235 



CHAPTER XXX. 



FORESTRY AND ITS RELATIONS TO THE WATER SUPPLY OF 

 SOUTHERN CALIFORNIA. 



By A. H. Koebig, Consulting Engineer. 



It is a common belief that the forests upon the watershed of any 

 river have a great influence upon the water supply in that river, al- 

 though, this belief being a general one, the facts must be enumer- 

 ated in order to understand the reason why we should plant forest^ 

 upon watersheds to protect our water supply. 



The forests of Southern California are situated almost exclusively 

 upon the high mountain watersheds of the streams. The north side 

 ot the mountains produces a very much denser growth than the South- 

 ern exposure. On the northern slopes at an altitude of about 3,500 

 feet above sea level we find the black oak, the yellow and sugar pines, 

 the fir, cedar, hemlock and others of the family of the needle-bearing 

 trees, also a luxurious growth of underbrush, consisting of ferns and 

 mosses, while the southern exposure and the lower altitudes of the 

 northern slopes only produce a spare growth of wild plum, scrub oak, 

 manzanita, sage brush, grease wood and others of that class. 



Our forests in the mountains have for many years past suffered 

 by the continuous cutting of the trees for fire wood and lumber, and 

 by frequent and extensive forest fires; also the herding of many 

 thousands of sheep has destroyed the undergrowth and many trees, 

 until it is almost impossible for the forests to recover, unless artificial 

 means are employed to assist the same. This denuded condition of 

 the mountains which constitute the natural watershed for our rivers 

 and creeks has a most damaging influence on the water supply delivered 

 to our valleys. 



It is a well established fact that wooded mountains have a greater 

 power to attract the clouds saturated with water and cause precipita- 

 tion of the same. The forests on the mountains also moderate the 



