697 
because they are determined by local activities and by stranded 
materials from widespread sources (MESA, 1977). 
Concentrations of artifacts (e.g., hair, fibrous material, 
etc.) derived from sewage sludge dumping will not increase and will 
probably decrease in the topographic lows north of the Christiaensen 
Basin. 
The cessation cf the dumping of sewage sludge at the 12-Mile 
site would reduce the navigational hazards produced by the barges 
during the dumping process. 
2.5b. Benefits to the Ecosystem 
With the cessation of sewage sludge dumping there should be 
measurable decreases in the concentrations of PCBs, bacterial 
pathogens and indicator organisms, and organic carbon in sediments 
and in associated biota. PCB loadings would decrease by 19-26% 
(O'Connor et al., in press d). The slight amelioration of measurable 
impacts will occur over a limited geographical area (approximately 
200-1 ,000 km?, probably). The benthic community in the small area 
immediately west of the sewage sludge site should become more 
normal, but the benthic degradation over wider areas (200-1,000 
km?) may not change noticeably. Instances of occurrence of extremely 
low dissolved oxygen concentrations in bottom water in the apex 
(particularly in topographic depressions) probably will become less 
frequent and perhaps less severe (Mearns et al., in press). 
2.6. The 65-Mile Site (120 km) 
The 65-Mile site (Figure 1) is located on the continental 
shelf and has never been used for ocean dumping. It was designated 
as an alternative site in 1978 by EPA on the basis of economic con- 
siderations (i.e. criterion--site to be located within 120 Km 
(65 n mi) of the harbor entrance) in the event public health problems 
associated with ocean dumping activites occur in the apex. The 
11-267 O—82——45 
