430 A NATIONAL PLAN FOR AMERICAN FORESTRY 



in order to safeguard water resources more fully. Enough trees are 

 left in logging to afford satisfactory reforestation and to safeguard 

 watershed values. The subordinate vegetation in the forest is in gen- 

 eral improving under grazing regulation. Further strengthening of 

 the fire-control program will be necessary. Within the national 

 parks, grazing and timber cutting are not permitted and a satisfactory 

 watershed cover is being maintained except as it is depleted by fire. 



On the 966,000 acres of forest land within the unappropriated 

 public domain, conditions are far from satisfactory. Much of the 

 herbaceous and shrubby vegetation is heavily grazed. Fires are set 

 on these lands just as on private lands, exposing the soils to erosion. 

 This area should be given a status that will insure proper management. 



The situation on private lands, especially in the foothills is such 

 that the public should acquire about 10,000,000 acres in these drain- 

 ages, 5,000,000 acres of which is in commercial timber types and 

 5,000,000 acres in noncommercial forest types in the foothills. 



Approximately 75,000 acres of land in critical condition should 

 be planted to trees and another 100,000 acres seeded to herbaceous 

 plants in order to more effectively safeguard watershed values. If 

 practical methods can be developed for planting trees or shrubs on 

 the depleted foothill areas the reforestation program should be 

 greatly expanded. 



COLORADO RIVER BASIN 



The outstanding watershed problems of the Colorado River basin 

 are (1) supplying adequate water for irrigation, power, and domestic 

 use, (2) controlling erosion, and (3) reducing damage from local 

 floods. As is shown by figure 12, the basin includes portions of 

 California, Nevada, Arizona, New Mexico, Utah, Colorado, and 

 Wyoming. The perennial flow of the Colorado River and its main 

 tributaries originates almost entirely on the higher mountain areas, 

 nearly all of which are forested or above timber line. Most of the 

 sediment carried by the main river and its tributaries comes from 

 erosion of the lands at the lower elevations, which are largely non- 

 forested, or from the scouring out of channels. Large areas of for- 

 ested land, also, have soils that are readily eroded if the protecting 

 vegetative cover becomes depleted. The intensity of the scouring of 

 channels is greatly increased by the soil and other erosion debris 

 washed from slopes. Local destructive floods most commonly 

 originate at medium or low elevations, often on depleted forest areas. 



EXTENT AND WATERSHED-PROTECTION VALUE OF FORESTS 



Of the 242,000 square miles of the Colorado River Basin within the 

 United States about 70,422 square miles (45,070,000 acres), or nearly 

 29 percent, is forest land. Approximately one fourth of this is 

 occupied by coniferous forests, largley commercial timber, made up 

 principally of rather dense stands of spruce, white fir, or lodgepole 

 pine at the higher elevations and of more open stands of ponderosa 

 pine or Douglas fir, with an understory of herbs and shrubs, at 

 intermediate elevations. 



The aspen-brush type, predominantly aspen, occupies about one 

 tenth of the forest area. In this type undergrowth normally is fairly 

 dense, and small intermingled areas of brush and grassland occur. 



