Human development of the Salish Sea has resulted in loss and modification of salmonid habitats, including reduced habitat quality due to contaminant inputs, particularly in the lower reaches of rivers and estuaries of the central Puget Sound. Chemical contaminants released into the Salish Sea from anthropogenic sources can reduce the health and productivity of salmon. Juvenile salmon are exposed to contaminants in freshwater, estuarine, and marine habitats but they are particularly vulnernable as they transition from fresh to saltwater because this life history stage is especially sensitive to stressors that may reduce their early marine survival. Reduced growth and disease resistance have been demonstrated for juvenile Chinook salmon exposed to environmentally relevant contaminant levels; however, synoptic, Puget Sound-wide surveys to assess the extent and magnitude of contaminant exposure are lacking. In this study we measured exposure of juvenile Chinook salmon to chemicals of concern that enter Puget Sound via stormwater, wastewater treatment facilities, atmospheric deposition to marine waters, and groundwater. During the spring and summer of 2013, outmigrating fish were sampled from the river mouthes and two adjacent marine shorelines at each of five Puget Sound river-estuary systems: Skagit, Snohomish, Green/Duwamish, Puyallup/Hylebos, and Nisqually. We (1) report the extent and magnitude of exposure, (2) compare exposure in outmigrants across five major river-estuary systems, and (3) evaluate potential effects on marine survival. Results will be used to establish a time series of contaminant conditions in juvenile Chinook salmon to measure the effectiveness of current toxics reductions strategies and actions, inform future pollution reduction efforts, and enhanced recovery of Chinook salmon
