FUTURE NEEDS FOR DEVELOPMENT 253 



subordinate their rights to others in periods of deficient sup- 

 ply, when the need for water is greatest. 



The constitutions and statutes of many states grant various 

 preferences in the use of water, which may take precedence 

 over the priorities of established rights. Generally water for 

 domestic and municipal use is accorded the highest prefer- 

 ence, with use for irrigation, industry, mining, and power fol- 

 lowing in that order. Texas gives preference to industrial use 

 over irrigation and adds use for navigation and for recreation 

 at the bottom of the list. This preferential treatment operates 

 in various ways in various states: it may be the basis for choos- 

 ing between pending applications to appropriate water or for 

 denying an application if it is deemed not to serve the public 

 interest; it may permit municipalities to reserve water for 

 their future expanded requirements or may permit condemna- 

 tion of an existing use in favor of use with higher preference, 

 with compensation; and in times of water deficiency the availa- 

 ble water supplies may be restricted among the established 

 rights on the basis of preferential use rather than priority of 

 use. 



Navigation is the superior use of the water of a navigable 

 stream, based on the constitutional power of Congress to regu- 

 late interstate commerce. South Dakota has taken cognizance 

 of this in a statute exempting its navigable waters from ap- 

 propriation, but the importance of navigation to the arid states 

 is perhaps better epitomized by the Texas statute which places 

 navigation above "recreation and pleasure" but below all other 

 uses of water in a list of preferences. 



Congress in recent legislation has also accorded navigation 

 a low priority in arid regions. Sections 1(b) of the Flood Con- 

 trol Act, approved December 22, 1944, and of the River and 

 Harbor Act, approved March 2, 1945, provide that: 



The use for navigation, in connection with the operation and 

 maintenance of such works herein authorized for construction, 

 of waters arising in states lying wholly or partly west of the 98th 

 meridian shall be only such use as does not conflict with any bene- 

 ficial consumptive use, present or future, in states lying wholly 



