THE NATIONAL FOKESTS OF IDAHO 



13 



Table 5. — Number of livestock actually grazed on national forests of Idaho, 



season of 1924 



North Idaho 



South Idaho 



Forest 



Cattle 



and 



horses 



Sheep 

 and 

 goats 



Forest 



Cattle 



and 



horses 



Sheep 

 and 

 goats 







15, 701 

 150 



768 



33, 876 



4, 831 



2,449 



6,360 



Boise --. 



4,804 

 24, 865 

 18, 860 



7,957 



2,262 

 16, 128 

 19, 402 



6,238 

 15, 767 



8,037 

 18,049 

 11, 194 



118, 287 





126 

 5 

 6,113 

 508 

 31 

 255 





92, 517 





Caribou 



Challis 



233, 936 





65, 378 



Pend Oreille. 



Idaho _. . 



84, 015 



St. Joe 





84, 031 





Minidoka 



75, 151 





109, 625 

 56, 030 





7,038 



64, 135 



Salmon. .. . . . . 





Sawtooth 



Targhee.. .__ . . . 



200, 857 

 192, 410 





Weiser 



Total, south Idaho 



48, 199 





153, 563 

 160, 601 



1, 360, 436 

 1, 424, 571 









WATERSHED VALUES 



One of the basic purposes for which the national forests were es- 

 tablished was the protection of the watersheds. Water is of vital 

 importance in Idaho for irrigation and the development of hydro- 

 electric power, to say nothing of domestic and municipal use. Vir- 

 tually all the streams of importance for irrigation or for power 

 gather their volume on the high, forested slopes within the national 

 forests. Of the 42,106 farms in Idaho, 25,283, or 60 per cent, are 

 irrigated, and approximately 55 per cent of the improved land on 

 these farms is watered. Investments totaling $91,000,000 have 

 been made in irrigation works. It is also estimated that these 

 streams are capable of generating at least 2,000,000 horsepower. 

 These values are not confined to Idaho alone, for just as Idaho uses 

 water that originates outside of its borders on the head of the Snake 

 River in Wyoming, so it passes on to Oregon and Washington vast 

 quantities of water to be used in irrigation and power development 

 in those States. 



Although it is true that no mistreatment of the mountain water- 

 sheds could ever wholly destroy this resource, nevertheless a large 

 part of its value might readily be wiped out if the cover of timber 

 and herbage were removed. Such destruction of values might come 

 about in many ways. The most spectacular, of course, is floods, 

 which, rushing out of the mouths of the canyons where the water- 

 sheds have been denuded, spread disaster over the fertile farm lands 

 below. Persistent erosion in streams rising on barren watersheds 

 is even worse, because it continues year after year unless the water- 

 shed cover is restored. Such streams invariably carry with them, 

 even after normal storms, surprising quantities of silt, sand, and 

 even gravel and rock, which make the problem of reservoir and canal 

 maintenance very difficult. Operating costs on the irrigation and 

 power projects are increased to a remarkable degree, and may become 

 so serious as to make the projects entirely unprofitable. In addition, 

 destruction of the cover on mountain watersheds tends to bring about 



