3-90 



ranging from 7.4% to 40.2%. August showed less variability; the range 

 then was from 22.3% to 41.6% of the area of Transect F. 



During 1976, NAI analyzed aerial infrared imagery and "ground 

 truth" information to assess the extent of the generating station ther- 

 mal plume and the magnitude of other thermal inputs to New Haven Harbor 

 (NAI, 1976) . These data covered the period of September 3 and 4. With 

 the plant at or near full load, it was found that the 2 F AT isotherm 

 encompassed approximately 2.3 to 5.5% of the inner harbor surface area 

 at high slack and maximum ebb flow, respectively. The maximum surface 

 temperature in the vicinity of the discharge was 74 F during low slack 

 tide. This represented an increase of 4 F over adjacent surface water 

 temperatures . 



Increased surface water temperatures were observed in other 

 areas of the harbor. Maximum surface temperatures from the UI English 

 Station of 72 to 76 F (22.2-24.4 C) were observed in the Mill River. In 

 the shoal areas along the western side of the harbor, solar radiation 

 raised the temperature of the water above 74 F (23.3 C) . 



Thermal addition was not sufficient to cause fog or to signifi- 

 cantly affect winter ice cover. 



In summary, the thermal discharge from New Haven Harbor Gen- 

 erating Station: 



1. raises full-depth tidal cycle average temperatures 

 by less than 0.8 F in the inner part of the harbor 

 and less than 0.5 F in outlying areas. 



2. raises surface temperatures by a maximum of 4 F where the 

 plume intersects the surface. 



3. can occasionally cover the complete cross-sectional area 

 of the navigation channel with water 1 to 2 F warmer than 

 ambient. 



