Canadian Forestry Journal, April, 1919 



159 



FLOODS AND EROSION — CAUSE AND CURE 



Samuel T . Dana, Assistant Chief of Forest Investigation, Washington. 



How any interference with the protective 

 cover of trees and other vegetation works to 

 the detriment of the water user is illustrated by 

 the history of a small stream on the Pike Forest 

 known as Trail Creek. This was originally a 

 clear stream confined to a narrow channel and 

 with comparatively little erosion. Gradually, 

 however, the character of the stream changed as 

 a result of heavy cutting on its watershed prior 

 to the creation of the National Forest and on 

 private lands included within the Forest bound- 

 aries, followed by a number of severe forest 

 fires. Floods became more frequent, erosion 

 , set in, the stream beds were widened, and their 

 bottoms began to fill up with sand and gravel 

 washed down from above. 



A Ranch Buried. 



In April, 1914, a heavy flood occurred which 

 wrought serious damage to a small ranch at the 

 mouth of the creek. Approximately 1 1 acres of 

 irrigated land, worth $40 an acre and includ- 

 ing nearly a fourth of the irrigated land on the 

 ranch, were buried under from 18 to 30 mches 

 of coarse gravel and rendered practically worth- 

 less. Furthermore, the flood filled up the irrigat- 

 ing ditches so completely and changed the 

 course of Trail Creek so markedly as to make it 

 impossible to continue the use of water from 

 the creek for irrigation without going to con- 

 siderable expense in the construction of new 

 improvements. In August of the next year a 

 heavy hailstorm resulted in another flood which 

 washed out several acres of hay land along 

 the creek bottom and ruined 16 tons or more of 

 hay worth $14 a ton. The same storm also 

 brought down an immense amount of gravel in 

 an ordinarily dry gulsh running through the 

 farm and piled this lYz feet deep against the 

 kitchen door. Altogether, the floods of these 

 two years damaged this one small ranch to the 

 extent of at least $600 and rendered approxim- 

 ately one-fourth of it practically nonproductive. 



Other examples of the damage resulting from 

 interference with the forest cover before the 

 creation of the National Forest can be selected 

 almost at random from the Mountain Forests 

 of the West. In the Sangre de Cristo Range 

 and the Greenhorn Range, in what is now the 

 San Isabel National Forest, in southern Colorado, 

 it is very noticeable that streams whose head- 



waters have been denuded to a considerable 

 extent of their protective cover have badly 

 eroded channels and are subject to great ex- 

 tremes in flow, with frequent destructive floods, 

 while no harmful effects of this sort are notice- 

 able on streams whose headwaters are well 

 timbered. Wild Cherry Creek, for example, 

 after being almost completely burnt over, was 

 subject to spring floods and to damage from 

 erosion. During July it would dry up at a dis- 

 tance of not over 2 miles from the mouth of the 

 canyon. As the watershed has become re- 

 forested these conditions have changed gradu- 

 ally until to-day the stream is not subject to 

 floods and erosion and is more regular in its 

 flow. During the summer it now reaches a 

 point 4 miles below the mouth of the canyon 

 and is used early in the fall for irrigation. 

 Apache Creek, which formerly flowed the full 

 length of its course all summer, since the de- 

 struction of the timber at its headwaters dis- 

 appears only 2 or 3 miles from its head; and its 

 only value for irrigation purposes after the 

 middle of June lies in its flood waters, which 

 are very uncertain. Hardscrabble and Medano 

 Creeks have suffered similar results, and the 

 list might be extended almost indefinitely. 



Forest Cover Restored. 



On the North Fork of the Gunnison River, in 

 western Colorado, much flood damage has oc- 

 curred as a result of the extensive fires which 

 burned over its upper watersheds in the late 

 seventies and early eighties. Previous to that 

 time the creek channels were narrow and rocky, 

 beavers were abundant, and the bottom lands 

 showed little erosion. In 1884 a heavy snow- 

 fall was followed by a flood which is estimated 

 to have ruined at least 2,000 acres of good 

 ranch land. Since then destructive floods have 

 occurred every few years. In 1912 irrigated 

 land and other property was damaged to the ex- 

 tent of some $20,000. a $5,000 bridge was 

 washed out, and $8,000 was expended in pre- 

 ventmg the destruction of two other bridges. In 

 spite of this comparatively recent damage it is 

 generally believed that floods are becoming less 

 frequent and less destructive as adequate fire 

 protection on the Gunnison Forest is gradually 

 restoring a forest cover on the burned-over 

 areas. 



