20% to 50% of precipitation is thus saved for underground seepage. 



As the country is built up and deforestation increases, the run-off 

 also increases, for it is no longer held by the forest cover, but flows 

 off along the surface ; and in the case of snow it melts much more 

 rapidly and flows off on the frozen surface of the ground and is lost. 



For power plants and factories along the lower stretches of the 

 streams, the regularity and uniformity of the supply are quite as 

 important as the volume ; and it is for the regulation of stream- 

 flow that forests are of pre-eminent importance; to hold the pre- 

 cipitation, no matter at what time of year or in what form it falls, 

 and to distribute it uniformly throughout the year. 



These same streams may also be the source of supply of water 

 for farms, towns and cities along their course, and here forest cover 

 also aids in preventing silting and pollution of the water. Only 

 about 1% of the available supply is used for this purpose; about 2% 

 for irrigation ; 5% for navigation, and less than 5% for power ; but 

 the forest cover has an important influence on the control of freshet 

 and flood waters, as well as in the prevention of erosion. Floods 

 from unusual conditions, such as cloudbursts, are of course, not 

 prevented by forest cover. 



It is the water that soaks into the ground upon which a sustained 

 water supply depends. Run-oft" water is worse than wasted, for it 

 might have saved some non-restorable resource, such as coal ! Recent 

 reports of hydraulic engineers of prominence (Chicago, Minneapolis 

 & St. Paul Railroad) afifirm that one horsepower steam costs $150 

 per annum, while the same energy derived from electricity costs 

 about $40. Steam is wasteful, for fires must be kept up while en- 

 gines are blowing off steam on a siding, while with electricity, the 

 power may be cut off when not in use. (It is further stated that 

 while a locomotive runs 150 miles and then goes to the round-house 

 for repairs, an electrical engine runs 1200 miles before being re- 

 turned for repairs.) 



Now, forest cover prevents too rapid run-off and so conserves the 

 supply of water. The force of the drops of rain is broken, and 

 beating and compacting of the soil is prevented, also the too rapid 

 melting of snow is checked effectively. In our western country, 

 spring floods are often followed in two months by severe droughts ; 

 and all over the country the results of deforestation are now plainly 

 felt, particularly in our largest drainage basins, as the Mississippi 

 and the Ohio. 75% of the water is lost on non-forested water sheds, 

 nor does this represent but a part of the waste, for the damage done 

 by these floods must also be considered. These floods are new 

 in this country. Many can not understand them, since we have not 

 any greater precipitation than formerly ; but they are no novelty in 

 Asia and in Europe ; and millions have already been spent there to 

 prevent their occurrence. 



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