FUTURE NEEDS FOR DEVELOPMENT 261 



designated areas, on the basis of the state's police power rather 

 than a declaration of public ownership of the water. 



In the areas where these critical problems have been solved, 

 it has generally been possible to reach the solution without 

 reducing the draft for beneficial use — by reducing waste from 

 wells, or prohibiting further increase in draft, or reclaiming 

 used water, or replenishing aquifers artificially, or tapping 

 new and undeveloped water resources. The best-known in- 

 stances of actual reduction in draft have been in areas where 

 water rights are based on the doctrine of correlative rights, 

 which provides for apportionment where water supplies are 

 not sufficient for all (see pages 60-61). 



The regulation of ground-water draft where rights are based 

 on appropriation is by no means so simple as the regulation 

 of surface-water diversions in order of priority. At each stage 

 of the stream there is water for just so many appropriators and 

 obviously none for those with junior rights. By reason of the 

 large storage in most ground-water reservoirs (perhaps accumu- 

 lated over a period of many centuries), there generally is water 

 for junior appropriators, even when the draft by senior ap- 

 propriators is exceeding the rate of replenishment. 



It is possible to utilize ground-water storage like a con- 

 structed reservoir on a stream, to give a large number of ap- 

 propriators fairly constant quantities from year to year, in 

 which case the junior appropriator's right is essentially equal 

 to that of his seniors', as long as the long-term total draft does 

 not exceed the average replenishment. For effective regula- 

 tion on this basis, it is essential to know the capacity for sus- 

 tained yield, commonly called the "safe yield." 



"safe yield." This term, originated by hydrologists, may 

 well prove awkward for them because of the variety of inter- 

 pretations possible. "Safe yield" is an Alice-in-Wonderland 

 term which means whatever its user chooses. Several defini- 

 tions have been proposed by hydrologists, some of which are 

 concerned only with hydrologic conditions while others are 

 tied also to economic conditions. But if written into statutes or 



