If you ask people to name some of the rivers that flow into Puget Sound, they might list the Skagit or the Nisqually or any one of thousands of creeks and streams that arrive from the surrounding mountains. They are less likely to mention that Puget Sound’s largest river is one you can’t see from the land.
It’s a river that has no name but starts deep off the Washington coast and pushes trillions of gallons of ocean water through the Strait of Juan de Fuca in a raging torrent the size of the Amazon. This underwater Amazon flows through Juan de Fuca Canyon stirring up turbulent waves and eddies that churn the waters of Puget Sound deep below the surface.
“Yeah, it’s pretty close to the size of the Amazon except that it’s flowing in, toward the land, and then getting mixed and flowing out again,” University of Washington oceanographer Parker MacCready told us recently. This oceanic river, MacCready said, is a big reason Puget Sound is Puget Sound. For one thing, it’s part of why the water is salty — imagine a giant spigot that fills the basin with ocean water — but there’s more to the story.
The interaction between fresh and salt water stokes an engine that drives water circulation throughout the entire basin, something intensely important to the understanding and management of Puget Sound.
This giant current is part of Puget Sound’s estuarine exchange flow, a phenomenon little-known outside of scientific circles that means everything to Puget Sound’s vitality and health. This flow brings in life-giving nutrients from the ocean that feed Puget Sound’s creatures, from salmon to orcas. It also drives water circulation throughout the entire basin, something intensely important to the understanding and management of Puget Sound. It can help explain the impacts of wastewater, the movement of toxic chemicals, where our fish and orcas roam, and even whether there is enough oxygen in the water to sustain life.