Streaming Media
Presentation Abstract
High levels of fecal bacteria have impacted key commercial and tribal shellfish harvesting at shellfish beds located in Samish Bay, Portage Bay, and Drayton Harbors in the Skagit and Whatcom County regions of the Salish Sea. Despite extensive pollution prevention and source control efforts since the 1990s, the problem of shellfish bed exposure to fecal bacteria persists. Based on site-specific experience, practitioners identified the need to better understand the marine circulation of pathogens near shellfish beds. Specifically, how currents driven by tides and winds move freshwater from rivers, streams, and outfalls is not well understood at these locations. The hypothesis is that major loading of the pathogens to critical shellfish habitats occurs through freshwater streams, causing direct exposure to fecal bacteria in the nearshore intertidal brackish environment. Improved understanding of circulation, mixing, and transport would provide the necessary insight to implement corrective actions. In this talk, we present preliminary results from the first two-quarters of a two-year project to conduct a detailed analysis of the freshwater plume(s) circulation and transport at these bays with shellfish beds. In addition to direct transport (hydrodynamics and circulation), the study seeks to improve our understanding of persistent levels of fecal bacteria. This would be accomplished by implementing a fecal bacteria module for the Salish Sea Model with application to Skagit and Whatcom County study areas, resulting in improved understanding of freshwater plumes dynamics and transport. Assessment of exposure of growing areas to freshwater plumes, considering their frequency and duration, is presented. The Salish Sea Model is a transboundary model; plumes from Georgia Strait will be included- especially for Drayton Harbor, which is located at the US/Canada border. Tribal, state, and local water quality programs are important partners on this work, and the results will benefit tribal, commercial, and recreational shellfish harvesters.
Session Title
Shellfish Galore
Conference Track
SSE9: Nearshore
Conference Name
Salish Sea Ecosystem Conference (2022 : Online)
Document Type
Event
SSEC Identifier
SSE-traditionals-107
Start Date
26-4-2022 1:30 PM
End Date
26-4-2022 3:00 PM
Rights
Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.
Type
Text
Language
English
Preliminary Assessment of Whatcom and Skagit Shellfish Bed Exposure to Fecal Bacteria using the Salish Sea Model
High levels of fecal bacteria have impacted key commercial and tribal shellfish harvesting at shellfish beds located in Samish Bay, Portage Bay, and Drayton Harbors in the Skagit and Whatcom County regions of the Salish Sea. Despite extensive pollution prevention and source control efforts since the 1990s, the problem of shellfish bed exposure to fecal bacteria persists. Based on site-specific experience, practitioners identified the need to better understand the marine circulation of pathogens near shellfish beds. Specifically, how currents driven by tides and winds move freshwater from rivers, streams, and outfalls is not well understood at these locations. The hypothesis is that major loading of the pathogens to critical shellfish habitats occurs through freshwater streams, causing direct exposure to fecal bacteria in the nearshore intertidal brackish environment. Improved understanding of circulation, mixing, and transport would provide the necessary insight to implement corrective actions. In this talk, we present preliminary results from the first two-quarters of a two-year project to conduct a detailed analysis of the freshwater plume(s) circulation and transport at these bays with shellfish beds. In addition to direct transport (hydrodynamics and circulation), the study seeks to improve our understanding of persistent levels of fecal bacteria. This would be accomplished by implementing a fecal bacteria module for the Salish Sea Model with application to Skagit and Whatcom County study areas, resulting in improved understanding of freshwater plumes dynamics and transport. Assessment of exposure of growing areas to freshwater plumes, considering their frequency and duration, is presented. The Salish Sea Model is a transboundary model; plumes from Georgia Strait will be included- especially for Drayton Harbor, which is located at the US/Canada border. Tribal, state, and local water quality programs are important partners on this work, and the results will benefit tribal, commercial, and recreational shellfish harvesters.
