171 
Dredged material disposal causes an increase in turbidity of the receiving 
waters for 4a short period (2 to 5 hours). During previous dredzed material 
ocean-disposal operations, the highest surface concentration of suspended matter 
ebserved by Tetra Tech wes approximately 30 mg/liter (reported in Conner et alae 
1979). Chave- and Miller (1978) reported surface concentrations of over 60 
mg/liter 14 minutes after dredged material release. Long-term increased 
susoended solids resulting from disposal are not apparent in bottom waters. 
Analysis of near-bottom (less than 3m) suspended-solid concentrations, performed 
for this EIS, did not show any correlation between the levels of suspended solids 
and the presence of a dump site (Mud Dump or Sewage Sludge) or a natural 
geographic feature (Christiaensen Basin or Hudson Shelf Valley). 
—— 
High suspended sediment concentrations associated with dredged material 
disposal are unavoidable but short-term. Most organisms are not seriously 
affected by the suspended sediments in the water (Hirsch ec al., 1978). 
Generally, only concentrations of suspended sediments well above those created 
during most disposal operations cause mortality. Organisms normally associated 
with mud environments are highly tolerant of suspended sediments; Organisms not 
closely associated with muddy habitats are mote sensitive. Turbidity created by 
disposai is probably not a major environmental concern, but it could be an 
aesthetic problem if a dense plume approached beaches. The alternative sites are 
sufficiencly far from shore (Table 2-2) chat this effect could -not occur. 
NUTRIENT RELEASES 
Phytoplankton require nitrogen and phosphorus to photosynthesize and grow. 
Nutrient releases from dredged material disposal can stimulate biological 
activity and under certain conditions lead to rapid growth of wundersirable 
Organisms or toxic concentrations (Pequegnat et al., 1978b). The potential 
Occurrence of either effect depends upon environmental factors, such “as 
dissolved-oxygen levels and mixing and dilution rates. 
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