as possible of the water developed by the proposed construction 

 program would be diverted out of the Trinity River watershed; and 

 (3) the location of the structures is highly important. A dam at 

 the Lewiston site will cut off approximately 50 percent of the river 

 used by king salmon for spawning and a greater percentage of the 

 portion used by steelhead trout. A dam at the Browns Creek site 

 would deprive these fish of nearly 82 percent of their spawning 

 grounds . 



General Principles of Operation 



There are several general principles of operation which are 

 considered essential in any of the management methods suggested. 

 These principles have been established fron experience with other 

 projects and are incorporated herein to avoid many of the troubles 

 encountered elsewhere. 



1. The selected management procedure must be incorporated into 

 plans of the water development program before any construction work is 

 undertaken. 



2. All fish should be allowed to pass upriver until the summer 

 before the dams first act as barriers. By this time facilities for the 

 conduct of any maintenance program adopted should be installed and operable. 



3. Possible sources of stream pollution resulting froai construction 

 or its processes must be eliminated. 



4. Releases at the dams should be made from the lowest possible 

 level so that a minimum number of resident fish in the reservoirs will 

 be drawn through turbines or turned into diversions. Releases at low 

 levels in the dam will insure a supply of cold water to the stream 

 below. 



Maintenance Plans for Lewiston Dam 



Three methods of maintaining the salmon blocked by the Lewiston 

 Dam might be considered. First, additional spawning area might be 

 developed by increasing the river flow above normal during the 

 spawning period. Second, suitable tributary streams might be developed 

 into spawning areas. Third, fish hatcheries could be constructed. A 

 satisfactory management plan may be found in one or a combination of 

 these methods. 



Development of Additional Spawning Grounds in the Main Stream 



A plan for developing additional spavming areas by increasing the 

 river flow is believed to be the least expensive, easiest to operate 

 and least likely to prove unsatisfactory after it is placed into opera- 

 tion. The spawning bed surveys of 1945 showed conclusively that the 

 spawning capacity varied directly with the river flow. 



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