ABSTRACT 



An eighteen month biological study showed the heated brine effluent 

 from a desalination plant in Key West, Florida caused a marked re- 

 duction in biotic diversity. Some organisms were more abundant in 

 the receiving waters than in control areas but these were generally 

 capable of isolating themselves from the effluent by closing up 

 or by moving to other areas during periods of high contamination, 

 Ionic copper, discharged from the plant, was the most toxic feature 

 of the effluent. Temperature and salinity of the effluent and the 

 receiving water were such that the effluent stratified at the bottom 

 of the receiving basin. This stratification reduced water circula- 

 tion and the man-made harbor acted as a settling basin which lessened 

 the impact of the discharge on surrounding natural environments. 



Periodically, the plant shut down for maintenance or cleaning. When 

 it resumed operations, low temperature water of ambient salinity was 

 discharged which was highly contaminated v;ith ionic copper. These 

 sudden effusions caused more biological damage than steady-state con- 

 ditions. At the end of the study, extensive engineering changes were 

 made to correct corrosion problems and lower copper discharge. 



This report was submitted in fulfillment of Contract No. 14.12,888 

 under the sponsorship of the Environmental Protection Agency. 



Ill 



