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5.0 CONCLUSIONS AND RECOMMENDATIONS 



The 1992 survey at WLIS was tasked with delineating the distribution and effects of 

 dredged material at the WLIS "F" mound, with evaluating the status of selected stations at the 

 WLIS "D" and "A" mounds, and with identifying new reference areas to replace WLIS-REF 

 and 2000S. 



Comparisons to the 1991 survey showed that a distinct mound, WLIS "F," was created at 

 the 1991-1992 disposal buoy location. The amount of material at this position was 

 consistent with the amount reported in disposal barge logs. The benthic community in the 

 immediate vicinity of the new mound appeared to be recovering at a relatively rapid rate. 

 It is expected to achieve a mature status within the following year, barring further 

 disturbance. 



Five stations of interest from the 1991 survey were intensively evaluated during the 

 present (1992) survey. In 1991 these stations exhibited unusually reduced sediment in 

 areas that had not experienced recent dredged material disposal. Under the DAMOS 

 Tiered Monitoring Plan, these stations were revisited in 1992 for both REMOTS® and 

 sediment toxicity testing. REMOTS® data showed mostly similar conditions in 1992, 

 although RPD depths were slightly increased. However, sediment toxicity testing with an 

 amphipod bioassay did not demonstrate any difference between these stations and control 

 and reference areas. Based on these results, it was concluded that no remedial action is 

 necessary at the WLIS "D" and "A" stations. The Tiered Monitoring Plan guidance 

 recommends these stations be re-evaluated within 12 months for any further changes in 

 community structure. 



One important source of disturbance in the western Sound area is periodic hypoxia in the 

 bottom water. This was not observed during the present survey, but it is not known 

 whether low oxygen conditions occurred prior to or following the survey. Hypoxia is a 

 transient phenomena, and its occurrence is related to a complex interaction of temperature, 

 stratification, organic loading, and tidal advection. As a result, CTD profiles taken on a 

 single day do not adequately describe any relationship between dredged material and water 

 column dissolved oxygen. However, the oxygen profiles observed during the survey were 

 typical of those seen in other areas of western Long Island Sound in the summer, and 

 these profiles did not show hypoxic conditions at the disposal site. Further, REMOTS® 

 results did not suggest any evidence of hypoxic events on the benthic community. 



The attempt to identify new reference areas to replace WLIS-REF and 2000S was 

 partially successful. Sediment chemistry and REMOTS® data showed that the new 

 reference area, SOUTH, was a good replacement for 2000S. However, the search for a 

 replacement for WLIS-REF was frustrated by the nearly ubiquitous presence of historic 

 dredged material to the north, east, and west of the present disposal site in REMOTS® 

 photographs. For the purpose of the present survey a reference area designated EAST was 



Monitoring Cruise at the Western Long Island Sound Disposal Site, July 1992 



