CHAPTER XII 

 DRAINAGE AND THE GROUND WATER SUPPLY 



ALARM is expressed from time to time over what is looked 

 upon as a diminishing ground water supply. Both open 

 ditching and tile draining are charged with removing 

 water which otherwise would wholly, or in part, sink into 

 the lower soil to retain the ground water at normal con- 

 dition. 



262. The ground water-table is falling. In many 

 parts of the United States, it is a matter of common knowl- 

 edge that for years springs have been drying up or dimin- 

 ishing in volume. Streams that once flowed in consider- 

 able volume have disappeared. In some cases they still 

 flow for a short distance over their old beds and finally 

 disappear below the surface. Wells that once furnished an 

 abundant supply of water at 10 to 30 feet below the 

 surface have failed in their supply, to be, in some cases, 

 supplanted by other wells of twice their depth. These 

 in turn have sometimes failed, and have given place to 

 drilled wells of much greater depth. The depth of water 

 of many of the deep-drilled wells is said to be decreasing. 

 From data gathered upon nearly 29,000 wells located in 

 forty-eight states, McGee l shows that in some regions 

 there is a considerable fall in the ground water level, and 

 that the fall is greater in dug than in drilled wells. From 



1 W J McGee, BuUetin 92, Bureau of Soils, "Wells and Sub- 

 soil Water." 



200 



