260 CONSERVATION OF GROUND WATER 



made that a vested right is taken away by the apportion- 

 ment, if the compact is otherwise upheld. 



In conflicts of smaller dimension, involving perhaps com- 

 munities within a single state or even a single county, the pres- 

 ent structure of water rights may be so intricate and complex 

 as to inhibit full utilization of the available water resources. 

 Here, too, a practical solution may be found by collective bar- 

 gaining that leads to agreements analogous to interstate com- 

 pacts. 



Compacts characteristically have been concerned primarily 

 with quantities of water. The quality of the water should also 

 be a significant element, especially for the downstream users, 

 since the upstream use contemplated in the compact must in- 

 evitably cause some deterioration in the quality. On the other 

 hand, if the deterioration is too great, the water will not be 

 suitable for its intended use downstream. 



Problems of interstate allocation of ground water have not 

 been important so far, but they are bound to arise in the fu- 

 ture as there is increasing development of ground water from 

 aquifers that cross state lines, particularly the ground water of 

 interstate watercourses. 



PROBLEMS OF REGULATING GROUND WATER 



The critical problems resulting from the increased utiliza- 

 tion of ground water in the past 20 years have given impetus 

 in many states to legislation for control of ground-water de- 

 velopment. Most of the western states now have statutes de- 

 claring ground water subject to appropriation, although some 

 statutes refer only to certain "classes" of ground water or to 

 certain areas within the state. The control of ground-water 

 development in most of these states is based upon scientific 

 investigations to determine the capabilities for natural replen- 

 ishment of individual ground-water reservoirs, and the total 

 appropriations are limited to that amount. Several eastern 

 states also have subjected ground water to regulation in certain 



