Forecast: cloudy with a touch of sediment

Forecast: cloudy with a touch of sediment


Why is the water in the Seattle Aquarium’s exhibits sometimes a bit cloudy? Because it’s pumped directly from Puget Sound, where the underwater weather report has recently included (in addition to 100% humidity) colder temperatures and partially cloudy waters. With continued winter rain events on the horizon, we can expect to see less-than-crystal-clear water in our exhibits many more times this year.

This begs the question: what causes the water in the Sound to get cloudy? Seasonal rains and wind stir up sediment from the bottom of local rivers; the sediment is then carried down to Puget Sound, where it causes reduced visibility. This is a natural cycle that provides nutrients (like carbon and nitrogen) to Puget Sound. Read on for answers to some common questions we’ve received about our cloudy water.

Does the Aquarium have a filtration system?

The pumps off Pier 59 bring in over 4,000 gallons of saltwater from Elliott Bay every single minute. That water goes through various sand filters, UV filters and coolers depending on the destination. Despite all that, the water in our exhibits still provides a very good indication of what water conditions are like out in Puget Sound. When it’s cloudy in the Sound—it’s cloudy in our exhibits.

How does this affect animals in the Sound?

These seasonal rains are helpful to adult salmon! When salmon are born, they imprint on the scent of their home stream, since each river and stream has a distinct chemical “fingerprint.” These seasonal rains wash the scent of the river downstream, helping to lead adult salmon home.

Is it pollution?

Though the cloudiness is not pollution, it is a good reminder that all the rain from our streets and neighborhoods washes down to the Sound, either directly or through storm drains. No matter where you live, all drains lead to the ocean.

Here are a few ways you can help keep the Sound clean:

Remember that untreated water from storm drains goes directly into Puget Sound, right into the homes of our underwater neighbors. We can carefully dispose of chemicals and fertilizers and pick up after our pets to keep Puget Sound clean. Also, keep your car tuned up to ensure that leaking oil and chemicals don’t get washed into the Sound—and wash it at environmentally friendly carwashes.

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