permitting a high degree of much-needed administrative discretion and flexi- 

 bility (White 1971). Ambiguity may even present opportunities, if correctly 

 handled; however, many individuals directly involved in the implementation of 

 different State instream flow programs are frequently frustrated by the 

 apparent lack of consistency. 



The States have developed their own mechanisms for distribution, which 

 tend to reflect the wide variation among the States in water law, supply, 

 demand, public attitudes, and historical precedent (Mann 1982b). In the West, 

 the "appropriation doctrine" was originally adopted, while in the Eastern 

 States the "riparian doctrine" has dominated. Although modifications of both 

 doctrines have appeared in practice, these two doctrines still form the basic 

 foundations of Eastern and Western water law as we see them today (Gould 1977; 

 Meyers and Tarlock 1980; Davis 1983). A brief review of these doctrines then, 

 is necessary to fully appreciate the current state of affairs in instream flow 

 protection. 



2.1. THE WEST: APPROPRIATION 



The first major use to which water was put in the West was in mining, 

 followed soon after by irrigation. Both require the removal of water from the 

 streambed, with the return flow often far less than the amount diverted. 

 Since water is scarce in the arid West, not enough was available to meet the 

 demands of all those desiring to use it. These basic facts gave rise to the 

 three fundamental principles of the appropriation doctrine: the priority 

 rule, the diversionary requirement, and the beneficial use requirement (Dewsnup 

 and Jensen 1977b; Tarlock 1978; Mann 1982b). 



The priority rule states that the first appropriator on a stream has the 

 prior right to use the water: "first in time, first in right" (Mann 1982b:24). 

 Thus, appropriati ve users are classified according to the dates on which each 

 began to use the water. In times of shortages, the most junior (i.e., latest 

 appropriation date) users may be required to cease operations, while the most 

 senior users continue to have the right to use the water. 



The diversionary requirement that water physically be removed from the 

 stream results from the fact that the first major and competitive water needs 

 were associated with diversionary activities. Diversions were also viewed as 

 a practical means for determining priority, since diversionary structures 

 served as physical evidence of the priority of the water right. The diversion- 

 ary requirement presented a major obstacle in early attempts to keep the water 

 instream (Dewsnup and Jensen 1977b; Tarlock 1978). 



Scarcity of water supplies also contributed to the development of the 

 third principle, that appropriated water be put to a "beneficial use." The 

 amount of water to which a user is entitled is no more than the amount that 

 can be put to a beneficial use. Failure to do so results in loss of the 

 appropriative right to the water by forfeiture or abandonment. "Beneficial" 

 uses, of course, were traditionally economic and developmental, as the mining 

 and irrigation customs became incorporated into common and statutory law 

 (Gould 1977; Tarlock 1978; Meyers and Tarlock 1980; Mann 1982b). 



