EFFECTS OF POWER-PLAIMT OPERATION 



603 



TABLE 1 



TOTAL PHYTOPLANKTON MEANS 

 IN BELEWS LAKE, 1972-1976 



Power-Plant Influence on Total Standing Crop 



There were 19 sampling periods when thermal effluent was being 

 discharged into the lake, four months when the plant was shut down, 

 and 21 months in the preoperational period when the lake was free 

 from thermal effects. Samples taken at the four stations in the 

 circulation pattern (3, intake; 1904, discharge; 1907; and 1906) 

 during periods of thermal discharge and during periods when there 

 was no thermal effect were compared to determine how often there 

 were significant differences in total phytoplankton density at 

 adjacent stations. A fifth station (1118, near the dam and least 

 affected by the circulation pattern) was included as a control. 

 Differences were considered significant if there was no overlap in the 

 95% confidence limits for the density counts at adjacent stations 



