436 A NATIONAL PLAN FOR AMERICAN FORESTRY 



ponderosa pine near the headwaters. Paria was first established in 

 1871; by 1884 it had grown to a community of 107 permanent resi- 

 dents, all living on irrigated farms along the river. Floods, beginning 

 in 1885, have channeled the valley bottom. The shifting bed of the 

 river is now only a sandy wash, in some places a quarter of a mile 

 wide. At Paria there have been no permanent residents since 1925, 

 and the land still arable does not exceed 60 acres. At Henrieville 

 and Cannonville, two of the three remaining settlements on the river 

 approximately one third of the land capable of cultivation in 1880 

 has been cut away. The third settlement, Tropic, has suffered 

 heavy, but unestimated, losses of farming land. 



Kanab Creek, near Kanab, Utah, further demonstrates the effect of 

 floods and erosion. This stream began to erode its bed about 14 

 years after the settlement of Kanab in 1870. It has continued to 

 entrench until the stream bed in places is now at the bottom of a 60- 

 foot gully 200 to 300 feet wide. The gullying extends through the 

 woodland, which covers rather large areas of the watershed above 

 Kanab, to the heads of tributaries in the mountain-brush type, which 

 now have new channels 4 to 6 feet deep. The eroded material has 

 been carried downstream, filling the Kanab Reservoir with silt and 

 contributing to the silt load of the Colorado River. 



WATERSHED-PROTECTION REQUIREMENTS 



That the accelerated erosion in southern Utah and adjacent States 

 is not due to climatic change alone is evidenced by the fact that the 

 channeling did not start in all valleys at the same time. In some 

 valleys it is much more recent than in others, and a few valleys are 

 still uneroded. 



The greatest damage caused by controllable factors to plant cover 

 as a protection for watershed values on the Colorado River has come 

 from overgrazing, fire, and excessive timber cutting, named in the 

 descending order of importance. Nearly all the lands of the basin 

 have value for grazing or timber production or both and are subject 

 in varying degrees to damage by fire. Adequate watershed protection 

 in the basin, therefore, requires proper range and timber management 

 and fire protection. Research results indicate the desirability of 

 controlling grazing, timber cuttings, and fire so as to make possible the 

 maintenance of a plant, litter, and soil cover approximately equal to 

 that which would be brought about under complete protection from 

 use and fire. 



Especially on forest areas at lower elevations, restoration of cover 

 is essential. Range research of the United States Forest Service indi- 

 cates that where soil and moisture conditions are favorable and a seed 

 supply of suitable native plants is present, under careful management 

 the cover can ordinarily be restored on moderately depleted areas in 

 from 3 to 5 years. Where soil and vegetative depletion have reached 

 an advanced stage, artificial restoration will be necessary if a satisfac- 

 tory cover is to be reestablished within a reasonable period. This 

 would take the form of planting trees on the more favorable sites and 

 herbaceous plants on those somewhat less favorable. On the latter 

 sites establishment of forest trees is so uncertain and growth is usually 

 so slow that it is difficult to establish a stand of trees sufficient in itself 

 to afford the necessary watershed protection. 



