MOVEMENT OF THREE SPECIES OF FISHES 



537 



surface and spread laterally. During the summer, when flow was low, 

 a well-defined thermally stratified zone spread across the entire 

 width of the river and sometimes extended as much as 2 to 3 km 

 upriver and 3 to 6 km downriver. Cooler water flowed under the 

 thermal zone throughout the year, however, and composed about 50 

 to 60% of the cross-sectional area during the maximum thermal 

 development. This distribution changed when water was released 

 from the upstream reservoir; consequently, the thermal zone was 

 extremely variable even at its maximum development. 



The assimilation of waste heat from the generating facility is a 

 function of river water temperature, which varies with the season and 

 the flow rate of the river. A diurnal variation is expected as a result 

 of production demands, but this was complicated by the variation in 

 flow caused by discharge from Logan Martin Reservoir. A general 

 seasonal pattern was evident, however. During cool months water 

 temperatures were little affected except in the vicinity of the outfall. 

 As the season progressed, the temperature influence spread (Fig. 1) 

 until the maximum extent was evident in July to September, when 

 river water temperatures were highest and flow was lowest (Fig. 2). 



E. C. GASTO 

 STEAM PLAN 



Fig. 1 Surface temperature pattern, June 7, 1974. Temperatures 



o _ 



given in C 



