10 CONSERVATION OF GROUND WATER 



of the total precipitation. It is because of this water cost that 

 treatment of some watersheds can reduce overland flow, in- 

 crease infiltration and soil moisture, and yet not cause any per- 

 ceptible increase in storage in an underlying ground-water 

 reservoir. 



OUR INCREASING REQUIREMENTS FOR WATER 



Available information indicates that the total water used for 

 irrigation, industrial, and public supplies throughout the Na- 

 tion may be as great as 200 billion gallons a day, of which prob- 

 ably less than 40 per cent is actually consumed and returned 

 to the atmosphere. Thus the national use is nearly 200 times 

 that of New York City's 8 million inhabitants. Probably less 

 than 15 per cent of this total is derived from ground-water 

 sources. It has been predicted that the current usage may be 

 doubled within a few decades, judging by the trend in recent 

 years and the indications of large additional demands for new 

 purposes. It is likely that ground water will be called upon 

 to continue to furnish the same, if not an increased propor- 

 tion of the total demand, because of recognized advantages in 

 uniformity of quality and quantity. 



What will be the result of any effort to increase our ground- 

 water development so tremendously? Certainly, if we con- 

 tinue the pattern of development of the past few decades, the 

 likelihood is that current ground-water shortages in many 

 areas will be intensified and many new "critical'' areas will 

 be created. This would be an appalling predicament and a 

 sad commentary on the Nation's astuteness, in view of the 

 known possibilities for far more effective utilization of the 

 available supplies. 



THE NEED TO KNOW WHAT WE ARE DOING 



The imperative need in ground-water development, past 

 and future, is to know what we are doing. That knowledge 

 comes from probing into the methods by which nature puts 

 water into the ground and takes it out again, as well as the 

 changes that man makes or can make by his activities. 



