National Forest Resources of Utah 21 



The most destructive form of erosion is that resulting from heavy 



summer thunderstorms in the mountains and consequent floods. 



The dashing rain water runs rapidly over the unpro- 



Vegetation on tected ground, cutting little rills and becoming 

 duces Floods. " thick and muddy almost instantly. These muddy 

 rills running together form a thick mass that moves 

 with difficulty down the canyon bed, gathering behind it an immense 

 head of water. Banks are undermined, and rocks, trees, and tons 

 of earth are added to the tremendous moving, rolling mass that, 

 proceeding down the canyon, tears out evervthing in its course. 

 Finally, when the open land at the mouth of the canyon is reached, 

 the water spreads out with almost explosive violence, covering 

 fields and orchards, destroying everything that stands in its path 

 (fig. 14), and hurling here and there enormous rocks. Damage 

 amounting to many thousands of dollars has been done in Utah 

 by floods of this kind. It can not be claimed that proper watershed 

 protection is absolute insurance against such floods, for the rainfall 

 may be extremely violent. Nevertheless, there is abundant proof 

 that proper watershed protection does much to minimize the destruc- 

 tiveness of such run-off and in most cases will prevent the floods. 



The damage resulting from too rapid run-off is not confined to 

 the irrigated land in the valleys. The mountains themselves suffer. 

 The rich topsoil, developed by ages of decaying vegetable matter, 

 is washed away, leaving a barren and sterile suboil in which neither 

 trees nor forage develop normally. 



The same thing that has been said of irrigated farming applies 

 to hydroelectric developments. They become expensive and indeed 



Hvdroelec- v i rtuan y impossible on streams that are muddy or 

 tricdevelop- subject to violent fluctuations and floods. The 

 merits demand close relationship between irrigated farming, hydro- 

 Watershed Pro- electric developments, and the national forests is 

 tection. shown in Figure 15. 



Fire and overgrazing are the two great dangers to watersheds. 

 Overgrazing has been obviated through provisions for proper range 



Fire and Over- management, and fires of any size are extremely 

 grazing Destroy rare within these national forests. The average 

 Watershed area burned over annuallv during the nine vears 

 Values. f rom 1916 t0 1924^ inclusive, was 3,023 acres out of 



a total of 7.455,070 acres in the national forests of Utah. 



RECREATION 



Recreation is an exceedingly popular by-product of the national 

 forests. Save in very exceptional instances where scenic values are 



unique and outstanding, recreational uses are inci- 



Recreation Is dental to other forest uses. Timber is cut conser- 



Forest* By-Prod- vativel y> as sucn cutting keeps the forests in a highly 



uct . productive condition. Brush is disposed of on timber 



sales, usually through burning, because with it is 

 removed a very real fire hazard, and incidentally the forest floor is 

 left clean and neat. The national forests are grazed lightly and in 

 an orderly manner, not primarily to maintain the mountain meadows 



