of the National Forests. 



Many of my readers who have lived out-of-doors 

 a great deal have learned by common observation 

 the simple problem of how the forest regulates 

 stream flow. Any one who has been in a treeless 

 region after a heavy rainstorm can recall how sud- 

 denly the streams swell and flood their banks, and 

 how soon these same streams return to their former 

 flow. On the other hand, a severe rainstorm in a 

 forested region will hardly have an appreciable 

 effect upon the streams. The difference is not very 

 hard to explain. In a treeless region there are no 

 natural obstacles which might delay or prevent the 

 raindrops from reaching the ground. The soil is 

 usually hard and dry, and the water runs off as 

 though from a gable roof. In a forest, we well 



