large material or inflow volume that has low concentrations. 
Computation of total toxicant inputs represents only the first step in 
understanding the overall significance and effect of pollution in Puget 
Sound. 
Three recently completed studies supported by EPA, the Municipality of 
Metropolitan Seattle (Metro), and NOAA in Puget Sound provide "first 
cut" estimates of mass loading for selected contaminants. These 
studies include Water Quality Management Program for Puget Sound (Jones 
and Stokes, 1983); Metals/Toxicants Pretreatment Planning Study 
(Romberg et al., 1984); and Toxic Chemicals and Biological Effects in 
Puget Sound (Quinlan et al., 1985). 
In the Jones and Stokes, 1983 report only pollutant loadings associated 
with municipal and industrial discharges were considered. The 
information reported was primarily for conventional pollutants; organic 
pollutant data was sparce. Due to these limitations, total pollutant 
loading and the relative importance of each source was not assessed in 
this report. In the TPPS report (Romberg et al., 1984), the main basin 
of Puget Sound was the primary focus of the contaminant loading 
estimates. Loading data was presented for both metals and synthetic 
organic components. 
Quinlan et al. 1985 developed contaminant loading estimates for five 
source categories and three major classes of chemical contaminants, 
including metals, polynuclear aromatic hydrocarbons (PAHs) and 
polychlorinated biphenyls (PCBs). Sources included: rivers, shoreline 
erosion, atmospheric deposition, municipal sewage effluents and 
industrial waste effluents. This report presents the most complete 
picture of contaminant inputs to Puget Sound available to date and is 
the basis of loading values that will be presented here. However, 
calculated loadings are considered only as preliminary estimates due to 
the lack of detailed concentration data available to perform the 
computations. Substantial information gaps exist for concentrations of 
metals and organic constituents in all sources discharging to Puget 
Sound. 
Although the historical data base is limited, the estimated loading for 
a number of chemical contaminants which occur in high abundance in 
Puget Sound has been quantified as a first approximation. This report 
briefly summarizes the existing information and provides an overview of 
the type of sources contributing to the contamination of the Sound, the 
quantities of contaminants emitted by these sources, and the main 
subregions of Puget Sound receiving these inputs. The main subregions 
of Puget Sound for which contaminant loadings have been calculated are 
14 
