3-79 



Hydrographic surveys of New Haven Harbor were conducted by 

 Ebasco during May and September 1970 (Ebasco, 1971) . The surveys con- 

 sisted of releasing, at a known constant rate, a 30% solution of Rhoda- 

 mine B dye at the generating station discharge location and measuring 

 the resulting dye concentrations at the locations in the harbor shown in 

 Figure 3-23. Full-depth-averaged dye concentrations were obtained for 

 each survey location and related to temperature in the same manner as 

 was done for the NAI thermal surveys (NAI, 1976). Tables 3-4 and 3-5 

 show the temperature increase for the generating station, converted from 

 measured dye concentrations as an ebb slack, flood slack and tidal cycle 

 average. 



On a full-depth-average basis. Tables 3-4 and 3-5 show that 

 only one survey station, namely E20, will be subjected to temperature 

 increases of 1 F (0.5 C) or greater. A maximum full-depth-average 

 temperature increase of 1.22 F (0.7 C) was recorded at survey station 

 £20 at ebb slack during the EBASCO September survey. These temperature 

 estimates do not take into account thermal decay due to heat loss to the 

 atmosphere across the air-water interface. EBASCO also erected a non- 

 steady-state model for thermal plume (EBASCO, 1971) which was in general 

 agreement with the more accurate surveys and dye studies conducted post- 

 operationally (NAI, 1976; 1977). 



Continuous measurements of near-surface and near-bottom water 

 temperatures were made at the Honeywell Water Quality Monitor from 1974 

 through 1977. Table 3-6 gives the mean annual near-surface and near- 

 bottom temperatures for September to August, 1974-75, 1975-76, and 1976- 

 77. During the first year of plant operation (September 1975 to August 

 1976) , mean annual temperatures rose about 0.8 F over the preceding 

 year. From September 1976 to August 1977, mean temperatures dropped to 

 about 52.9 F, or about 1.6 F lower than in the preoperational year 

 shown, in response to the record cold of that year. It can be seen from 

 the Honeywell data that naturally occurring mean temperature fluctua- 

 tions are greater than those which may occur as a result of the thermal 

 load from the generating plant. Table 3-6 also shows that, on a yearly- 



(Text continued on page 3-84) 



