Sewage spill in Seattle triggers warnings in Kitsap County

It was a tale of two health advisories that created a bit of confusion in Kitsap County following a major sewage spill last week from King County’s West Point treatment plant.

A beach closure in Kitsap County included the eastern shoreline of Bainbridge Island north of Eagle Harbor plus North Kitsap from the Agate Pass bridge to Point Jefferson between Kingston and Indianola.

Brown color designates areas closed to shellfish harvest because of pollution. Click to see state map for details on closures.
Map: Washington State Department of Health

The closure area was determined in part by computer models, which showed that spills of sewage, oil and other substances are capable of crossing Puget Sound from Seattle and hitting the shore of Kitsap County, according to Scott Berbells, section manager for shellfish growing areas, a division of the Washington State Department of Health.

Such a scenario occurred in December 2003, when 4,800 gallons of heavy fuel oil spilled from a barge at the Chevron/Texaco Facility at Point Wells, south of Edmonds. The oil crossed Puget Sound and damaged shellfish beaches in North Kitsap. See Kitsap Sun, Dec. 31, 2003.

The latest spill, about 3 million gallons of raw sewage mixed with stormwater, occurred at West Point in Seattle’s Magnolia area — about 20 miles south of Point Wells.

The exact trajectory of a spill depends greatly on winds and tidal currents, but state and county health officials tend to be cautious, thus the closure of Kitsap County’s shoreline. Water-quality testing has not revealed the presence of bacteria from the West Point sewer spill, but the tests are limited to a few areas, according to John Kiess, environmental health director for the Kitsap Public Health District. It is best to be cautious in these situations, he said.

The two health advisories that led to some confusion are a no-contact advisory, which advises people to stay out of the water, and a shellfish-closure advisory, which strongly suggests that nobody take shellfish from affected beaches. Commercial shellfish growers must comply with mandated closures.

The no-contact advisory was in place from July 19 to July 22, when it was lifted. John Kiess told me that the public should have been notified of a 21-day shellfish closure, which will remain in effect until Aug. 9. The notice of the shellfish closure went out today.

Any confusion among health officials was because the 21-day shellfish closure is a fairly new way of addressing closures for recreational shellfish harvesting, John said, noting that the county works with the state for consistent policies.

The 21-day closure was actually designed for commercial shellfish growers, according to Scott Berbells. It was adopted from federal Food and Drug Administration rules imposed within the last couple years, he said. The state policy — followed by Kitsap County — has been to announce recreational shellfish closures consistent with commercial closures.

Scott explained that shellfish closures last a lot longer than no-contact advisories. If shellfish pick up the pollution in their tissues, it generally takes a lot longer for the shellfish to become clean again, whereas contaminants in the water will become diluted in a short time, making it safe to swim in a few days.

As for the models that predict pollution plumes, several are available, including at least one in King County being used to determine where shellfish beds can be safely opened to commercial harvest.

Click on the map to go to an animated simulation of the plume created by an oil spill in Seattle.
Graphic: University of Washington Coastal Modeling Group

One model, which recently became available for public use, provides a three-day forecast of water temperature and chemistry, based on tides, water circulation and other factors. Developed by the University of Washington Coastal Modeling Group, the model is called LiveOcean. You can view a simulation of an oil spill on a page titled “Forecast of surface salinity and simulated oil spills.” Click on the start button and notice how an oil spill in Seattle creates a plume that can reach Bainbridge Island and even points north.

“LiveOcean works a lot like the weather forecast models that we all rely on every day,” states the opening to a description of how the model works. “It takes in information about the state of the ocean, atmosphere and rivers on a given day, and then uses the laws of physics (and a large computer) to predict how the state of the ocean in our region will change over the next few days.

“The things that the model predicts are currents, salinity, temperature, chemical concentrations of nitrate, oxygen, carbon, and biological fields like phytoplankton, zooplankton, and organic particles. It does this in three dimensions, and allowing continuous variation over the full 72 hour forecast it makes every day.”

One reason for creating LiveOcean was to help shellfish growers decide when to plant oyster seed and conduct other activities during a time of ocean acidification. Oyster growers in particular want to avoid certain cultivation practices when water conditions become deadly to oyster larvae.

The primary driver of ocean acidification is growing amounts of carbon dioxide in the atmosphere, but acidification is also influenced by excess nitrogen, such as from sewage-treatment plants.

Washington Department of Ecology is investigating the latest sewage spill from the West Point plant after a much larger spill in 2017. For details, read the news release from Ecology and check the related links.

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