The reasonableness of a use is determined by the character of the stream, 

 the present conditions, and the location of users relative to each other. 

 Thus, it is a comparative sort of reasonableness and tends to be determined by 

 the courts on a case-by-case basis (Davis 1982). The courts have thus come to 

 play an instrumental role in protecting instream values, although it has been 

 a long and cumulative process. 



Four major court-created protection strategies have emerged. First, 

 there has been a trend towards recognition of private recreational uses as 

 "reasonable" under the riparian doctrine. Second, the courts have moved 

 towards protecting the waste assimilation capacities of streams under a variety 

 of State and Federal water quality control programs. Third, the courts have 

 been useful in protecting some element of natural flows on behalf of both mill 

 owners and metropolitan water supplies. Fourth, the courts have begun to 

 recognize the public interest right to protect streamflows on behalf of 

 recreation, aesthetics, and boating (Davis 1982). 



Eastern States have also been successful in initiating programs of their 

 own, especially in the last decade. In some States, for example, flow 

 standards have been set that limit the ability of riparian users to take water 

 in times of short supply. Streams and rivers have also been assigned, either 

 by State statute or administrative ruling, a "protected" status, as has been 

 the case under the appropriation doctrine in the West. A number of Eastern 

 States have begun to implement permit systems or to condition the operation of 

 existing and future dams so as not to affect minimum flow standards set for 

 instream values. Other States have incorporated priority systems, either in 

 State laws or within an administrative permit system. In this latter instance, 

 uses are categorized according to types of use (e.g., domestic, industrial, 

 water supply) and ranked in priority of use rights. In times of shortages, 

 the lower categories are required to reduce the amount of water being used, or 

 to stop use altogether. Increasingly, instream uses are being included in 

 these categorization schemes (Aiken 1983; Ehrlich 1983; Ertl 1985). 



In both the West and the East, then, opportunities do exist for protecting 

 instream flows; however, the degree of success encountered varies from State 

 to State and program to program. This is because, in practice, instream flow 

 protection efforts frequently involve controversy and lead to conflicts among 

 competing values and goals. The degree to which these conflicts are success- 

 fully resolved shapes the nature of the outcome. The key to successful 

 protection of instream uses is to negotiate permits and standards that give 

 adequate consideration to both viable economic interests in water resources 

 and instream values. This is a process that involves bargaining — and 

 compromise — among the interested parties to a conflict (Lamb 1980b). 



Instream flow resource problems have many nontechnical aspects that are 

 not sufficiently understood. Indeed, the political, legal, and institutional 

 facets of instream flow issues are often more complex than the technical ones. 

 It is in this regard that a dynamic, flexible tool for evaluating these 

 elements can be highly useful. An example may help illustrate this point. 



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