Restoration project in Thornton Creek featured in Scientific American article

Friday, April 1, 2022

The Knickerbocker Reach, near Northgate
was the site of the restoration.
Photo by Janet Way

By Ken Berkun

Who knew that rivers had livers? Fortunately for north Seattle, Seattle Public Utilities employee Katherine Lynch, knows. The hyporheic zone, sometimes called the river’s liver and sometimes the river’s gut, is mostly unknown but vital to the health of the river.

Steps lead to the bridge at Knickerbocker Reach
Photo by Janet Way
Extending up to dozens of feet deep and tens of feet wide, the hyporheic zone is a bed of life. Crustaceans, worms, insects of all sorts live and breed in this area. 

Destroy the hyporheic zone and you destroy the river, and in our case, the salmon that used to thrive in Thornton Creek.

The most recent issue of Scientific American (April, 2022) has an article about our very own Thornton Creek and the battle to save its hyporheic zone. 

Brave and persistent, Lynch fights bureaucracy, declining budgets and people like you and me who have no idea what a hyporheic zone even is. 

She starts the battle in 2004 but not until 2014 do the bulldozers roll.

The article is available online for free at

Gies, Erica. “To Revive a River, Restore Its Hidden Gut,” April 2022, Scientific American

Bridge at The Knickerbocker Reach
Photo by Janet Way
This lengthy, but very readable account follows both the battle to rebuild the hyporheic zone, the process of rebuilding it and the sometimes surprising measures of success. 

At Longfellow Creek vandals had released captive Caddisflies, but instead of a ruined experiment, Kate Macneale, an environmental scientist for King County reports:

“Two years later she (Macneale) was sampling fish there and found one of the bugs, a caddisfly, in a fish’s gut. 
"Caddisflies live only for a matter of weeks, so it could not have been an individual from the unintended release: it must have been a “grandkid of that individual,” she says. “I couldn’t believe it.”

As we know from other articles, Thornton Creek still has a way to go, but this very first attempt to rebuild a hyporheic zone is a success in progress:

Warning, spoiler!

Most exciting for Lynch, the hyporheic innovations won the ultimate stamp of approval in the fall of 2018, when Chinook salmon swam in from Puget Sound and spawned in the creek’s restored hyporheic zones.

Thornton Creek flows from Shoreline through NE Seattle to Lake Washington.

Details of the project from the Land Use Information Bulletin


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