Building with nature: Can reviving a marsh save this California town from sea level rise?
California’s Bay Area is built on bayous. Some are as deep as 100 feet, and others rise just as high. Most are too dry to be used for anything else. So they fall into disuse. One such is Redwood City, built on a marsh in the hills above the San Francisco Bay.
A map of the San Francisco Bay Area. Courtesy of Google Maps.
“We’re really worried about the rising sea,” says Robert Hildebrand, the mayor of Redwood City. “In our history, we’ve been here since the 1880s. We don’t know if we can survive, especially if sea level rises again.”
One of Hildebrand’s first priorities was to build a seawall to keep water out of the marshlands that have surrounded the city for more than 100 years. But after extensive testing, he knew it wouldn’t work. And it wouldn’t work forever. He’d only been elected in 2016 — and his administration had taken a big hit. Half the city’s budget had to be cut to $2 million to help the city deal with sea-level rise, the result of climate change. Half that was already in the budget, and all the water infrastructure on the bay had been taken out of the city budget.
The city then began a search for a less costly water source. It became apparent that restoring a marsh would be the solution.
Redwood City’s land has been flooded with saltwater and sediment over the years, making it unusable for agriculture. But once the city began looking for a solution to its water problem, it found one — a marsh on the city’s northern end that is so salty that it’s dry. “That was kind of a game changer,” says Elizabeth Loomis, a professor of geosciences at Stanford University who has studied the marsh in Redwood City.
Redwood City started looking at possible solutions to its water problem in earnest in 2017, when it received a grant from the California
