246 CONSERVATION OF GROUND WATER 



or prorata sharing, the landownership basis for water rights 

 is likely to be unsatisfactory when or where the water re- 

 sources are inadequate to meet the reasonable requirements 

 of all landowners. 



This is the situation in the arid regions where the water 

 supplies are so limited in comparison with the land suit- 

 able for irrigation or for other beneficial uses of water 

 that a prorata distribution to all landowners would lead to 

 disaster for everyone. No state in the arid regions, therefore, 

 subscribes exclusively to the common-law doctrines. In the 

 humid regions, too, there are small areas where the "reason- 

 able" needs of all landowners already exceed the available 

 water supply or can exceed it in the near future. All the humid 

 states, however, have surplus waters at some season of the year, 

 which flow from those states in streams. These surpluses can 

 serve to relieve local shortages and have been used for that 

 purpose in many places. 



WATER RIGHTS BASED ON PRIORITY OF USE. Most of the States 



of the arid regions have repudiated the common-law doctrines 

 in whole or in part by declaring water to be public property, 

 in which rights are acquired by appropriation; that is, the first 

 user of water acquires a priority to continue the use. It is ob- 

 vious that this is diametrically opposed to the common-law 

 doctrine, for the statutory doctrine of appropriation is based 

 on the time of use and on actual use without regard to the 

 ownership of the land where the water is appropriated. Never- 

 theless the "water law" in most of the 17 western states still 

 embraces both doctrines to some extent. Only Utah and 

 Nevada have declared appropriation to be the exclusive 

 method for establishing rights to all water; Colorado, Idaho, 

 and Oregon give preferential treatment to landowners in the 

 case of certain springs, seepage, and waste waters but other- 

 wise accept appropriation as the only means of establishing 

 water rights; and in New Mexico it may be inferred that 

 practically all ground water and surface water is subject to 

 appropriation. In the other states some waters are subject to 

 appropriation, and others are subject to rights gained by land 

 ownership. 



