San Lorenzo

Experimental Living Levee Could Battle Rising Bay Tides

On a recent Saturday, a few dozen volunteers from the group Save the Bay crouched over a muddy patch of land near the Ora Loma Water Treatment Plant in the East Bay city of San Lorenzo. Before them, a field of hundreds of colored flags which they replaced with small plants that looked like weeds you’d pluck from your garden.

It was all part of an experiment aimed at determining whether a gradual slope of land covered with native grasses, known as a ‘living levee,’ could turn back rising sea levels as well as a typical wall-like levee.

“In contrast to traditional infrastructure that might look like a sea wall or some kind of sea barrier,” said Jason Warner of the Ora Loma Sanitation District, “this is actually is more like a park-like setting.”

The treatment plant teamed up with Save the Bay to build a living levee near the east shoreline where large treatment tanks sat near the edge of the bay. For now, the experimental ground sits inland but could be recreated along the shore if the levee proved effective in combating rising tides.

“There’s a lot of concern about sea rise and what’s going to happen to the houses and businesses along the edge,” Warner said.

Over the last couple months, dozens of volunteers have filled the barren piece of graded soil with plants like dogwood, willows and elderberry as well as native grasses that typically grow around parts of the bay. The group collected clippings of the plants elsewhere and grew them in raised beds on the treatment plant’s grounds. The group expects to plant 70,000 plants on the site.

“With this project we’d be restoring what used to be here in the bay 500 or more years ago,” Warner said.

Warner said in addition to confronting rising sea levels, the plants would also potentially help purify water runoff from the treatment plant flowing back into the bay. The plants would also create habitat for bird and marine life along the shore.

“This is the first project of its kind that’s being done at the edge of the bay like this,” said Donna Ball of Save the Bay. “It’s designed to answer some of the questions of what we should do around sea level rise.”

The scrappy looking seedlings looked more like something you’d throw away after a day of gardening, than a cutting-edge fix for climate change. But Save the Bay’s Jon Backus said the plants will spread out over the next couple years and create a lush landscape.

“Doesn’t look like much now,” Backus said. “But it will look pretty nice once it’s all grown up.”

Warner said researchers from Berkeley will study the levee over the next few years -- running tests with freshwater to see if it's effective. If the "Living Levee," also known as a "Horizontal Levee" works, it could be used in other parts of the bay and beyond.

“There’s a vision for the broader bay,” Warner said, “and application throughout the entire world.”

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