^)fKaU<iA 



STUDY SECTION DELINEATION 



Study sections were selected on the basis of the location of diversion 

 structures, access, fishing pressure, future and existing dam sites, and 

 the various habitats present. The Tongue River downstream from Tongue River 

 Dam was divided into five zones, identified by Roman numerals (figure 2). 

 Primary sampling sections (lb, lib. Ilia, IVb, Vc) were established in 

 relation to irrigation diversion structures to evaluate fish distribution 

 (table 1). Another primary section, Vb, was established to obtain data for 

 a reach of river which would be inundated by the New Tongue River Reservoir. 

 These sampling sections were relatively short (2.5-4.1 km) and did not 

 adjoin one another. In all, sampling sites were established on 11 sections 

 of the river (see figure 2). Primary sections ranged in length from 2.5 to 

 4.1 km; gradients varied from 0.56 m/km (2.94 ft/mi) near the mouth to 1.22 

 m/km (6.45 ft/mi) in the canyon. 



TABLE 1. Description of major sampling sections. Tongue River. 



^ River kilometers above the mouth 



Major habitat zones and sampling sites were delineated through the use 

 of aerial photos, USGS topographic maps, and ground measurements. 



INSTREAM FLOW DETERMINATION 



Instream flow levels were obtained through the use of the water surface 

 profile (WSP) program (USDI 1968) following procedures outlined by Dooley 

 (1975) and Spence (1975). 



The validity of WSP and its potential use in determining instream flows 

 for a warm-water stream were investigated. Flows for migration, spawning, 

 and rearing were evaluated (Elser 1976). Predicted values for water surface 



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