INTRODUCTION 3 



statements concerning ground water and what we should do 

 about it stems from this variety and from reference only to 

 records concerning selected parts of the country. Thus it is 

 true that in many areas water is pumped from wells faster than 

 it is replaced by nature. Such overdevelopment affects the 

 considerable part of our population dependent upon ground 

 water for agricultural, industrial, and municipal uses, but the 

 aggregate of these areas is less than 5 per cent of the country. 

 In a much larger proportion of the country the water levels 

 are not declining progressively, and in some areas ground- 

 water storage has increased appreciably in the past several 

 decades. 



It is true, also, that throughout most of the Nation there has 

 been little development of ground water. But those unde- 

 veloped regions include extensive areas where lakes and 

 streams furnish all the water required and there is little de- 

 mand for ground water. They also include extensive areas 

 where adequate supplies of good water cannot be obtained 

 from wells and large areas where very little is known about 

 the ground-water possibilities. The areas where large, unde- 

 veloped supplies of ground water are known to be available 

 occupy only a small fraction of the country's area. 



THE PROBLEMS 



The ground-water problems of one locality are rarely 

 unique, for other localities have encountered similar prob- 

 lems and in many instances have found satisfactory solutions. 

 These broad similarities in problems of various regions are 

 brought out in the grouping and classification followed in 

 subsequent chapters. Most of the serious problems of ground- 

 water "shortage" are in areas where significant quantities of 

 water are withdrawn from wells. Ground-water storage has 

 also been changed by other activities of man, sometimes to his 

 benefit, but more often to his disadvantage. Very commonly 

 these changes, incidental to the settlement of the country, have 

 been unintended and unforeseen. 



The difficulties created by pumping from wells are of sev- 



