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Seattle's Green Lake Going From Murky To Clear And Blue

Daisies cover a patch of grassy shoreline on the west side of Seattle's Green Lake Park this spring. The weekend forecast calls for sunny skies and temperatures in the 70s.
Gary Davis
/
KPLU
Green Lake has suffered from toxic algae blooms during warmer months. This week's treatment with aluminum sulfate will reduce phosphorus in the water, which is a nutrient that feeds the algae.

 

Seattle’s Green Lake is known for having water resembling pea soup. But by the end of this week, the color of the lake will we be transformed to a color that’s almost tropical.

The instigator of this change isa chemical called aluminum sulfate which is being spread across the 259 acre lake this week from a barge.The chemical will bind with phosphorus, which feeds the toxic algae than can bloom in the lake during warmer weather.

 

Aluminum sulfate is a food-grade chemical that is used for many things, including making pickles.

When the lake was treated this way in the past, one man concerned about the chemicals’ effects,

“was swimming behind the barge attempting to get sick from the chemical application. And he swam until he was almost hypothermic. And then he got out of the lake. They asked him if he was sick and he said, ‘No, I’m just really cold,” said Chris Mueller with the Seattle Parks and Recreation.

 

The last time Green Lake was hit by a toxic algae bloom was in 2014. The algae contains a liver toxin that can be especially dangerous to animals and small children.

 

This week’s treatment is expected to last about 10 years and is costing the city $1.5 million dollars.The parks department says when it’s done, Green Lake will be noticeably more clear and blue.

 

Jennifer Wing is a former KNKX reporter and producer who worked on the show Sound Effect and Transmission podcast.