Fiinc 



therefore, overall availability. Since the topic of water 

 quality is discussed in the next section, this discussion 

 will focus only on the question of overall water supply. 



There is no overall shortage of water in the United 

 States. The total amount withdrawn from surface- and 

 ground-water sources for public water supply systems in 

 1975 (the last year for which accurate figures are avail- 

 able) was about 27 billion gallons a day, or about 6 percent 

 of the average annual flow of the Mississippi River at New 

 Orleans, in addition, less than one fourth of the with- 

 drawn water was consumed and unavailable for reuse after 

 treatment (NRC-7). However, there are dramatic in- 

 stances of regional and local scarcities from time to time. 

 and the consequences of those shortages have made effec- 

 tive utilization, conservation, and distribution of water an 

 important national priority and a factor in our interna- 

 tional relations (NRC-7; ASTR~11I). The U.S. Water Re- 

 sources Council has reported that seasonal shortages are 

 common in 20 percent of the 106 watershed regions of the 

 country, and that number is projected to reach 40 percent 

 by the year 2000.' In certain western regions of the United 

 States, seasonal shortages are the rule rather than the 

 exception, and those water shortages are exacerbated by 

 current major population shifts, with consequent in- 

 creases in water demand for personal use and, especially, 

 for energy production (NRC-7). Moreover, the Western 

 Research Committee recently reported to the Joint Coun- 

 cil on Food and Agriculture a projected need for 20 

 percent more water over the next 20 years in the western 

 region.^ 



Ensuring adequate water supplies is primarily a non- 

 scientific or nontechnical issue. Problems associated with 

 water availability generally are a result of competition 

 within geographical areas between water needs for agri- 

 cultural purposes and those for energy producton, or 

 between those kinds of needs and those for other industrial 

 purposes; the allocation and reallocation of water among 

 the competing needs are primarily nontechnical policy 

 decisions. But science and technology activities may be 

 able to lessen the problems in the coming years by provid- 

 ing technological options for redistributing water, increas- 

 ing the available supply, or increasing the efficiency of 

 water use. 



REDISTRIBUTION OF WATER 



Of the options available for resolving water scarcity prob- 

 lems, redistributing water is clearly the most difficult 

 politically. However, assuming that institutional or politi- 

 cal barriers to interbasin transfers could be overcome, 

 scientific and technological advances could be useful in 

 providing more effective mechanisms for redistributing 

 water from areas of high supply to those of low supply. 

 Many attempts have already been made at finding the best 

 means for redistributing water, including piping and re- 

 directing streams and river flow patterns. But, again. 



tioiuil Area Problems, Opportunities, and Constraints 63 



those solutions have major political, ecological, and en- 

 vironmental ramifications. Redistributing water can re- 

 duce both the quality and the quantity of water resources 

 elsewhere. Therefore, until new and more acceptable 

 techniques are developed or the tried techniques are sub- 

 stantially improved, and until policy decisions are made 

 that remove the institutional barriers to redistribution, 

 water redistribution will prove almost certainly to be an 

 ineffective mechanism for ensuring adequate supplies of 

 water in all regions. 



INCREASING THE AVAILABLE SUPPLY 



There is some potential for increasing the available supply 

 of usable water through scientific and technological de- 

 velopment. For example, there always is the possibility of 

 identifying and exploiting additional ground-water sup- 

 plies, and the U.S. Geological Survey has initiated a 

 major program directed to that goal. Another approach 

 would be to increase efforts at converting seawater or 

 brackish water to useful quality (NR; ENVIRON; 

 ASTR-III). 



It also is possible to increase the amount of water 

 available in water-scarce regions by artificial means. 

 Cloud seeding and other forms of climate change may be 

 able to increase regional water supplies by as much as 10 

 percent (ASTR-III). However, any attempts at altering 

 climatic conditions would have to be undertaken with full 

 consideration of the complex ecological , social , and polit- 

 ical ramifications. 



INCREASING THE EFFICIENCY OF WATER USE 



The problems of regional water shortages in the coming 

 years can be lessened by technologies for increasing the 

 efficiency of water use. for aiding conservation, and for 

 increasing the potential for water reuse. Technological 

 advances that increase both industrial and domestic water- 

 use efficiency already have aided conservation efforts. 

 Some progress has also been made in controlling water 

 loss from agriculture and from urban runoff In addition, 

 some water recycling and desalination programs have 

 been initiated and, although currently expensive, show 

 some promise for functionally increasing the amount of 

 water available for a variety of uses. At the forefront of the 

 research effort, the Department of Agriculture is sponsor- 

 ing research directed at developing less water intensive 

 crops, and the National Science Foundation supports in- 

 vestigations into crops that can grow in water of high 

 salinity ( AGR; Outlook 1: ASTR-III). However, to exploit 

 fully the potential for water conservation and reuse, addi- 

 tional efforts of those kinds, coupled with policy deci- 

 sions fostering the efforts, will be needed during the next 

 5 years. 



