1.0 INTRODUCTION 



During the period October 2, 1993 through January 31, 1994, the U.S. Army Corps 

 of Engineers, New England Division (NED), conducted maintenance dredging of the 

 navigational channel in New Haven Harbor, Connecticut (Figure 1-1). This operation 

 removed approximately 840,{XX) cubic yards of sediments which were then disposed at the 

 Central Long Island Sound Disposal Site (CLIS). Prior to the initiation of this project, the 

 State of Connecticut Department of Environmental Protection (DEP) expressed concerns 

 regarding the potential dispersion of sediments resuspended by dredging and the deposition of 

 these materials in areas defined as being "environmentally sensitive" because of their 

 frequent use by flounder as a spawning area. These spawning grounds are located to the west 

 of the federal navigational channel and to the north of the inner breakwater adjoining Sandy 

 Point (Figure 1-1). Additional flounder spawning areas may be found at the southeastern 

 limit of the harbor, within Morris Cove. In response to DEP concerns, the NED initiated a 

 field investigation designed to monitor dredge-induced resuspension and to detail the area 

 affected by the dispersion of these materials. This report provides a summary and discussion 

 of the observations obtained as part of this investigation. 



The major objectives for the field investigation of dredge-induced resuspension and 

 the associated dispersion were defined as follows: 



• To determine the normal background levels of suspended materials 

 in New Haven Harbor immediately prior to and during the dredging 

 of the federal navigational channel in the fall of 1993. 



• To monitor the plume of materials suspended by dredging 

 operations during flood and ebb tidal conditions to determine a) the 

 spatial extent of the plume and b) its trajectory relative to the areas 

 identified by the State of Connecticut Department of Environmental 

 Protection as winter flounder spawning areas. 



The study area lies within New Haven Harbor, Connecticut's largest port facility. 

 Most of the tonnage entering the harbor is in the form of petroleum products, transported via 

 tankers which use the 10,5 meter dredged navigation channel. Three tributaries feed into 

 New Haven Harbor, the West River, the Mill River, and the Quinnipiac River, Both the 

 West and Mill Rivers are small; the West River is only 3 km long and the Mill River's 

 source, Whitney Lake, is less than 10 km ft-om the harbor. The input from these two rivers 

 can be considered negligible. Freshwater contributions from the Quinnipiac are also minor 

 relative to the total flux of water in and out of the harbor (Richards 1988). The annual mean 

 flow from the Quinnipiac gaging station in Wallingford, CT, for the period of record 1931 to 



Dredged Sediment Dispersion in New Haven Harbor 



