400 



PECK AND WARREN 



JAN. FEB. MAR. APR. MAY JUNE JULY AUG. SEPT. OCT. NOV. DEC. 



1973 



JAN. 

 1974 



Fig. 2 Intake and cut phytoplankton cell concentrations from 

 January 1973 to January 1974. 



measurable residual chlorine was detected at the cut for any of the 

 chlorine doses tested. At the lowest dosage (0.1 ppm), the 

 productivity dechned 65% at discharge and 84% at the cut. Thus a 

 chlorine dosage smaller by over an order of magnitude yielded 

 essentially the same effect as the highest dosage. 



Nitrate reductase activity declined only at the two highest 

 chlorine dosages. A 1.2-ppm chlorine application reduced nitrate 

 reductase activity 47% in the discharge effluent and 14% at the cut, 



