WATER, AND ITS USES 105 



fertile loam soils of the central portions of the country, 

 products of the decay of vegetation through long periods of 

 time were washed away from the surface slopes. 



As direct result of ill-advised methods of cultivation of these 

 slopes, not only were they denuded of their best soil but they 

 became gullied and worthless as tillable land. Proper con- 

 servation through tillage and general management might 

 have kept these lands productive for all time. Rivers like 

 the Missouri and the Mississippi have their waters laden with 

 soil washed from the land surfaces within their basins, and 

 this earth material is almost wholly lost as available 

 productive soil 1 . A similar process continued through longer 

 periods has resulted in some parts of the world, such as 

 northern China, in large areas unfit for tillage and for all 

 agricultural pursuits. Though large areas of productive lands 

 are being brought into use by irrigation in the arid sections of 

 the country, the annual losses by erosion of tillable lands, and 

 the washing away of their most fertile parts, represents a 

 deplorable waste of the wealth of the nation. So dependent is 

 the present prosperity and the future greatness of any people 

 or nation upon the productiveness of the soil that its impover- 

 ishment rather than its betterment is a national calamity. In 

 1902 the Reclamation Act was passed by Congress authorizing 

 large outlays for irrigation systems in the arid regions of the 

 United States. These undertakings have involved the build- 

 ing of great dams for storage of waters and the construction 

 of water channels. In Colorado, water from the Gunnison 

 River is made to flow through a long tunnel to irrigate the ad- 

 joining valley. The sale of "water rights" on irrigated lands 

 is expected in time to return to the government all the 

 outlays made. 



1 It has been estimated (Salisbury) that the amount of sediment carried 

 daily into the Gulf of Mexico by the Mississippi River is equal to dumping 

 mud and sand into the waters of the gulf at the rate of over thirty car loads 

 of twenty-five tons each every minute continuously day and night. 



