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Seattle treatment plant dumping millions of gallons of wastewater into Puget Sound

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The West Point Treatment Plant near Discovery Park in Seattle. (Photo:

SEATTLE — An equipment shutdown coupled with high tides and heavy rainfall have caused a Seattle treatment plant to dump millions of gallons of untreated wastewater into the Puget Sound.

King County’s West Point Treatment Plant experienced an equipment shutdown early Thursday, the King County Department of Natural Resources and Parks said. The shutdown, along with very high tides and stormwater, nearly flooded the plant.

The plant went into emergency bypass mode to help relieve excess water.

Data pix.

Untreated wastewater is currently being discharged about three-quarters of a mile offshore and 240-feet deep in the Puget Sound in order to "protect the treatment plant from significant flooding," officials said.

Four-hundred millions of gallons of wastewater is dumping untreated into the Puget Sound every 24 hours, officials said. Of that, 10 percent is sewage and 90 percent is stormwater.

There is no estimate for how long the wastewater dump will last, officials said.

King County officials notified health and regulatory agencies about the dump, and will sample water quality and post signs warning people to avoid contact with the water over the next several days.

This is the first time in 10 years the plant has shut down.

This story will be updated as more information becomes available.

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