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Norovirus Outbreak in Oysters Unrelated to West Point Overflow


Photo credit David Monniaux, mod. by Peter Gugerell

An outbreak of norovirus linked to consumption of raw oysters harvested in Puget Sound is not connected to temporarily reduced treatment capacity at King County’s West Point Treatment Plant.


The recent outbreak of norovirus resulting from consumption of raw oysters has received wide press because it results in outbreaks of gastrointestinal illness, and people started to wonder if it might be linked to the Feb. 9 West Point flooding incident.

It is unrelated. The norovirus outbreak began months earlier and spans waterways from Olympia to British Columbia. No stormwater-sewage bypasses have occurred at the plant since Feb. 16, and all beaches are open for recreation since Feb. 21.

Public Health-Seattle & King County published a helpful article on the recent outbreak, including helpful and detailed information about reducing risk from eating oysters.

The norovirus contamination of oysters appears to span the Salish Sea, and was first linked to illness in British Columbia in November. A second closure occurred in December, and yet another report was issued from Vancouver, B.C. in January.

The outbreak of norovirus-caused illness in King County is related to consumption of raw oysters. According to Hilary Karasz from Public Health-Seattle & King County, “The implicated oysters come from all over the Puget Sound – from down near Olympia to all the way up in Belllingham/Samish Bay. The outbreak started before the West Point flooding incident.”

Public Health has posted information about the norovirus outbreak and other foodborne illness outbreaks in our area.

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At West Point Treatment Plant, wastewater is being treated with hypochlorite — basically strong bleach– to kill bacteria and other pathogens in wastewater. The chlorine is removed before discharge 240 feet below the surface in Puget Sound through an offshore outfall that is 3,640 feet long.


As King County Wastewater Treatment Division (WTD) makes progress restoring West Point Treatment Plant, we are working to keep people informed and to answer questions and address concerns. WTD is carrying out additional marine and environmental monitoring, and we are posting plans, updates, and data online as they are available. We are providing updates in news releases and on the WTD blog.

We welcome people to contact us with questions and concerns as we restore West Point to full operations at or 206-477-5371.


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