3-48 



and pH in the harbor. These changes were coincident with periods of 

 high or low freshwater flow from the river, which warms in the spring 

 and cools in the fall more quickly than the harbor waters, and which 

 governs salinity in most of the harbor. Quinnipiac River flow dilutes 

 harbor water progressively less as it mixes toward Long Island Sound; 

 its dilution effects were most evident in the river itself. 



Mill River 



Because of its low flow rate and extensive industrialization 

 (Fisher, 1974) , Mill River waters are the most deteriorated of those 

 entering New Haven Harbor. Low freshwater flow minimizes flushing, so 

 that water which has been contaminated from the East Street sewage 

 treatment plant and by industrial wastes is impounded in the Mill River 

 on successive tidal cycles. This impoundment causes further deteri- 

 oration of water quality by exposure to grossly polluted sediments (NAI, 

 1974c) and to heating by the English Generating Station. The highest 

 temperatures, most variable pH, and lowest dissolved oxygen and trans- 

 parency were found in the Mill River (Station 2) . 



Mill- Quinnipiac Confluence 



The harbor proper begins at the confluence of the Mill and 

 Quinnipiac Rivers, and the marine waters clearly dominate the hydro- 

 graphy and water quality of the area. Freshened waters from the Quin- 

 nipiac (which is tidal far above Station 1) commonly cause a "salt- 

 wedge" structure at Station 3; this is most prominent during periods of 

 high runoff. Salinity may differ by more than 10 ppt between surface 

 and bottom (7m, MLW) . The Mill River contributes turbid, heated water 

 with variable pH and low dissolved oxygen concentration to this site on 

 the ebbing tide. During flood tide. East Street sewage effluent flows 

 up to the site, and into the Mill River as well. High temperatures. 



