Overview
Fig. 1 DOH Map of shellfish closure areas in the Salish Sea.
Coastal shellfish growing areas are threatened by poor water quality which can lead to a change in their classification and subsequent closures due to contamination from wastewater effluent plumes from land-based sources. Shellfish harvesting areas in the Salish Sea, often experience exposure to fecal bacteria which results in seasonal closures for harvesting due to the potential human health risk. Freshwater streams from the surrounding watersheds carrying agricultural runoff and wastewater effluent are hypothesized to be the major sources of fecal bacteria contamination impacting critical shellfish habitats in the Salish Sea including those in Whatcom and Skagit Counties. Although pollution prevention and source control actions have been implemented by regulators and stakeholders in these areas, the fecal bacteria pollution in the shellfish beds continues to persist requiring repeated closures of shellfish beds.
PNNL is supporting DOH efforts by conducting detailed analysis of the freshwater plume(s) circulation and transport in the study areas of interest using SSM. In addition to hydrodynamics and circulation, objective of SSM based analyses is to improve our understanding of persistent exposure of shellfish beds to fecal coliform (FC) bacteria. This would be accomplished with the implementation of a FC bacteria module for SSM.