acceptable sediment concentrations (i.e., concentrations that are not 
expected to produce biological effects) within a reasonable time frame. 
Distribution of Chemicals in Puget Sound Sediments 
A general overview of the distribution of contaminated areas in Puget 
Sound is provided in Figure 5. With the exception of metals, 
hydrocarbons, and PCBs, few other contaminants have been measured in 
sediments from all regions of Puget Sound. Three general levels of 
contamination are shown in the figure: 1) areas where high contamination 
by one or more chemicals appears to be associated with biological effects, 
2) "clean" areas where contamination appears to be too low to cause 
effects (and in fact effects are minimal in the few areas tested), and 3) 
areas where the potential effects of intermediate levels of contamination 
are uncertain. As noted, this distribution gives only a rough guide to 
the potential environmental effects that may accompany the contamination. 
Mean and maximum concentrations of some common chemicals of concern 
are shown in Figure 6 for areas ranging from high to low contamination. 
Levels of contamination observed in different regions of the Sound 
correspond strongly with the level of development nearby. For example, 
the heavily industrialized areas of Seattle (e.g., the West Waterway of 
the Duwamish River) and Tacoma (e.g., Hylebos Waterway) are among the most 
contaminated and contain a complex mixture of toxic substances. The 
Ruston-Pt. Defiance Shoreline near Tacoma contains high levels of certain 
metals associated with a smelting operation on the shoreline. 
Other contaminated areas, such as Eagle Harbor west of Seattle at 
Winslow, are grossly contaminated in small areas with only a limited 
number of related substances (i.e., hydrocarbons likely derived from 
creosote). The harbors at Everett and Bremerton receive wastes from major 
pulp and paper mill and naval ship repair operations, respectively. These 
harbors are areas of high contamination, and will be more completely 
characterized in studies to be completed by PSEP in 1987 and 1988. Some 
areas of concern in the past are now less contaminated. For example, high 
mercury contamination observed in Bellingham Bay during the late 1960s has 
lessened after the source was shut down and contaminated sediments were 
buried by cleaner material. 
The pattern of contamination in Puget Sound demonstrates that, with 
the exception of spills and intentional dumping at dredged-material 
disposal sites, distance from source discharges is the major factor in 
determining the levels of contaminants in Puget Sound sediments. Areas 
that have intermediate levels of contamination (e.g.. Central Puget Sound 
between Seattle and Tacoma; Figure 6) are predominantly influenced by 
water currents that transport contaminants from areas with major sources. 
Areas with low contaminant levels (e.g., bays used as reference areas; 
Figure 6) are generally far from major development. Even in these areas, 
natural transport by air and water has introduced contaminants. Probably 
no area of the Sound is free from some contamination by toxic chemicals. 
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