238 CONSERVATION OF GROUND WATER 



The skipper of the Queen Mary regards all the inland waters 

 of the United States as unusable, and yet he can use water of 

 any kind, provided only that it is 70 feet deep. Saline ground 

 water in Baltimore is more usable for cooling in industrial 

 plants than the potable public water supply, and it is possible 

 that the return of water to a ground-water reservoir after it 

 has been used (and warmed) for air conditioning might be 

 more detrimental to further use than if the reservoir were 

 replenished instead by cool sea water. The sewage effluent of 

 the Los Angeles area, after complete treatment and percola- 

 tion into ground-water reservoirs, may well be of better 

 quality for domestic or industrial use than the imported Colo- 

 rado River water. Along the Pecos River in Texas, both sur- 

 face and ground waters are used for irrigation, although some 

 have almost half as much mineral matter in solution as sea 

 water, and nearly all would be classed as "unsatisfactory or in- 

 jurious" for irrigation in other regions. The secret of success 

 along the Pecos is the selection of permeable soils and of crops 

 tolerant to such mineralized waters and the application of a 

 sufficient excess of water to carry off salt residues in the soil. 

 After long-continued use of such inferior water, soils may 

 develop characteristics that make water of better quality "un- 

 usable" on them. 



An inventory of water utilization should differentiate the 

 use into categories of consumptive use which returns water 

 to the atmosphere, consumptive waste which also returns 

 water to the atmosphere but without benefit to man, and non- 

 consumptive use, after which the water is returned to surface 

 or ground-water bodies. The quantity used consumptively is 

 a straight deduction from the total water available for use, and 

 the consumptive waste is similar except that it may be possible 

 and desirable to divert some of that water to beneficial pur- 

 pose. 



The water used nonconsumptively may be entirely suit- 

 able for further use, but on the other hand it may be so 

 contaminated as to be unfit for further use and if discharged 

 into a stream or ground-water reservoir might even render a 



