3-17 



Data from thermal infrared overflights, aerial photographs of 

 sewage effluent plumes, and drogue studies in the inner harbor confirm 

 the basic circulation pattern described by Duxbury. 



Salinity Distribution 



The physical/chemical water column measurement program for the 

 New Haven Harbor Station Ecological Studies has focused on ambient 

 salinity and temperature distributions. Review of the data from monthly 

 hydrographic surveys since May 1971, continuous measurements from the 

 Honeywell Water Quality Monitor (operating at the New Haven Harbor 

 Station pier since August 1970) , plant intake measurements by UI per- 

 sonnel, and special suirveys and supplemental data from other workers in 

 the harbor show that the degree of stratification varies sharply from 

 the head of the estuary (moderately stratified) to the mouth of the 



estuary (weakly stratified or well mixed) . 



') 



In general. New Haven Harbor's salinity fluctuations reflect 

 relative changes of rates of evaporation and precipitation (runoff) . As 

 a result of high evaporation and low freshwater runoff, maximum salinity 

 values are observed from June to September; lowest values occur during 

 February, March and April when freshwater runoff is at a peak. Warmer, 

 less saline water tends to flow out over cooler, more saline (and con- 

 sequently, denser) ocean water. Ebb-tide salinity values are lower than 

 flood-tide values at inner harbor stations during periods of significant 

 runoff. Mean salinity over the course of the sample year was 20.9 ppt 

 and ranged from 2.0 to 27.7 ppt. 



Data from the sample year (November 1976 through October 1977) 

 show the details of annual salinity variations in the Harbor (Figures 3- 

 5, 3-6) . During November sampling, Long Island Sound waters along the 

 axis of the main channel near the harbor mouth ranged from 27 ppt on the 

 surface to 28 ppt on the bottom. On the flooding tide, strong landward 

 flov/s created a sharp gradient between Stations 8 and 11 and carried 



(Text continued on page 3-26) 



